Comparative effectiveness of denosumab, teriparatide, and zoledronic acid among frail older adults: a retrospective cohort study

The comparative effects of zoledronic acid, denosumab, and teriparatide for preventing hip fractures in frail older adults, especially those in nursing homes, were unknown. We found that denosumab and zoledronic acid may be as effective as teriparatide for hip fracture prevention in nursing home residents.

INTRODUCTION

Several non-oral drugs exist for osteoporosis treatment, including zoledronic acid (ZA), denosumab, and teriparatide. Little data exist on the comparative effectiveness of these drugs for hip fracture prevention in frail older adults. We examined their comparative effectiveness in one of the frailest segments of the US population-nursing home (NH) residents.

METHODS

We conducted a national retrospective cohort study of NH residents aged ≥ 65 years using 2012 to 2016 national US Minimum Data Set clinical assessment data and linked Medicare claims. New parenteral ZA, denosumab, and teriparatide use was assessed via Medicare Parts B and D; hip fracture outcomes via Part A; and 125 covariates for confounding adjustment via several datasets. We used inverse probability weighted (IPW) competing risk regression models to compare hip fracture risk between groups with teriparatide as the reference.

RESULTS

The study cohort (N = 2019) included 1046 denosumab, 578 teriparatide, and 395 ZA initiators. Mean age was 85 years, 90% were female, and 68% had at least moderate functional impairment. Seventy-two residents (3.6%) had a hip fracture and 1100 (54.5%) died over a mean follow-up of 1.5 years. Compared to teriparatide use, denosumab use was associated with a 46% lower risk of hip fracture (HR 0.54, 95% CI 0.29-1.00) and no difference was observed for ZA (HR 0.70, 95% CI 0.26-1.85).

CONCLUSIONS

Denosumab and ZA may be as effective as teriparatide for hip fracture prevention in frail older adults. Given their lower cost and easier administration, denosumab and ZA are likely preferable non-oral treatments for most frail, older adults.

Genetic correlations of milk fatty acid contents predicted from milk mid-infrared spectra in New Zealand dairy cattle

The objective of this study was to estimate genetic correlations among milk fatty acid (FA) concentrations in New Zealand dairy cattle. Concentrations of each of the most common FA, expressed as a percentage of the total FA, were determined by gas chromatography on a specific cohort of animals. Using this data set, prediction equations were derived using mid-infrared (MIR) spectroscopy data collected from the same samples. These prediction equations were applied to a large data set of MIR measurements in 34,141 milk samples from 3,445 Holstein-Friesian, 2,935 Jersey, and 3,609 crossbred Holstein-Friesian × Jersey cows, sampled an average of 3.42 times during the 2007-2008 season. Data were analyzed using univariate and bivariate repeatability animal models. Heritability of predicted FA concentration in milk fat ranged from 0.21 to 0.42, indicating that genetic selection could be used to change the FA composition of milk. The de novo synthesized FA (C6:0, C8:0, C10:0, C12:0, and C14:0) showed strong positive genetic correlations with each other, ranging from 0.24 to 0.99. Saturated FA were negatively correlated with unsaturated (-0.93) and polyunsaturated (-0.84) FA. The saturated FA were positively correlated with milk fat yield and fat percentage, whereas the unsaturated FA were negatively associated with fat yield and fat percentage. Our results indicate that bovine milk FA composition can be changed through genetic selection using MIR as a phenotypic proxy.

Changes in bone mineral density (BMD): a longitudinal study of osteoporosis patients in the real-world setting

In clinical practice, the frequency of patients achieving improved T-scores and the expected change in bone mineral density (BMD) according to osteoporosis drugs is unknown. We found that osteoporosis medications infrequently achieve improved femoral neck T-scores over 1.2 years. BMD increases were more often seen with IV bisphosphonates and denosumab.

PURPOSE

To determine the frequency of osteoporosis patients achieving improvement in T-scores and quantify the change in bone mineral density (BMD) over time according to osteoporosis medication use.

METHODS

The study included all patients receiving clinical care at United Osteoporosis Centers, Gainesville, GA, 1995-2015, who had at least two measures of femoral neck BMD (N = 1232). We evaluated successive pairs of BMD tests to describe the distribution of transitions between T-score categories. Generalized estimating equations were used to estimate %BMD change between successive pairs of BMD tests according to osteoporosis medication, adjusted for age, sex, height, weight, baseline BMD, previous fracture, and follow-up time.

