Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows.

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.

Effects of dietary deoiled soy lecithin supplementation on milk production and fatty acid digestibility in Holstein dairy cows.

Deoiled soy lecithin is a feed additive enriched in phospholipids. Our study evaluated the effects of dietary deoiled soy lecithin supplementation on (1) milk production and composition, (2) plasma and milk fatty acid (FA) content and yield, and (3) apparent FA digestibility and absorption in lactating dairy cows fed fractionated palm fat. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 days in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate (MPA) or high palmitic acid (HPA) content at 1.75% of ration dry matter (72 or 99% palmitic acid, respectively; n = 8/palm fat diet). On each palm fat diet, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design. Following a 14-d covariate period, lecithin supplementation spanned 14 d, with milk and blood collected during the final 3 d. Milk composition and pooled plasma markers were measured. The statistical model included the fixed effects of palm fat type, lecithin dose, period, and the interaction between palm fat type and lecithin dose. The random effect of cow nested within palm fat group was also included. Lecithin linearly decreased dry matter intake. In cows fed HPA, lecithin feeding reduced milk fat content and tended to decrease milk fat yield. Although no changes in milk yield were observed, a quadratic reduction in 3.5% fat-corrected milk was observed with increasing lecithin dose. Lecithin linearly increased energy-corrected milk efficiency in cows fed MPA. Lecithin supplementation also decreased milk urea nitrogen, relative to unsupplemented cows. The proportion of 16-carbon FA in milk fat decreased linearly with lecithin dose, whereas 18-carbon FA increased linearly. Lecithin reduced de novo FA (<16-carbon) content and tended to increase preformed FA (>16-carbon) content in a linear manner. Compared with MPA, HPA diets reduced apparent total and 16-carbon FA digestibility and absorption. Deoiled soy lecithin feeding did not modify FA digestibility or absorption. Our observations suggest that soy lecithin feeding modifies rumen digestion to reduce dry matter intake and change milk composition.

Methyl donor supplementation suppresses the progression of liver lipid accumulation while modifying the plasma triacylglycerol lipidome in periparturient Holstein dairy cows.

Co-supplementation of methyl donors may lower hepatic lipid content in transition cows. To define the ability of methyl donor supplementation (MDS) to reduce hepatic lipid content and modify the plasma lipidome, 30 multiparous Holstein cows (2.04 ± 0.69 lactations; 689 ± 58 kg of body weight; 3.48 ± 0.10 units of body condition score) were fed a ration with or without rumen-protected methyl donors (22 g/d of Met, 10 g/d of choline chloride, 3 g/d of betaine, 96 mg/d of riboflavin, and 1.4 mg/d of vitamin B12) from d -28 before expected calving through d 14 postpartum. Cows were randomly enrolled based on predefined selection criteria (body condition score and parity). Base diets without MDS were formulated for gestation (15.4% crude protein with a predicted Lys-to-Met ratio of 3.25; 1.44 Mcal of net energy for lactation/kg of dry matter) and lactation (16.6% crude protein with a predicted Lys-to-Met ratio of 3.36; 1.64 Mcal of net energy for lactation/kg of dry matter). Blood sampling occurred from d -28 relative to expected calving through d 14 postpartum. Liver tissue was biopsied at d -28 relative to expected calving and on d 5 and 14 postpartum. In addition to routine analyses, serum AA concentrations on d 10 and 12 were quantified using mass spectrometry. Plasma triacylglycerol (TAG) and cholesteryl esters (CE) were qualitatively measured using time-of-flight mass spectrometry. Data were analyzed using a mixed model with repeated measures. Dry matter intake and milk yield were not modified by MDS. The transition from d -28 relative to expected parturition to d 14 postpartum was characterized by increased plasma fatty acid (0.15 to 0.71 mmol/L) and ß-hydroxybutyrate (0.34 to 0.43 mmol/L) levels and liver lipid content (3.91 to 9.16%). Methyl donor supplementation increased the serum Met level by 26% and decreased the serum Lys-to-Met ratio by 21% on d 10 and 12, respectively. Moreover, the increase in hepatic lipid content from d 5 through 14 postpartum was suppressed with MDS relative to control (3.57 vs. -0.29%). Dietary MDS modified the TAG and CE lipidome. For example, MDS increased plasma TAG 46:3 (carbon number:double bond) by 116% relative to control cows on d 5 postpartum. Moreover, MDS tended to increase plasma CE 34:6. In contrast, MDS lowered plasma TAG 54:8 by 39% relative to control cows on d 5 postpartum. We concluded that in the absence of gains in dry matter intake and milk and milk protein yields, dietary MDS slows the progression of hepatic lipid accumulation and modifies the plasma TAG lipidome in transition cows.

