A novel mechanism for controlling the activity of alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein. Multiple regulatory sites for 39-kDa receptor-associated protein

The alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein (alpha 2MR/LRP) consists of two polypeptides, 515 and 85 kDa, that are noncovalently associated. A 39-kDa polypeptide, termed the receptor-associated protein (RAP), interacts with the 515-kDa subunit after biosynthesis of these molecules and remains associated on the cell surface. This molecule regulates ligand binding of alpha 2MR/LRP (Herz, J., Goldstein, J. L., Strickland, D. K., Ho, Y. K., and Brown, M. S. (1991) J. Biol. Chem. 266, 21232-21238). Titration and binding studies indicate that RAP binds to two equivalent binding sites on alpha 2MR/LRP, with a KD of 14 nM. Heterologous ligand displacement experiments demonstrated that RAP completely inhibits the binding of 125I-activated alpha 2M to human fibroblasts and to the purified alpha 2MR/LRP, with a Ki of 23 and 26 nM, respectively. A direct correlation between the degree of binding of RAP to the receptor and the degree of ligand inhibition was observed, indicating that as the RAP binding sites are saturated, alpha 2MR/LRP loses its ability to bind ligands. Thus, the amount of RAP bound to alpha 2MR/LRP dictates the level of receptor activity. A model is proposed in which alpha 2MR/LRP contains multiple ligand binding sites, each regulated by a separate RAP site.

Effect of hot-fat trimming on factors associated with the subprimal yield of beef carcasses

Thirty-two crossbred cattle (steers = 17; heifers = 15) exhibiting an ultrasound fat thickness at the 12 to 13th rib region of at least 10 mm were selected from a slaughter shift at a commercial packing plant. After splitting, alternating sides of each carcass were trimmed of 1) subcutaneous fat in excess of 6.4 mm; 2) all kidney, pelvic, and heart fat; and 3) all cod or udder fat and fat in the flank region. Both sides of each carcass were fabricated into subprimals (final trim level of 6.4 mm) according to normal industry procedures. Effect of hot-fat trimming, yield grade (3, 4, and 5), and gender on hot-fat trim, fabrication fat trim, major subprimal, and total subprimal yield of untrimmed and trimmed carcasses were determined. Higher numerical yield grade (YG) corresponded with higher (P less than .05) percentages of hot-fat trim. Hot-fat trimming increased (P less than .05) the difference in fabrication fat trim between steers and heifers and between YG 3 and YG 5. Steers and heifers differed (P less than .05) in percentage of major subprimals and total subprimals when processed conventionally, whereas hot-fat trimming eliminated this difference (P less than .05). Untrimmed YG 3 carcasses had 3.1 and 5.0% higher major subprimal yield (P less than .05) than untrimmed YG 4 and YG 5 carcasses, respectively, whereas hot-fat trimming reduced this difference to 2.5% for YG 4 and to 3.7% for YG 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of real-time ultrasound and other live measures to carcass measures as predictors of beef cow energy stores

Thirty-nine mature cows were divided into three condition groups on the basis of their subcutaneous fat thickness as determined by real-time ultrasound. A representative animal from each group was measured and slaughtered. The remaining cows with each group were stratified evenly into two groups with one group fed to gain weight and the other to lose weight. Several ultrasound and other live measures were taken every 4 wk and two animals per subgroup were randomly slaughtered. Carcass data were collected and one side of each carcass was boned, ground, mixed, and subsampled for fat and protein determination. Four regression equations were generated to predict percentage of fat (FAT), percentage of protein (PROT), total fat (TOTFAT), total protein (TOTPROT), total calories (CAL), CAL per live weight (CAL/WT), yield grade (YG), and marbling (MARB). The first equation used all live measures (SUB), the second equation used only objective live measures (OBJ), the third equation incorporated traditional live measures (EAS), and the fourth equation used only carcass data (CAR). Adjusted R-squares of the most appropriate equation using the SUB, OBJ, EAS, and CAR measurements were .82, .73, .82, and .82 for FAT; .82, .57, .61, and .66 for PROT; .89, .87, .86, and .85 for TOTFAT; .95, .95, .93, and .74 for TOTPROT; .93, .92, .91, and .90 for CAL; .83, .78, .83, and .82 for CAL/WT; .86, .86, .78, and .93 for YG; and .75, .70, .74, and .74 for MARB, respectively. It seems that condition score or ultrasound with other objective live measures is as accurate in predicting cow composition as carcass measures.