RESULTS

Mean (±SD) age was 68 (±10) years, and 90% of patients were women. Mean baseline T-score was - 2.04 (± 0.85). In total, 1232 patients had 4918 pairs of successive BMD tests, with a mean 1.2 years (± 0.9) between assessments. Frequency of transition to an improved T-score category was 41% when prior T-score ≤ - 3.5, and 15% when prior T-score - 1.99 to - 1.50. Most individuals (69%) remained in the same T-score category. BMD increased 0.54% (95% CI 0.23-0.85%) with IV bisphosphonates and 1.23% (95% CI 0.56-1.90%) with denosumab, whereas no significant change was seen with oral bisphosphonates, teriparatide, or raloxifene.

CONCLUSIONS

Osteoporosis patients are unlikely to improve femoral neck T-scores over 1.2 years. Additional studies are needed to determine the optimal time to repeat BMD testing while receiving osteoporosis treatment and to determine whether fracture risk is reduced in patients who achieve target T-scores.

Defining hip fracture with claims data: outpatient and provider claims matter

Medicare claims are commonly used to identify hip fractures, but there is no universally accepted definition. We found that a definition using inpatient claims identified fewer fractures than a definition including outpatient and provider claims. Few additional fractures were identified by including inconsistent diagnostic and procedural codes at contiguous sites.

INTRODUCTION

Medicare claims data is commonly used in research studies to identify hip fractures, but there is no universally accepted definition of fracture. Our purpose was to describe potential misclassification when hip fractures are defined using Medicare Part A (inpatient) claims without considering Part B (outpatient and provider) claims and when inconsistent diagnostic and procedural codes occur at contiguous fracture sites (e.g., femoral shaft or pelvic).

METHODS

Participants included all long-stay nursing home residents enrolled in Medicare Parts A and B fee-for-service between 1/1/2008 and 12/31/2009 with follow-up through 12/31/2011. We compared the number of hip fractures identified using only Part A claims to (1) Part A plus Part B claims and (2) Part A and Part B claims plus discordant codes at contiguous fracture sites.

RESULTS

Among 1,257,279 long-stay residents, 40,932 (3.2%) met the definition of hip fracture using Part A claims, and 41,687 residents (3.3%) met the definition using Part B claims. 4566 hip fractures identified using Part B claims would not have been captured using Part A claims. An additional 227 hip fractures were identified after considering contiguous fracture sites.

CONCLUSIONS

When ascertaining hip fractures, a definition using outpatient and provider claims identified 11% more fractures than a definition with only inpatient claims. Future studies should publish their definition of fracture and specify if diagnostic codes from contiguous fracture sites were used.

Diuretic initiation and the acute risk of hip fracture

SUMMARY

We found the risk of hip fracture was transiently elevated around twofold shortly after initiation of a loop or thiazide diuretic drug in a case-crossover and case-control study. No statistical association was found following the initiation of a comparator medication: ACE inhibitors. Awareness of these short-term risks may reduce hip fractures.

INTRODUCTION

Little is known about the acute effects of initiating a diuretic drug on risk of fracture. We evaluated the relationship between initiating a diuretic drug and the occurrence of hip fracture.

METHODS

The study sample included 2,118,793 persons aged ≥50 years enrolled in The Health Improvement Network (THIN) between 1986 and 2010. The effect of a new start of a diuretic drug or comparator medication (ACE inhibitor) on risk of hip fracture was assessed using a case-crossover and case-control study during the 1-7, 8-14, 15-21, and 22-28 days following drug initiation.

RESULTS

Included were 28,703 individuals with an incident hip fracture over a mean of 7.9 years follow-up. In the case-crossover study, the risk of experiencing a hip fracture was increased during the first 7 days following loop diuretic drug initiation (OR = 1.8; 95 % CI, 1.2, 2.7). The elevated risk did not continue during the 8-14, 15-21, or 22-28 days following drug initiation. For thiazide diuretics, the risk of hip fracture was elevated 8-14 days after drug initiation (OR = 2.2; 95 % CI, 1.2, 3.9). No such association was observed in the 1-7, 15-21, or 22-28 days following thiazide drug initiation. ACE inhibitor initiation was not associated with a statistically significant increased risk of hip fracture. Similar results were observed using a case-control study.

CONCLUSIONS

The risk of hip fracture was transiently elevated around twofold shortly after the new start of a loop or thiazide diuretic drug. Awareness of these short-term risks may reduce hip fractures and other injurious falls in vulnerable adults.