Circulating low-density lipoprotein ceramide concentrations increase in Holstein dairy cows transitioning from gestation to lactation.

Low-density lipoprotein (LDL) ceramide causes insulin resistance in obese diabetic nonruminants. Because previous work suggests that liver-derived ceramide may impair insulin action in postpartum cows, our objectives were to characterize peripartal changes in lipoprotein ceramides. We further studied the effects of prepartum adiposity on lipoprotein ceramide levels. Twenty-eight pregnant Holstein cows (parity = 3.65 ± 1.62) with lean (body condition score, BCS = 2.97 ± 0.16; body weight, BW = 630 ± 55.2 kg; n = 15) or overweight (BCS = 3.93 ± 0.27; BW = 766 ± 46.1 kg; n = 13) body condition 28 d before expected parturition were evaluated. Sampling occurred on d -20.5 ± 1.74, -13.8 ± 1.71, -7.84 ± 4.07, -6.71 ± 1.00, -3.92 ± 0.64, and -1.28 ± 0.61 (before parturition); daily until d 8 postpartum; and on d 10, 12, 14, 21, and 28. Adipose tissue and liver were biopsied on d -7.84 ± 4.07 and 10. Postpartum insulin sensitivity was assessed using the hyperinsulinemic-euglycemic clamp. Lipoprotein fractions were isolated using liquid chromatography. Sphingolipids were quantified using mass spectrometry. Data were analyzed using a mixed model with repeated measures. Overweight cows had a higher BCS and BW at enrollment relative to lean cows, but BCS and BW were similar postpartum. Overweight cows lost more body condition (0.97 ± 0.36 vs. 0.55 ± 0.16 BCS units) and BW (291 ± 67.3 vs. 202 ± 54.5 kg) during transition relative to lean cows. Adipocyte volume and counts declined from prepartum to postpartum (50.4 and 13.7%, respectively), and adipocyte volume was greater (48.2%) in overweight cows prepartum relative to lean cows. Although DMI was comparable between BCS groups, milk yield tended to be greater in overweight cows. Plasma free fatty acid and ß-hydroxybutyrate and liver lipid levels were 40, 16, and 37% greater, respectively, in overweight cows compared with lean cows. Glucose infusion rate during the hyperinsulinemic-euglycemic clamp tended to be lower in overweight cows. Ceramide levels within triacylglycerol-rich lipoprotein fractions declined postpartum, whereas LDL ceramide increased postpartum. Overweight cows had lower triacylglycerol-rich lipoprotein C16:0-ceramide levels relative to lean cows. Prepartum LDL C24:0-ceramide levels were greater in overweight cows relative to lean cows. Independent of prepartum adiposity, we concluded that serum LDL ceramide levels are elevated in early-lactation cows experiencing adipose tissue free fatty acid mobilization and hepatic steatosis.

Effects of abomasal infusions of fatty acids and one-carbon donors on hepatic ceramide and phosphatidylcholine in lactating Holstein dairy cows.