Kinetochore analysis of micronuclei allows insights into the actions of colcemid and mitomycin C

We have induced micronuclei in two strains of diploid human fibroblasts with a known aneugen, colcemid, and a known clastogen, mitomycin C. Using immunofluorescence to detect the presence of kinetochores in micronuclei, we were able to demonstrate a 26.8-fold increase in fluorescence-positive micronuclei (aneuploidy) in colcemid-treated cells. However, colcemid also induced an increase in kinetochore-negative micronuclei. Our findings support previous reports that suggest colcemid may induce chromosome breakage in addition to its major aneugenic effect. The frequency of kinetochore-negative micronuclei (chromosome breakage) in mitomycin C-treated cells rose an average of 7.9-fold in the two test strains, a clear reflection of its clastogenic action. However, a 4-fold increase in the kinetochore-positive fraction was seen. We conclude that the fibroblast micronucleus assay, coupled with kinetochore immunofluorescence, provides a useful screening approach for genotoxic agents. The delineation of the precise mechanism by which an agent perturbs the rates of chromosomal breakage or lag may require more detailed analysis.

An investigation of naming errors following semantic and phonemic cueing

This study investigated the types of verbal errors produced by aphasic patients following phonemic and semantic cueing. Twenty-eight aphasic patients--10 Broca's, 10 Wernicke's and 8 conduction aphasics--served as subjects. Semantic and phonemic cues were administered on object and action confrontation-naming tasks. When subjects did not respond correctly to phonemic cueing, a significantly greater number of phonemic errors were produced, with a concurrent decline in related words and extended circumlocutions. When subjects failed to respond to semantic cueing on the action task, there was an increase in a number of error categories.

Coronary and myocardial adaptations to high altitude in dogs

The objective of this study was to determine whether exposure to high altitude (hypoxic hypoxemia) induces coronary and/or collateral growth. Fourteen mongrel dogs were maintained at a simulated altitude of 18,000 ft for 1 mo and 7 dogs maintained for 3 mo. Within 2 days after their sojourn, the following data were obtained at ambient pressure: pulmonary, right heart chamber, and wedge pressures as well as cardiac output. On an isolated heart preparation, coronary and collateral flows were determined; each vessel was injected with a different color tracer; and the heart was sliced, separated by perfusion territories, and examined for myocardial hypertrophy. We found that pulmonary artery pressures in altitude-adapted animals were higher compared with controls, and coronary flow per gram was increased after 1 mo of exposure but not different from control after 3 mo. Collateral flows were not significantly different from that of control animals, and biventricular hypertrophy occurred with right ventricular dominance. Comparing these results with those that we obtained previously from anemic animals, we favor the hypothesis that oxygen availability rather than blood flow velocity is most likely linked to vascular growth.

Functional anatomical site of intramural collaterals in dogs

The objectives of the present study were to determine quantitatively whether the retrograde flow measurement reflects the total flow from collateral vessels or overestimates or underestimates collateral flow, and to determine the functional anatomical origin of intramural collaterals in the native dog heart. In an isolated heart preparation, three experimental procedures were used. 1) The left circumflex coronary artery was embolized with microspheres of different sizes; then retrograde flows and the peripheral coronary pressures were measured. 2) Epicardial collaterals were cauterized, and retrograde flows were measured before and after cautery. 3) Epicardial collaterals were cauterized followed by embolization of the circumflex coronary artery with different size spheres. We found that 1) the retrograde flow measurement underestimates the total collateral flow to the circumflex coronary artery by approximately 25%, 2) intramural collateral flow constitutes 58 +/- 3.5% of the retrograde flow measurement, 3) the antegrade component of blood flow that is not measured during a retrograde flow measurement is from the intramural collateral circulation, and 4) the functional site of origin of intramural collaterals is greater than 25 microns but less than 80 microns in diameter. We conclude that, in our preparation, retrograde flow underestimates total collateral flow, and that intramural collateral flow is a major component of retrograde flow in the native dog heart.