Interfacial Exchange Coupling and the magnetization of Iron Oxide/Nickel Oxide Superlattices

The role of interfacial exchange coupling in the magnetic behavior of metal oxide materials has been investigated through the study of Fe3O4/NiO superlattices. We report results on a series of superlattices grown where one bilayer constituent was held to a fixed thickness while varying the other from single unit cell dimensions upward. High crystalline quality was confirmed by XRD, RHEED and neutron diffraction. Magnetization profiles show substantial deviations from bulklike iron oxide results, with an increase in domain rotation energies observed in the superlattices over that of bulk iron oxide (increasing with NiO layer thickness) indicating the strong nature of Fe3O4/NiO interfacial linkage. Neutron scattering at elevated temperatures shows that the NiO remains ordered above the 523 K bulk Néel temperature. This suggests that at least a portion of the NiO within a layer remains ordered well above the Néel temperature, with an increase in effective Néel transition temperature that approaches the Fe3O4 Curie temperature in the limit of very thin NiO layers. Although the exchange coupling dominates these effects, strain also plays an important role.

Does dietary protein reduce hip fracture risk in elders? The Framingham Osteoporosis Study

Association between dietary protein and fracture risk is unclear. We examined association between energy-adjusted protein intake and hip fracture risk in elders. The risk of hip fracture was reduced in upper quartiles of protein intake when compared with lowest quartile.

INTRODUCTION

Studies of the association between dietary protein intake and hip fracture risk are conflicting. Therefore, we examined protein intake and hip fracture risk in a population-based group of elderly men and women.

METHODS

Five hundred seventy-six women and 370 men from the Framingham Osteoporosis Study with no previous history of hip fracture completed Food Frequency Questionnaires. Energy-adjusted protein intake was evaluated as a continuous variable and as quartiles. Incidence rates and hazard ratios were calculated, adjusting for age, BMI, sex, and energy intake.

RESULTS

Among 946 participants (mean age 75 years), mean protein intake was found to be 68 gm/d. Increased protein intake was associated with a decreased risk of hip fracture compared to those in the lowest quartile of protein intake (Q2 HR = 0.70, Q3 HR = 0.56, and Q4 HR = 0.63; all p values ≥ 0.044), p for trend was 0.07. When a threshold effect was considered (Q2-4 vs Q1), intakes in the higher quartiles combined were associated with a significantly lower risk for hip fracture (HR = 0.63; p = 0.04).

CONCLUSION

Our results are consistent with reduced risk of hip fracture with higher dietary protein intake. Larger prospective studies are needed to confirm and extend this finding in elderly men and women.

Within-field damage and distribution patterns of the stalk borer, Eldana saccharina (Lepidoptera: Pyralidae), in sugarcane and a comparison with nematode damage

The occurrence of Eldana saccharina (Lepidoptera: Pyralidae) was monitored in grids represented by plots in 12 nematicide trials in South African sugarcane fields. The trials encompassed a total of eight plant cane crops and 22 ratoon crops and were situated within commercial cane fields. Several measurements were made to characterize the damage caused by E. saccharina. These included the number of internodes per stalk, the percentage of internodes damaged and the percentage of stalks damaged. The mapping of E. saccharina infestation in plant crops of sugarcane showed that the borders of the trials were as infested as the centre, indicating invasion from outside the field plus internal spread within the field. Ratoon crops were less infested than plant crops. This could be explained by a shorter ratoon crop cycle and by the fields having areas that were more suitable for the borer than elsewhere. The location of these preferred areas could be predicted from one ratoon crop to the next but was not related to the distribution of the borer in the plant crop. This situation was thought to explain the apparent stabilization of E. saccharina infestation in ratoon cane. Because the borer was found at harvest only in stalks with more than 14 to 16 internodes, it appeared that the oldest shoots, or the shoots with the greatest growth potential, attracted the insect, possibly due to their higher nitrogen content, which would stimulate growth. All the trials were on sandy soil, and crop loss from nematodes was greater than that caused by E. saccharina.

Mapping a quantitative trait locus for the concentration of beta-lactoglobulin in milk, and the effect of beta-lactoglobulin genetic variants on the composition of milk from Holstein-Friesian x Jersey crossbred cows

AIM

To identify quantitative trait loci (QTL) affecting the concentration of beta-lactoglobulin in milk, and to evaluate the effect of beta-lactoglobulin genetic variants on the concentration of fat, protein and casein in bovine milk.