Our objectives were to (1) determine whether the abomasal infusion of behenic acid (C22:0) elevated hepatic ceramide relative to palmitic acid (C16:0) or docosahexaenoic acid (C22:6n-3) infusion; (2) assess whether the abomasal infusion of choline chloride or l-serine elevated hepatic phosphatidylcholine (PC) in cows abomasally infused with C16:0; and (3) characterize the PC lipidome in cows abomasally infused with C22:6n-3, relative to C16:0 or C22:0 infusion. In a 5 × 5 Latin square design, 5 rumen-cannulated Holstein cows (214 ± 4.9 DIM; 3.2 ± 1.1 parity) were enrolled in a study with 6-d periods. Abomasal infusates consisted of (1) palmitic acid (PA; 98% C16:0); (2) PA + choline chloride (PA+C; 50 g/d choline chloride); (3) PA + l-serine (PA+S; 170 g/d l-serine); (4) behenic acid (BA; 92% C22:0); and (5) an algal oil rich in docosahexaenoic acid (DHA; 44% C22:6n-3). Emulsion infusates provided 301 g/d of total fatty acids containing a minimum of 40 g/d of C16:0. Cows were fed a corn silage-based diet. Milk was collected on d -2, -1, 5, and 6. Blood was collected and liver biopsied on d 6 of each period. Although we did not detect differences in milk yield, milk fat yield and content were lower in cows infused with DHA relative to PA. Plasma triacylglycerol concentrations were lower with DHA treatment relative to PA or BA. Cows infused with DHA had lower plasma insulin concentrations relative to cows infused with PA only. For objective 1, hepatic ceramide-d18:2/22:0 was highest in cows infused with BA relative to other treatments. For objective 2, plasma free choline concentrations were greater in PA+C cows relative to PA; however, we did not observe this effect with PA+S. Plasma total PC concentrations were similar for all treatments. Regarding the hepatic lipidome, a total of 18 hepatic PC were higher (e.g., PC-16:1/18:2) and 25 PC were lower (e.g., PC-16:0/22:6) with PA+C infusion relative to PA. In addition, 17 PC were higher (e.g., PC-20:3/22:5) and 21 PC were lower (e.g., PC-18:0/22:6) with PA+S infusion relative to PA. For objective 3, hepatic concentrations of many individual saturated PC (e.g., PC-18:0/15:0) were lower with DHA relative to other treatments. Hepatic concentrations of highly unsaturated PC with very-long-chain fatty acids (e.g., PC-14:0/22:6) were higher in DHA-infused cows relative to PA, PA+C, PA+S, or BA. The abomasal infusion of emulsions containing palmitic acid, palmitic acid with choline chloride or serine, behenic acid, or docosahexaenoic acid influence the hepatic ceramide and PC profiles of lactating cows.

Hot topic: Ceramide inhibits insulin sensitivity in primary bovine adipocytes.

In nonruminants, the sphingolipid ceramide inhibits insulin sensitivity by inactivating protein kinase B (AKT) within the insulin-signaling pathway. We have established that ceramide accrual develops with impaired systemic insulin action in ruminants during the transition from gestation to lactation, dietary palmitic acid supplementation, or controlled nutrient restriction. We hypothesized that ceramide promotes AKT inactivation and antagonizes insulin sensitivity in primary bovine adipocytes. Stromal-vascular cells were grown from bovine adipose tissue explants and cultured in differentiation media. To modify ceramide supply, we treated differentiated adipocytes with (1) myriocin, an inhibitor of de novo ceramide synthesis, or (2) cell-permeable C2:0-ceramide. Insulin-stimulated AKT activation (i.e., phosphorylation) and 2-deoxy-D-[3H]-glucose (2DOG) uptake were measured. Treatment of adipocytes with myriocin consistently decreased concentrations of ceramide, monohexosylceramide, and lactosylceramide. The insulin-stimulated ratio of phosphorylated AKT to total AKT was increased with myriocin but decreased with C2:0-ceramide. Moreover, adipocyte insulin-stimulated 2DOG uptake was decreased with C2:0-ceramide and increased with myriocin. We conclude that ceramide inhibits insulin-stimulated glucose uptake by downregulating AKT activation in primary bovine adipocytes.

Spin Resonance Clock Transition of the Endohedral Fullerene

The endohedral fullerene ^{15}N@C_{60} has narrow electron paramagnetic resonance lines which have been proposed as the basis for a condensed-matter portable atomic clock. We measure the low-frequency spectrum of this molecule, identifying and characterizing a clock transition at which the frequency becomes insensitive to magnetic field. We infer a linewidth at the clock field of 100 kHz. Using experimental data, we are able to place a bound on the clock's projected frequency stability. We discuss ways to improve the frequency stability to be competitive with existing miniature clocks.