Effects of percentage Brahman and Angus breeding, age-season of feeding and slaughter end point on feedlot performance and carcass characteristics

Steers (n = 165) of known percentage Brahman (B) and Angus (A) breeding were used to study effects of breed group (A, 3/4A:1/4B, 1/2A:1/2B, 1/4A:3/4B), age-season of feeding (calves fed during the cool season vs yearlings fed during the warm season) and slaughter end point (less than .90, 1.0 to 1.15, 1.27 to 1.40, greater than or equal to 1.5 cm of adjusted fat over the ribeye) on feedlot performance and carcass characteristics. The 1/2B and 3/4B steers had heavier (P less than .05) initial and final feedlot weights than the A and 1/4B steers and higher (P less than .05) unshrunk ADG than the A steers did. Breed types did not differ for feed efficiency. Yearling steers fed in the warm season had higher (P less than .05) unshrunk ADG than calves fed in the cool season, but ADG calculated on an empty-rumen basis did not differ between the two age-seasons of feeding. Calves fed in the cool season were more efficient (P less than .05) than yearlings fed in the warm season when efficiency was expressed on an empty-rumen basis; however, on a live weight basis there was no difference in feed efficiency. No breed group by age-season of feeding interactions on performance were detected. Slaughter end point did not significantly affect feed efficiency on an empty-rumen basis. The 1/2B and 3/4B steers had smaller ribeye areas (REA) per 100 kg hot carcass and lower marbling scores than the 1/4B and A steers. Yearlings fed in the warm season produced heavier carcasses (P less than .05) than calves fed in the cool season. As s.c. fat thickness at slaughter increased, hot carcass weight and numerical yield grade increased, whereas REA per 100 kg of hot carcass decreased. Marbling also increased as fatness increased up to about 1.5 cm subcutaneous fat.

Effects of percentage Brahman and Angus breeding, age-season of feeding and slaughter end point on meat palatability and muscle characteristics

Steers (n = 125) of known percentage Angus (A) and Brahman (B) breeding (A = 31, 3/4A:1/4B = 32, 1/2A:1/2B = 31, 1/4A:3/4B = 31) were slaughtered after being fed as calves during the cool period of the year or fed as yearlings during the warm period of the year. Steers were slaughtered at equivalent outside fat thickness as monitored visually and with real-time ultrasound. Warner-Bratzler shear (WBS) force increased and sensory panel tenderness decreased as percentage Brahman increased. Loin muscle characteristics indicated that differences in tenderness between breed groups were not attributed to cold shortening effects or differences in amount or integrity of connective tissue. Fragmentation values suggested that breed group tenderness differences probably resulted from differences in the muscle fiber component. A 10-d postmortem aging study revealed a differential breed group response to postmortem aging, suggesting that breed groups differed in amount and(or) activity of naturally occurring proteolytic enzymes in muscle tissue.

Coronary sinus pressure has a direct effect on gradient for coronary perfusion

In previous work from this laboratory we demonstrated that the coronary pressure-flow relationship exhibits a zero pressure intercept in the absence of the influence of the collateral circulation. In the present study we determined the effect of varying coronary sinus pressures on coronary perfusion. Specifically, we investigated whether coronary flow would cease when the coronary inflow pressure equaled the coronary sinus pressure. The study was performed while inflow perfusion pressure to all coronary vessels was changed simultaneously in order to reduce the influence of the collateral circulation while coronary sinus outflow was measured. Coronary pressure-flow relationships were obtained for coronary sinus pressures of 0, 10, and 20 mmHg. The results demonstrate a strong correlation between perfusion pressure and coronary sinus pressure (r2 = 0.994 +/- 0.001), which passed through the origin. We conclude that coronary sinus pressures between 0 and 20 mmHg have a direct influence on coronary perfusion.

Microvascular occlusions promote coronary collateral growth

The objective of this study was to examine whether myocardial ischemia without alterations in pressure gradients between large epicardial coronary arteries was a sufficient stimulus to produce coronary collateral growth and development. To accomplish this aim, we partially embolized the circumflex coronary perfusion territory with 25-microns diameter microspheres to produce multiple microvascular occlusions, sufficient to abolish or greatly attenuate coronary vasodilator reserve. The embolization procedure was performed in two groups of dogs during aseptic surgery. After the dogs recovered for 1-3 wk (short-term embolization) or 6-8 wk (long-term embolization), indexes of vascular growth were compared with a group of control animals in which all operative procedures were performed, except embolization. Retrograde blood flow, an index of collateral blood flow and coronary vascular resistance, was determined in an isolated beating empty heart preparation during coronary vasodilation with adenosine. Circumflex retrograde blood flow from the left anterior descending artery was increased from 0.09 ml.min-1.g-1 (sham) to 0.21 and 0.17 ml.min-1.g-1 in the short-term and long-term groups, respectively (P less than 0.05). Collateral blood flow from the septal artery was also increased from 0.03 ml.min-1.g-1 (sham) to 0.08 ml.min-1.g-1 (P less than 0.05) in the short-term group. Collateral contribution from the right coronary artery was not significantly altered in either group of embolization animals. The contributions of epicardial and intramyocardial collaterals to the total retrograde flow were also determined and were found to be different among the three experimental groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Perceptual characteristics of tracheoesophageal voice produced using four prosthetic/occlusion combinations