METHODS

A herd of 850 F2 Holstein-Friesian x Jersey crossbred cows was produced through mating six Holstein-Friesian x Jersey F1 bulls of high genetic merit with F1 cows from the national herd. A total of 1,610 herd-test records from 556 second-parity crossbreds were analysed. The concentration of fat, protein and casein in milk was measured at peak, mid- and late lactation, during the production seasons of 2003-2004 and 2004-2005. Liveweight was measured daily. DNA from the F2 animals, their F1 dams and sires, and selected grandsires was genotyped across the genome, initially with 285 microsatellite markers, and subsequently with 6,634 single nucleotide polymorphisms (SNP).

RESULTS

A highly significant QTL for the concentration of beta-lactoglobulin in milk was identified, which coincided with the position of the beta-lactoglobulin gene on bovine Chromosome 11. No other consistently significant QTL for the concentration of beta-lactoglobulin in milk were detected. Cows with the BB beta-lactoglobulin genotype produced milk with a 30% lower concentration of beta-lactoglobulin than cows with the AA genotype. The beta-lactoglobulin polymorphism also explained variation in the proportion of casein in total protein. In addition, the percentage of fat was higher for BB than AA animals, whereas the percentage of total protein, mean daily milk yield and liveweight did not differ between AA and BB animals.

CONCLUSIONS

A significant QTL determining the concentration of beta-lactoglobulin in milk was identified. Selection of animals for the beta-lactoglobulin B-allele may enable the production of milk naturally enriched for casein, thus allowing a potential increase in the yield of cheese. There may be additional future value in production of bovine milk more like human milk, where decreasing the concentration of beta-lactoglobulin is desirable.

Application of the National Osteoporosis Foundation Guidelines to postmenopausal women and men: the Framingham Osteoporosis Study

We applied the 2008 National Osteoporosis Foundation (NOF) Guidelines to Framingham Osteoporosis Study participants and found nearly one half of Caucasian postmenopausal women and one sixth of men aged 50 years and older would be recommended for osteoporosis treatment. Given the high proportion of persons recommended for treatment, NOF Guidelines may need to be re-evaluated with respect to budget impact.

INTRODUCTION

Little is known about the public health impact of the NOF Guidelines. Therefore, we determined the proportion of US Caucasians recommended for treatment of osteoporosis according to NOF Guidelines (2003 and 2008).

METHODS

One thousand nine hundred and forty-six postmenopausal women and 1,681 men aged > or =50 years from the Framingham Study with information on bone mineral density (1987-2001) were included. Information on clinical predictors was used to estimate the 10-year probability of hip and major osteoporotic fracture by FRAX (version 3.0).

RESULTS

Overall proportion of women meeting treatment criterion was less when the 2008 NOF Guidelines were applied (41.1%) compared with 2003 Guidelines (47.8%). The proportion of women aged <65 years meeting treatment criterion was much less when applying 2008 Guidelines (23.1% in 2003, 8.3% in 2008), whereas the proportion of women aged >75 years increased slightly (78.3% in 2003, 86.0% in 2008). Seventeen percent of men aged > or =50 years met treatment criterion (2.5% aged 50-64 years, 49.8% aged >75 years).

CONCLUSIONS

Nearly one half of Caucasian postmenopausal women and one sixth of men aged 50 years and older would be recommended for osteoporosis treatment according to 2008 NOF Guidelines. Given the high proportion of persons recommended for treatment, NOF Guidelines may need to be re-evaluated with respect to budget impact.

Ovarian and IGF-I axis control of mammary development in prepubertal heifers

Although much is known about the endocrine control of bovine mammary development, most heifer work has focused on periods near the time of puberty or during gestation. However, we have found that ovariectomy in the prepubertal period also markedly impacts mammary development well before the onset of estrus would have normally occurred. Interactions between the pituitary and ovary to control udder development are mediated at least in part via alteration in concentrations of local IGF-I axis molecules within the developing mammary gland. For example, in heifers treated with growth hormone or estrogen, expression of IGF-I binding proteins (IGFBP-3) protein was reduced, thus effecting an increase in free IGF-I. Ovariectomized heifers had reduced rates of epithelial cell proliferation, fewer IGF-I receptors, and less local IGF-I. Mammary tissue expression of fibronectin was increased in ovariectomized heifers, but laminin expression was higher in controls. Thus, alterations in specific extracellular matrix proteins likely impact heifer mammary development. As a result, we have initiated calfhood studies. At 30 days of age, it is difficult to detect parenchymal tissue in the udder. Only a thin cord of parenchymal tissue (150 mg per gland) is discernible. By 75 days of age, a rounded, walnut-like mass of mammary parenchymal tissue becomes very evident and at 90 days of age, this mass of tissue has grown to approximately 10 g, a approximately 60-fold increase. At 2 months of age, most proliferating epithelial cells (>92%) are confined to a population of light and intermediate-staining parenchymal cells. Between 2 and 5 months of age, a dark-staining cell population markedly emerges, but these dark cells were rarely labeled with bromodeoxyuridine (BrdU) and are likely to represent a more differentiated or committed cell lineage. The coordinated change in the proportions of each cell type suggests a progression from light-, to intermediate-, to dark-staining cell phenotypes. We are currently focusing on the importance of the ovary and mammary tissue synthesis of estrogens on emergence of specific populations of putative mammary stem cells.