Subtype associations with HIV-associated neurocognitive disorder in China.

Factors associated with HIV-associated neurocognitive disorders (HAND) include CD4(+) nadir and count, HIV RNA level, and HIV-1 subtype. Here, we investigated demographical and clinical markers with respect to HAND in a homogenous Chinese population. Individuals with HAND (global deficit score ≥0.5) had lower nadir (p < 0.01) and CD4(+) counts (p = 0.03). HAND was also associated with AIDS (p < 0.01), but subtype was not (p = 0.198). Furthermore, worse impairment correlated with higher viral diversity (r = 0.16, p < 0.01), lower nadir (r = -0.17, p < 0.01), and CD4(+) counts (r = -0.11, p = 0.01). These remained significant even when correcting for subtype. Our findings suggest that subtype does not have a major impact on HAND.

Somatotropin increases plasma ceramide in relation to enhanced milk yield in cows.

Recombinant bovine somatotropin (rBST) changes metabolism to spare glucose for milk synthesis in cows. Ceramides inhibit insulin responsiveness in bovine adipocytes and are associated with insulin resistance and milk production in cows. The mechanisms by which rBST supports lactation may involve ceramide. Eight multiparous lactating Holstein cows were enrolled in a 2 × 2 replicated Latin square design with 14-d periods. Cows received a single rBST injection (Posilac; Elanco Animal Health, Indianapolis, IN; 0.062 mg/kg BW) or no injection (CON). An epinephrine challenge, insulin tolerance test, and liver biopsy were performed. Somatotropin enhanced the conversion of feed nutrients into milk components and increased plasma free fatty acid (FFA) concentrations (P < 0.01). Area-under-the-curves for FFA in response to epinephrine and insulin were greater in rBST-treated cows. In response to insulin, glucose concentrations (20- and 30-min post-challenge) and insulin area-under-the-curve were higher with rBST treatment (P < 0.05, <0.10, and <0.01), suggesting insulin resistance. Somatotropin modified the plasma lipidome. For example, rBST decreased plasma di- and triacylglycerol levels (eg, DG-50:1 and TG-18:0/16:0/16:1), phosphatidylcholines and sphingomyelins (P < 0.05). Somatotropin increased plasma total and very-long-chain (C22:0-, C24:0-, C26:0-) ceramide concentrations (P < 0.01). Liver ceramide concentrations were not modified. Plasma ceramides were positively correlated with circulating FFA (r ~ 0.57; P < 0.05) and milk yield (r ~ 0.63; P < 0.05). We conclude that rBST administration modifies the bovine lipidome and increases plasma ceramide concentrations in association with increased milk production in cows.

The placebo as performance: speaking across domains of healing.

In this article I explore the placebo and the placebo effect from a performance-studies perspective. I use this examination to argue for the placebo as a possible dialogic starting point between performance studies and qualitative health scholars. Using Lock and Scheper-Hughes' concept of three bodies (the individual body, the social body, and the body politic), I explain how the placebo as performance opens dialogue by speaking across these three bodies. I argue that the placebo as performance offers a yet-unexplored and heuristic way to bridge the unfortunate divide that often exists between qualitative and quantitative ways of understanding healing. By exploring these connections and offering a history of blind testing in the medical community, I explain how the placebo requires multiple lenses to be understood in the healing process, and by extension opens up traffic between different ways of knowing.

Altered response to pneumococcal polysaccharide in offspring of immunologically paralyzed mice.

The dose of pneumococcal polysaccharide type III required to induce immunologic paralysis in newborn offspring of immunologically paralyzed mice was one-tenth of the corresponding paralyzing dose for newborn offspring of normal mice. Similarly, immunization of the offsprinig of the paralyzed mice was accomplished with one-tenth the dose of polysaccharide necessary to immunize normal newborn mice. The altered susceptibility of newborn mice from paralyzed mothers to the induction of both paralysis and immunity was predicted from theories of antibody formation which postulate that the induction of tolerance or immunity is controlled by the concentration of natural antibodies specific for the antigen used.