This study examined and compared perceptual characteristics of tracheoesophageal (TE) voice produced using four different prosthetic/occlusion combinations in 15 tracheoesophageal speakers: 1. using the Blom-Singer duckbill prosthesis and digital occlusion of the tracheostoma; 2. using the Blom-Singer duckbill prosthesis and valve occlusion of the tracheostoma; 3. using the Blom-Singer low-pressure prosthesis and digital occlusion of the tracheostoma; and 4. using the Blom-Singer low-pressure prosthesis and valve occlusion of the tracheostoma. Characteristics of speech produced in each condition were also compared to those of 19 normal speakers. Differences in perceptual ratings made by judges who varied in knowledge about laryngectomees were examined. Results revealed a number of speaking parameters that discriminated among normals and the four TE speaking conditions, and that differed according to the judge's expertise level. Clinical implications are emphasized.

Intramural coronary collateral flow in dogs

The objective of this study was to determine whether intramural collaterals contribute significantly to total retrograde flow (index of collateral flow). The left circumflex, left anterior descending, right, and septal coronary arteries were separately cannulated, and blood flows through these vessels were monitored on an isolated, blood-perfused beating heart preparation. Epicardial collaterals between the borders of the circumflex and right coronary perfusion territories were cauterized, and retrograde flow from the circumflex coronary artery was determined before and after cauterization. This procedure unmasked the intramural collateral flow component to retrograde flow. By occluding and unoccluding the coronary flows from the right, septal, and left anterior descending coronary arteries during these measurements, we were able to determine their contribution to epicardial and intramural collateral flow. We found that, after cauterization, an average of 58 +/- 3.6% of the total retrograde flow remained. The septal and left anterior descending coronary arteries contributed almost equally to this retrograde flow. We concluded that, because the epicardial collaterals were cauterized, the source of retrograde flow was from intramural collaterals and constituted about one-half of the measured retrograde flow in dogs with a native collateral circulation.

Sera-reactivity in inflammatory bowel disease: frequency of recognition of Crohn's disease tissue primed nude mouse lymphoid tissue in an interinstitutional blinded study

We used a double-blinded interinstitutional study with an indirect immunofluorescence assay to evaluate the immunoreactivity of Crohn's disease (CD) sera against hyperplastic and malignant lymph nodes from nude mice primed with CD tissue filtrates. We assessed the reactivity for potential usefulness as a serodiagnostic test by using sera from different clinical subgroups of patients with inflammatory bowel disease. The immunoreactivity of 86 coded sera from ambulatory patients treated at the Mount Sinai Medical Center were examined-29 from patients with CD, 25 from patients with ulcerative colitis (UC), 21 from disease controls, and 11 from normal controls. Each serum was tested at the Albert Einstein College of Medicine against lymph nodes from at least two of six nude mice inoculated with CD tissue filtrates or CD filtrate-induced lymphoma. There was positive immunofluorescent staining in 11 of 29 (38%) CD patients, 4 of 25 (16%) UC patients, 1 of 21 (4.8%) disease controls, and 0 of 11 normal volunteers. Statistically significant differences in immunoreactivity were seen between CD patients compared to non-inflammatory-bowel-disease controls (p = 0.007) and to normals (p = 0.02).

Familial malignant retroperitoneal paraganglioma

Paragangliomas are neuroendocrine tumours and those occurring in the head and neck have well recognized familial association. Retroperitoneal paragangliomas are uncommon and we present two cases of familial malignant retroperitoneal paraganglioma. Review of the literature revealed marked differences in the incidence and malignant potential of familial and non-familial paraganglioma. In contrast to the cases reported here, familial tumours are generally benign, though they may occur at multiple sites. Familial and non-familial paragangliomas may indeed be different disease entities.