Hippocampal theta oscillations and classical conditioning

Studies are reviewed that support a hypothesized role for hippocampal theta oscillations in the neural plasticity underlying behavioral learning. Begun in Richard F. Thompson's laboratory in the 1970s, these experiments have documented a relationship between free-running 3- to 7-Hz hippocampal slow waves (theta) and rates of acquisition in rabbit classical nictitating membrane (NM) conditioning. Lesion and drug manipulations of septohippocampal projections have affected NM and jaw movement conditioning in ways consistent with a theta-related brain state being an important modulator of behavioral acquisition. These findings provide essential empirical support for the recently developed neurobiological and computational models that posit an important role for rhythmic oscillations (such as theta) in cellular plasticity and behavioral learning.

A local increase in the mammary IGF-1: IGFBP-3 ratio mediates the mammogenic effects of estrogen and growth hormone

A single epithelium-free mammary fat pad was surgically prepared in each of twenty-five one-month-old, Friesian heifers. At 18 mo of age, heifers were randomly assigned to one of four treatment groups. Treatments were: control (C), growth hormone (GH), estrogen (E) or growth hormone + estrogen (GE). Hormones were administered for 40 hr before the animals were sacrificed to provide mammary samples of parenchyma (PAR), intact fat pad (MFP), and epithelium-free or "cleared" fat pad (CFP). IGF-1 and IGF binding protein-3 (IGFBP-3) mRNA was highest in CFP and MFP whereas the protein products were highest in PAR. IGFBP-2, a 28-kDa IGFBP and a 24-kDa IGFBP were more abundant in CFP and MFP. E and GH increased incorporation of [(3)H]thymidine into DNA of PAR. Incorporation of [(3)H]thymidine into the DNA of MFP or CFP was minimal. Coincident with the changes observed in mammary epithelial proliferation, E increased IGF-1 protein in MFP and PAR, and to a lesser extent in CFP. E tended to increase IGF-1 mRNA levels in MFP, but not CFP implying that the regulation of IGF-1 expression is modulated by adjacent epithelium. GH and E reduced IGFBP-3 protein in PAR and increased the 24-kDa IGFBP in CFP and MFP. Increased proliferation of mammary parenchymal cells was associated with increased IGF-1 and reduced IGFBP-3 protein in mammary tissue. An increase in the ratio of mammary IGF-1: IGFBP-3 likely increases the proportion of the mammary IGF-1 available to stimulate proliferation. These data also indicate that stromal: epithelial interactions regulate the IGF-1 axis in mammary tissue.

Medial septal microinfusion of scopolamine disrupts hippocampal activity and trace jaw movement conditioning

This study investigated the effects of microinfusion of scopolamine into the medial septum (MS Scp) on hippocampal neurophysiology and learning of the rabbit's classically conditioned jaw movement response. The percentage of hippocampal theta slow waves (2-8 Hz) decreased after drug infusion in the MS Scp group but did not change in control groups that received infusion of saline into the MS or scopolamine into the cortex. Unit recordings from the MS Scp group showed significantly smaller conditioning-related hippocampal neural responses than seen in controls, and during conditioning, rabbits in the MS Scp group took significantly longer to reach learning criterion than either control group. Thus, the neural and behavioral impairments previously reported for systemic muscarinic blockade were reproduced by microinfusions restricted to the medial septal nucleus.