Helium-neon laser: thermal high-resolution recording.

Scan-line recording by means of a moving laser spot has been achieved on metallic and organic thin films Recording rates of the order of one million spots per second were obtained with a laser beam power of 38 milliwatts at the recording surface. Typical recorded line widths were of the order of 2 microns.

In vivo and in vitro activation of natural killer cells in advanced cancer patients undergoing combined recombinant interleukin-2 and LAK cell therapy.

Patients with advanced metastatic cancer were given combined autologous lymphokine activated killer (LAK) cell and recombinant interleukin-2 (rIL-2) therapy on a National Cancer Institute extramural phase II trial. Systemic administration of rIL-2 resulted in pronounced lymphocytopenia. Within two days after completion of in vivo rIL-2 therapy, there was a dramatic increase in absolute numbers of circulating lymphocytes, and cytotoxic activity against tumor cell targets was mediated by peripheral blood lymphocytes, indicating in vivo generation of LAK activity. Patients were leukapheresed and cells cultured for three to four days in rIL-2. rIL-2 cultured cells from all patients demonstrated cytotoxic activity. In order to characterize the effector cell, T cells and natural killer (NK) cells were isolated to greater than 95% purity by flow cytometry. Cytotoxic activity was mediated by rIL-2--activated NK cells, whereas T cells demonstrated no substantial activity. The circulating in vivo cytotoxic effectors detected after in vivo rIL-2 therapy were also shown to be rIL-2--activated NK cells. Results from these studies demonstrate that all patients were capable of generating a cytotoxic response, and that the cytotoxic effector cells were rIL-2--activated NK cells, identified by the phenotype CD3--, Leu 19+.

CASS Registry long term surgical survival. Coronary Artery Surgery Study.

OBJECTIVES: To show the effect of clinical, angio and demographic traits on late survival of Coronary Artery Surgery Study (CASS) patients following coronary artery bypass grafting (CABG) and introduce Hazard Function analysis to CASS survival data. METHODS: Patients were reached by mail survey with 94% response. By National Death Index, vital status was obtained in 99.7% (n = 8221) with a mean follow up of 15 years. Cox proportional hazard and Blackstone Hazard Function regressions were used to assess effects of preoperative traits. RESULTS: Ninety percent of patients were alive at 5, 74% at 10 and 56% at 15 years. Of those age 65 and age 75 at operation, 74% and 59% were living at 10 years and 54% and 33% at 15 years (now age 90), survival exceeding the matched U.S. population. Hazard Function falls rapidly after CABG to 9 to 12 months, then rises, doubling by 15 years. Young patients, below age 35, had lower late survival. The time-segmented Cox model (divided at time suggested by the Hazard Function) identified traits showing predictive power early, throughout and late. Female sex, small body surface, ischemic symptoms and emergency status affected survival early. Heavier weight, infarct(s), diuretics, diabetes, smoking, left main and LAD stenosis and use of vein grafts only increased hazard late only. CONCLUSIONS: There are still lessons from the CASS database. CABG in the elderly is supported by the survival pattern of our patients age 75 at operation. Time-segmented Cox analysis and Hazard Function analysis separate baseline variables into those that predict early mortality and those that predict long survival.

Effects of smoking on survival and morbidity in patients randomized to medical or surgical therapy in the Coronary Artery Surgery Study (CASS): 10-year follow-up. CASS Investigators.