Collateral influence on pressure-flow characteristics of coronary circulation

The purpose of this study was to determine the role of the coronary collateral circulation on the shape of the coronary pressure-flow (P-F) relationship and its effects on the pressure at zero flow (PZF) or pressure intercept. We investigated the P-F characteristics of the coronary circulation under two conditions. 1) To minimize the influence of collaterals, we measured coronary flow by timed collections of coronary sinus outflow in 15 dog hearts, as perfusion pressure to all vessels was varied; 2) to maximize the effect of collaterals, we measured circumflex artery flow in six dog hearts, as perfusion pressure to only the circumflex coronary artery was varied and the pressure in the remaining vessels was maintained constant. We used an isolated heart preparation in which ventricular chamber and venous outflow pressures equalled atmospheric pressure and the vessels were maximally dilated with adenosine. In the first condition, the P-F relationship was curvilinear with a PZF of 0 mmHg; in the second condition, the P-F relationship was curvilinear with a PZF of 16 +/- 2 mmHg, and flow was retrograde at pressures below PZF. We conclude that in both conditions the curvilinearity of the coronary P-F relationship was the result of nonlinear elastic properties of blood vessels, not requiring the "waterfall" concept to be invoked, and that in the second condition the influence of collateral vessels produced the positive pressure intercept.

Temporal and perceptual characteristics of tracheoesophageal voice

This study compared the temporal and perceptual characteristics of tracheoesophageal voice produced in four different prosthetic/occlusion conditions: 1. using the Blom-Singer duckbill prosthesis and digital occlusion of the tracheostoma; 2. using the Blom-Singer duckbill prosthesis and valve occlusion of the tracheostoma; 3. using the Blom-Singer low-pressure prosthesis and digital occlusion of the tracheostoma; and 4. using the Blom-Singer low-pressure prosthesis and valve occlusion of the tracheostoma. Characteristics of speech produced in each condition were also compared to those of normal speech. Results revealed significant differences between normal speech and tracheoesophageal speech (in all prosthetic/occlusion conditions) for several temporal and perceptual parameters. In addition, important trends were noted among tracheoesophageal prosthetic/occlusion conditions.

Genotype and the cryopreservation process affect the levels of aneuploidy and chromosome breakage in cultured human fibroblasts

Spontaneous micronucleus frequencies were measured in 11 human fibroblast strains, with early-passage cells that had never been frozen and with cells of comparable population doublings that had been cryopreserved in liquid nitrogen. The mean micronucleus frequency of the 11 strains increased from 14.0 +/- 0.7 to 20.4 +/- 1.8/1250 mononucleated cells (P = 0.002) after the freeze-thaw process. The nature of this increase in micronucleus frequency was examined using an immunodetection assay for the in situ identification of kinetochores in micronuclei. The increase in micronucleus frequency occurred primarily in the kinetochore-positive fraction, which is indicative of aneuploidy, but also by an increase in chromosome breakage in several strains. The findings were reproducible in repeat biopsies from two donors. Plating efficiencies of the 11 strains were studied during 1-9 and 10-20 population doublings from primary outgrowth, before freezing and again after freeze-thaw. The mean plating efficiency of frozen-thawed cells before nine doublings was significantly lower than that of cells of similar ages that had never been frozen (P = 0.004). The four strains that had a greater than 25% decrease in plating efficiency post freeze-thaw also had the highest aneuploidy index post freeze-thaw, suggesting that chromosomal imbalance contributes to the observed reduction in growth. We conclude that the genotype and culture manipulations of a fibroblast strain influence the outcome of the micronucleus assay.

Duodenal and antral mucosal prostaglandin E2 synthesis in a study of normal subjects and all stages of duodenal ulcer disease treated by H2 receptor antagonists