Ethnic differences in allelic associations of the interleukin-1 gene cluster in South African patients with inflammatory bowel disease (IBD) and in control individuals

The allelic frequencies of TaqI, PstI, and variable number of tandem repeat (VNTR) polymorphisms of the IL-1beta, IL-1 receptor (IL-1Re), and IL-1 receptor antagonist (IL-1Ra) respectively, were investigated in black and white patients with inflammatory bowel diseases (IBD) and compared with control individuals. Plasma concentrations of IL-1beta and IL-1Ra were also determined in these individuals. The IL-1beta TaqI(-) allele was significantly more frequent in 50 white IBD patients (60%) compared with 47 white controls (17%), and 20 black patients (20%) (P=0.00001 and P=0.0001, respectively). The IL-1Re PstI(-) allele was significantly more frequent in 20 black patients (75%) compared with 50 white patients (44%) (P=0.0001). The frequency of the IL-1Ra 240-bp allele was lower in black (12%) compared with white controls (25%), (P=0.0151), and the 410-bp allele was more frequent in black (87%) compared with white (73%) controls (P=0.0096). Linkage disequilibrium was found in black individuals homozygous for the 410-bp allele of IL-1Ra, and the PstI(-) allele of IL-1Re (84%) (P=0.0032). There was a significantly increased level of IL-1Ra in black patients compared with white patients and black controls (P=0.0006 and P=0.0008, respectively). The population differences in allelic frequencies of the IL-1 gene cluster and IL-1Ra concentrations suggest that genetic and environmental factors play an important role in susceptibility to IBD.

Medial septal microinfusion of scopolamine disrupts hippocampal activity and trace jaw movement conditioning

This study investigated the effects of microinfusion of scopolamine into the medial septum (MS Scp) on hippocampal neurophysiology and learning of the rabbit's classically conditioned jaw movement response. The percentage of hippocampal theta slow waves (2-8 Hz) decreased after drug infusion in the MS Scp group but did not change in control groups that received infusion of saline into the MS or scopolamine into the cortex. Unit recordings from the MS Scp group showed significantly smaller conditioning-related hippocampal neural responses than seen in controls, and during conditioning, rabbits in the MS Scp group took significantly longer to reach learning criterion than either control group. Thus, the neural and behavioral impairments previously reported for systemic muscarinic blockade were reproduced by microinfusions restricted to the medial septal nucleus.

Scopolamine disruption of behavioral and hippocampal responses in appetitive trace classical conditioning

Twelve young rabbits (3-6 months; Oryctolagus cuniculus) were classically conditioned in a trace jaw movement paradigm (300 ms tone, 450 ms trace, 200 ms intraoral water) after implantation of electrodes into area CA1 of dorsal hippocampus. Rabbits were divided into two groups and administered either 0.5 mg/kg scopolamine hydrobromide (HBr) or 0.5 mg/kg scopolamine methylbromide (MBr) subcutaneously before daily training sessions. Rabbits given HBr took significantly more trials to reach a behavioral criterion of eight conditioned responses in any nine consecutive trials than rabbits given MBr (P = 0.03). Conditioned, but not unconditioned, rhythmic jaw movement responses of the HBr group were of a lower frequency (Hz) than those of MBr rabbits (P = 0.02). The magnitude of hippocampal conditioning-related responses across the first 3 days of training was significantly smaller for HBr rabbits than for MBr rabbits (P = 0.02). These effects of central cholinergic blockade are similar to those reported for undrugged aging rabbits trained in the same paradigm (Seager MA, Borgnis RL, Berry SD. Neurobiol. Aging 1997;18(6):631 639).

Hippocampal age differences reoccur after modification of stimulus configurations in rabbit jaw movement conditioning

Rabbits of two age groups, young (3-7 months; n = 7) and aging (40-49 months; n = 7), were implanted with chronic recording electrodes in area CA1 of dorsal hippocampus and trained in a delay conditioned jaw movement (CJM) paradigm (after previously reaching criterion in a trace CJM paradigm with the same conditioned stimulus and unconditioned stimulus). Unlike results from the trace experiment, there was no significant difference in trials to behavioral criterion between the two age groups. There were large, but temporary, differences in the magnitude of conditioning-related hippocampal neural responses early in delay training. Aging rabbits' hippocampal responses were significantly smaller on Day 2 of delay training than corresponding responses of young rabbits (p = 0.0008). It is important to note that neural differences were not observed on Days 1 and 3 of delay training or at criterion performance in the prior trace conditioning. These results are interpreted in terms of age-related differences in hippocampal responsiveness to changes in biologically significant stimulus configurations.