OBJECTIVES: The goal of this study was to ascertain how continued cigarette smoking or smoking cessation related to long-term survival and morbidity in patients with established coronary artery disease managed with medical therapy or coronary bypass surgery. BACKGROUND: Although the association of cigarette smoking with coronary artery disease is well established, the morbidity and mortality associated with smoking behavior in patients with such disease receiving medical or surgical therapy are less well established. METHODS: The 780 patients randomized to medical therapy or coronary bypass surgery in the Coronary Artery Surgery Study (CASS) were subgrouped according to smoking behavior during a mean 11.2-year follow-up interval. Comparisons between smokers and nonsmokers were accomplished by univariate and Cox time-dependent multivariate analyses. RESULTS: Survival at 10 years after entry into the study was 82% among 468 patients who reported no smoking during follow-up (nonsmokers) compared with 77% among the 312 smokers (p = 0.025). Survival was 80% among those who smoked at entry but stopped (quitters) versus 69% among those who continued smoking (p = 0.025). For patients who smoked at baseline and were randomized to bypass surgery, survival at 10 years was 84% among quitters and 68% among nonquitters (p = 0.018); the difference in survival between quitters (75%) and nonquitters (71%) was less among those randomized to medical therapy (p = NS). Among those who smoked at baseline, continued smoking increased the relative risk of death by 1.73. After 10 years, smokers, in comparison with nonsmokers, were less likely to be angina free and more likely to be unemployed and had more activity limitation and more hospital admissions (primarily for chest pain, heart attack, cardiac catheterization, peripheral vascular surgery and stroke). CONCLUSIONS: Thus, among patients with documented coronary artery disease, continued cigarette smoking may result in decreased survival--especially among those undergoing bypass surgery. Moreover, smokers have more angina, more unemployment, a greater limitation of physical activity and more hospital admissions.

Clinical resistance to vasopressin. Detection of antibody by hemagglutination.

We describe a patient with hypothalamic diabetes insipidus who after 20 years became refractory to the effect of commercial vasopressin injection. Vasopressin antibodies were measured using a sensitive hemagglutination technique. Resistance was associated with a high titer of antibodies that disappeared once vasopressin therapy was withdrawn and the diabetes insipidus was controlled with chlorpropamide. Antibodies were also measured in four additional patients with diabetes insipidus while they were or were not receiving vasopressin. A patient who had received the drug for only two years already had a substantial titer of antibodies to vasopressin, but in this case the response to the hormone was not impaired.

The limited utility of fibrinogen I 125 leg scanning.

Using venography as the reference procedure, this study examined the utility of fibrinogen I 125 scanning for the detection or demonstration of deep venous thrombosis. The results demonstrate the inability of leg scanning to detect accurately the presence or absence of thrombi in the deep venous system. Most striking was the lack of sensitivity of this procedure in areas where the propensity for embolization is greatest. Sensitivity is extremely low in the anatomic areas where leg scanning demonstrates reasonable specificity. The results are nearly identical in the extremity not operated upon. The validity of all prior studies relying heavily or exclusively on 125I leg scans to determine the presence or absence of thrombi must be critically reassessed.

Evaluation of changes in trabecular bone architecture and mechanical properties of minipig vertebrae by three-dimensional magnetic resonance microimaging and finite element modeling.

The study objective was to analyze the three-dimensional (3D) trabecular architecture and mechanical properties in vertebral specimens of young and mature Sinclair minipigs to assess the relative contribution of architecture to bone strength. We used 3D magnetic resonance microimaging (MRmicroI) and direct image analysis to evaluate a set of standard structural measurements and new architectural descriptors of trabecular bone in biopsy specimens from L2, L3, and L4 vertebrae (n = 16 in each group) from young (mean age, 1.2 years) and mature (mean age, 4.8 years) minipigs. The measurements included bone volume/tissue volume (BV/TV), marrow star volume (Ma.St.V), connectivity density (ConnD), and two new parameters, percent platelike trabeculae (% plate) and percent bone in the load direction (% boneLD). The % plate, calculated from surface curvature, allowed the delineation of plates from rods. The % boneLD quantified the percentage of bone oriented along the long axis of the vertebral body. We showed that 3D MRmicroI can detect the subtle changes in trabecular architecture between the two age groups. ConnD, star volume, % plate, % boneLD, and BV/TV were found to be more effective than the model-based, derived indices (trabecular thickness [Tb.Th], trabecular separation [Tb.Sp], and trabecular number [Tb.N]) in differentiating the structural changes. BV/TV, % plate, and % boneLD significantly increased (p < 0.05) in all three vertebral sites of the mature minipigs. The significant decrease in ConnD and star volume in the mature vertebra was consistent with the concurrent increase of platelike trabecular bone (p < 0.05). Overall, ConnD, star volume, % plate, and % boneLD provided a coherent picture of the architectural changes between the two age groups. Apparent modulus and maximum stress were determined experimentally on biopsy specimens from L2 vertebrae (n = 16). When apparent modulus was predicted using 3D MRmicroI data sets as input for finite element modeling (FEM), the results were similar to the experimentally determined apparent modulus (p = 0.12). Both methods were then used to compare the young and the mature animals; the experimental and predicted apparent modulus were significantly higher for the mature group (p = 0.003 and 0.012, respectively). The experimental maximum stress in the vertebra of the mature animals was twice as high as that for the young animals (p = 0.006). Bone quantity (BV/TV or bone mineral content [BMC]) alone could explain approximately 74-85% of the total variability in stress and modulus. The inclusion of either ConnD or % boneLD with BV/TV in a multiple regression analysis significantly improved the predictability of maximum stress, indicating that architecture makes additional contributions to compressive strength in normal minipig vertebra.