We tested the hypothesis that the production of prostaglandin E2 (PGE2) is impaired in duodenal ulcer disease and affected by treatment and healing. This was investigated by a study of maximal PGE2 synthesis rates in duodenal and antral mucosal biopsies obtained at endoscopy. The patients were divided into three groups. Group (a): endoscopically normal controls (n = 56); group (b): treatment controls (non-DU disease: gastric ulcer or oesophagitis treated by histamine H2 receptor antagonists) (n = 41); and group (c): patients with DU disease (n = 183) further subdivided into group (c1) active ulcer not on treatment (n = 47), (c2) treated active ulcer (n = 35), (c3) healed ulcer on treatment (n = 86), and (c4) healed ulcer not on treatment (n = 15). Group (a) synthesised (mean (SD] 106.6 (39.0) pg PGE2/mg wt of tissue from the duodenal bulb and 129.9 (56.9) from the second part of the duodenum. No difference was found between group (a) and (b) at either site. Group (c1) ulcer rim made 49.8 (22.7) and at all stages ulcer rim and scar made less than the control duodenal bulb (p less than 0.02). Uninvolved duodenal bulb form groups (c1) (63.4 (31.0], (c2) (83.6 (38.5], and (c3) (81.5 (31.1], however, also made significantly less than controls (p less than 0.02) and a similar though non-significant trend was seen in group (c4). Biopsies from the second part of the duodenum did not synthesise significantly less than the control group but a similar trend was noticed at each stage of ulcer treatment. Biopsies of control antrum synthesised 124.5 (32.2) but only 93.7 (44.2) in group (cl) (p < 0.005). All stages of duodenal ulcer healing were associated with a decreased capacity to synthesise the major prostaglandin PGE2 at the ulcer site and the uninvolved duodenal bulb and, in acute untreated duodenal ulcer, the uninvolved antrum. This decreased capacity may be the consequence of the disease process itself and not secondary to the treatment, indicating a basic pathophysiological abnormality which may explain the characteristic tendency of the disease to relapse.

Pressure-flow characteristics of coronary collaterals in dogs

In this study we utilized two methods to investigate the pressure-flow, P-F, relationship of the coronary collateral vessels in a beating, blood-perfused, isolated heart preparation. In the first method (free-flow method), 12 dog hearts were perfused at pressures ranging from 100 to 0 mmHg, whereas the retrograde flow (index of collateral flow) was measured on the circumflex coronary artery, LCA, against atmospheric pressure, first during autoregulation and then after maximum vasodilation. In the second method (back-pressure method), the back pressure to retrograde flow was varied from 0 to 100 mmHg, whereas the perfusion pressure to the remaining vessels was maintained constant at 100 mmHg. This procedure was performed on four hearts with and without embolization of the LCA by 25-microns spheres. The free-flow method demonstrated a linear P-F relationship with an average correlation coefficient, r, of 0.98. The pressure intercept was 1.7 +/- 1.2 mmHg. The back-pressure method yielded a relationship that was more curvilinear with an average pressure intercept of 13 mmHg without embolization and 38 mmHg with embolization. An analog of the coronary and collateral circulation was used to illustrate that, in the back-pressure method, changes in the coronary resistance at low pressures contributed to the nonlinearity of the collateral P-F characteristics and that the network formed between the collateral and coronary resistances was responsible for the higher pressure intercept value.

Communication attitudes and aging

This investigation compared the reported communication attitudes of 102 adults in six age groups. Participants completed the Inventory of Communication Attitudes which examines perceptions of self and others in a number of speaking situations. Discriminant analysis procedures were utilized to examine age group differences. Results indicated significant difference across age groups for perceptions of self and perceptions of others. The two age groups most frequently differentiated from the other groups were those persons in their twenties and those in their sixties.

COLONIZATION OF WESTERN WHEATGRASS (AGROPYRON SMITHII RYDB.) BY VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI DURING THE REVEGETATION OF A SURFACE MINE

Development of vesicular-arbuscular mycorrhizas and proliferation of roots of western wheat-grass (Agropyron smithii Rydb.) were investigated in a revegetated mine soil in southeastern Wyoming, USA. Total rooting density (root length per volume of soil) and spore frequency increased as a function of age of the reclamation (time elapsed since reseeding). Topsoil replaced during reclamation was apparently the primary source of mycorrhizal inoculum in the most recently reclaimed site. Seedlings growing on spoil material without topsoil were generally non-mycorrhizal, but mycorrhizal rooting density was not significantly correlated with the residual content of soil organic matter (an indicator of the proportion of topsoil in the growth media). Mycorrhizal colonization in sites up to three years old was minimal in spite of rapid increases in overall rooting density. Mean rooting density, mean degree of infection, and mean spore frequencies in older sites (five to seven years) were comparable to those of an adjacent undisturbed rangeland, but were highly variable. Mature, non-mycorrhizal specimens were observed, suggesting that A. smithii is not highly dependent on mycorrhizal infection for survival on this disturbed site.