Delayed acquisition of behavioral and hippocampal responses during jaw movement conditioning in aging rabbits

Young (3-7 months; n = 7) and aging (40-49 months; n = 7) rabbits (Oryctolagus cuniculus) were classically conditioned in a trace jaw movement paradigm (300 ms tone, 450 ms trace, 200 ms intraoral water) after implantation of electrodes into area CAI of dorsal hippocampus. Aging rabbits took significantly more trials to reach a behavioral criterion of 8 conditioned responses in any 9 consecutive trials than young rabbits (p = 0.04), and their conditioned, but not unconditioned, jaw movement responses were of a lower frequency than those of young rabbits (p = 0.02). Early in training, aging rabbits' hippocampal responses were significantly smaller just before water onset than corresponding responses of young rabbits (p = .03). The magnitude of this response was negatively correlated with trials to criterion (r = -0.60, p = 0.03). These results are interpreted in terms of age-related differences in the hippocampal contribution to jaw movement learning.

Age-dependent taste preferences in rabbits for a .025% sodium saccharin solution: preliminary findings

Classical conditioning of rhythmic jaw movements in rabbits is an accepted model of associative learning that may be useful in assessing age-related changes in learning and motivation. A saccharin solution has been thought to be rewarding to rabbits and is often used as an unconditioned stimulus (US). To determine whether age-related differences in preference for saccharin exist, we assessed (a) saccharin versus water preferences and (b) fluid intake level differences (which might account for differing drive levels) in young (4-6 months) and old (31-69 months) rabbits. Young animals demonstrated a significant preference for water, whereas old animals strongly preferred the saccharin solution. There were no differences between young and old rabbits in overall fluid intake. These results suggest that whereas saccharin may be an appetitive US for old rabbits, it may be aversive to young ones. Thus aging may affect the incentive value of rewarding stimuli, complicating the interpretation of interactions among aging, learning, and motivational processes.

Hippocampal plasticity during jaw movement conditioning in the rabbit

Hippocampal CA1 unit responses were recorded during classical conditioning of rhythmic jaw movements in New Zealand White rabbits. Training was accomplished using a 1 kHz tone as the conditioned stimulus (CS) and 1 ml of sweetened water as the unconditioned stimulus (US). The interstimulus interval was 250 ms. Daily sessions consisted of 48 paired trials and six tone alone test trials, with an intertrial interval averaging 60 s. Controls were given explicitly unpaired stimuli. Unit and behavioral conditioned responses developed very rapidly in the trained group, but did not occur in controls. Averaged unit poststimulus histograms showed a correspondence between rhythmic cell discharges and the periodicity of the behavioral conditioned response after training. The results are discussed in relation to a hippocampal role in the modulation of learned movement patterns.

Functional status and well-being of patients with chronic conditions. Results from the Medical Outcomes Study

Enhancing daily functioning and well-being is an increasingly advocated goal in the treatment of patients with chronic conditions. We evaluated the functioning and well-being of 9385 adults at the time of office visits to 362 physicians in three US cities, using brief surveys completed by both patients and physicians. For eight of nine common chronic medical conditions, patients with the condition showed markedly worse physical, role, and social functioning; mental health; health perceptions; and/or bodily pain compared with patients with no chronic conditions. Each condition had a unique profile among the various health components. Hypertension had the least overall impact; heart disease and patient-reported gastrointestinal disorders had the greatest impact. Patients with multiple conditions showed greater decrements in functioning and well-being than those with only one condition. Substantial variations in functioning and well-being within each chronic condition group remain to be explained.

Scopolamine disruption of septo-hippocampal activity and classical conditioning

Sixteen New Zealand White rabbits were implanted with multiple-unit recording electrodes in the hippocampus and lateral septum. Animals received either scopolamine hydrobromide (HBr) or scopolamine methylbromide (MBr, 1.5 mg/kg sc) prior to nictitating membrane conditioning. Slow wave analysis indicated that HBr reduced 5- to 8-Hz and increased 9- to 12-Hz hippocampal activity and increased 1- to 4-Hz activity in both hippocampus and lateral septum. Integrated unit activity from the HBr group showed suppression of responses in septum and hippocampus during learning, whereas the MBr group developed conditioned responses in both structures. Behavioral findings indicated that HBr took longer to reach criterion (M = 329.5 +/- 45.3) than MBr (M = 120.2 +/- 16.0). This experiment showed that centrally active anticholinergic drugs alter the patterns of neuronal activity in the septo-hippocampal region that predict and accompany normal learning. Such drugs delay behavioral acquisition as well, a result suggesting a modulatory role for this brain system in the acquisition phase of classical conditioning.