Cerebellar stimulation: effects on septal region, hippocampus, and amygdala of cats and rats.

The influence of the cerebellum on activity of the septal region, hippocampus, and amygdala of cats and rats was determined by obtaining unit recordings from those supratentorial sites with cerebellar stimulation. With stimulation of the postral vermis, fastigial nucleus, and intervening midline folia of the cerebellum, units in the septal region were facilitated, whereas those in the hippocampus were inhibited. Mixed results were obtained in the amygdala, some units being facilitated and others inhibited. Stimulation over the lateral cerebellar hemispheres and dentate nucleus, on the other hand, yielded no changes in activity, and stimulation of the posterior vermis produced inconsistent septal facilitation and no hippocampal response. With stimulation of the rostral cerebellar vermis and fastigial nucleus, evoked potentials at the supratentorial sites were of very short delay times, indicating direct pathways from the cerebellum to the septal region, hippocampus, and amygdala. When the dentate and fastigial nuclei were lesioned in cats, the firing rate of cells at supratentorial sites was not affected and cerebellar vermis stimulation did not significantly alter delay times of evoked responses, providing further evidence of a direct influence of the cerebellar vermis on the supratentorial sites. Relating these findings to previous patient and animal data provides a rationale for use of specific types of cerebellar simulation in the treatment of intractable behavioral disorders and epilepsy.

Role of NMDA receptors in adult primate cortical somatosensory plasticity.

We have previously shown that most of the reorganization that typically follows median nerve transection in adult squirrel monkeys is dependent on normally functioning N-methyl-D-aspartate (NMDA) receptors. Here, we have evaluated two additional hypotheses: (1) is the immediate "unmasking" found after median nerve transection NMDA receptor-dependent? and (2) are NMDA receptors necessary for both the initiation and maintenance of the second phase of reorganizational changes, or only the former? To address these issues, we implanted osmotic minipumps subcutaneously to deliver an NMDA receptor antagonist (3-((+/-)-2- carboxypiperazin-4-yl)propyl-1-phosphonic acid, CPP) systemically either before examining the immediate effects of median nerve transection, or after reorganization had presumably occurred. For the first set of experiments, NMDA receptor blockade was initiated either 1 or 4 weeks prior to multi-unit mapping in area 3b followed by transection of the median nerve and remapping of the cortex. In the second set of experiments, median nerve transection was followed 4 weeks later by either 1 or 4 weeks of NMDA receptor blockade prior to terminal mapping. We report that the immediate unmasking of new receptive fields after acute nerve injury is not prevented by NMDA receptor blockade; nor are completely reorganized cortical maps dependent upon NMDA receptors for their maintenance. We conclude that the immediate changes in cortical topography are not due to an NMDA receptor-dependent mechanism, but more likely due to release from tonic inhibition. Furthermore, the later phase of reorganization, as for some forms of hippocampal long-term potentiation (LTP), is dependent on normally functioning NMDA receptors for its initiation, but not for its maintenance.