Water deprivation optimizes hippocampal activity and facilitates nictitating membrane conditioning

The effects of water deprivation on hippocampal responsiveness and behavior during nictitating membrane (NM) conditioning were assessed in 12 New Zealand White rabbits (Oryctolagus cuniculus). The results showed that water deprivation produced a significant shift in electroencephalographic (EEG) frequencies such that deprived rabbits had a higher proportion of 2-8 Hz activity than did ad-lib controls. In subsequent NM training, the rabbits took significantly fewer trials to reach criterion (M = 66 vs. M = 117). A correlation coefficient quantitatively describing the relation between pretraining EEG patterns and subsequent learning rate was highly significant (r = .84). Multiple-unit analyses indicated that deprivation enhanced hippocampal responsiveness to the conditioning stimuli, especially early in training. It was concluded that the hippocampus is responsive to motivational level and that one role of the hippocampus is in the nonassociative, modulatory processes that affect the rate of conditioning.

Water deprivation optimizes hippocampal activity and facilitates nictitating membrane conditioning

The effects of water deprivation on hippocampal responsiveness and behavior during nictitating membrane (NM) conditioning were assessed in 12 New Zealand White rabbits (Oryctolagus cuniculus). The results showed that water deprivation produced a significant shift in electroencephalographic (EEG) frequencies such that deprived rabbits had a higher proportion of 2-8 Hz activity than did ad-lib controls. In subsequent NM training, the rabbits took significantly fewer trials to reach criterion (M = 66 vs. M = 117). A correlation coefficient quantitatively describing the relation between pretraining EEG patterns and subsequent learning rate was highly significant (r = .84). Multiple-unit analyses indicated that deprivation enhanced hippocampal responsiveness to the conditioning stimuli, especially early in training. It was concluded that the hippocampus is responsive to motivational level and that one role of the hippocampus is in the nonassociative, modulatory processes that affect the rate of conditioning.

Scopolamine disruption of septo-hippocampal activity and classical conditioning

Sixteen New Zealand White rabbits were implanted with multiple-unit recording electrodes in the hippocampus and lateral septum. Animals received either scopolamine hydrobromide (HBr) or scopolamine methylbromide (MBr, 1.5 mg/kg sc) prior to nictitating membrane conditioning. Slow wave analysis indicated that HBr reduced 5- to 8-Hz and increased 9- to 12-Hz hippocampal activity and increased 1- to 4-Hz activity in both hippocampus and lateral septum. Integrated unit activity from the HBr group showed suppression of responses in septum and hippocampus during learning, whereas the MBr group developed conditioned responses in both structures. Behavioral findings indicated that HBr took longer to reach criterion (M = 329.5 +/- 45.3) than MBr (M = 120.2 +/- 16.0). This experiment showed that centrally active anticholinergic drugs alter the patterns of neuronal activity in the septo-hippocampal region that predict and accompany normal learning. Such drugs delay behavioral acquisition as well, a result suggesting a modulatory role for this brain system in the acquisition phase of classical conditioning.

Medial septal lesions retard classical conditioning of the nicitating membrane response in rabbits

Lesions of the medial septum were produced in 7 of 14 rabbits prior to classical conditioning of the nictitating membrane response. Lesions significantly altered the hippocampal electroencephalogram, attenuated conditioned hippocampal unit responses, and slowed the behavioral rate of acquisition. The contrast of the behavioral results with those of studies of massive septal or hippocampal ablation suggests a functional subdivision of the septo-hippocampal system in learning.

Analysis of temporal relations among units and slow waves in rabbit hippocampus

Arrays of triple microelectrodes were stereotaxically lowered into CA1, CA3 and dentate areas of the dorsal hippocampal formation in anesthetized rabbits. Recordings of action potentials and waves were analyzed on a PDP-11 computer using auto-, cross-, and multiple-correlation programs to determine temporal relations during 90 sec samples of spontaneous activity. It was found that temporal periods of neuronal firing and inhibition were strongly related to the pattern of waves. During periods of high amplitude synchronous waves (theta), the correlation between the activities of different groups of neurons was directly related to the periodicity of the wave. During instances of lower amplitude, desynchronous wave activity, the correlations between spikes recorded from those same cells were less periodic, varying according to the amount of wave synchrony. Variations in wave synchrony due to anatomical location, eserine effects, or spontaneous fluctuations under anesthesia produced corresponding variations in the relations between the activities of different groups of neurons. It is suggested that these relations between neuronal activity and gross waves may be implicated in processes which are at the basis of learning and memory.

Prediction of learning rate from the hippocampal electroencephalogram

Samples of spontaneous electroencephalographic (EEG) activity from the dorsal hippocampus of rabbits were recorded immediately before classical conditioning of the nictitating membrane response. Computer analysis revealed a significant predictive relationship between EEG frequency characteristics and the subsequent rate of learning.