The ultrasonic assessment of osteopenia as defined by dual X-ray absorptiometry

Dual X-ray absorptiometry (DXA) studies of bone mineral density (BMD) of the lumbar spine and femoral neck were compared with measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound (VOS) in the calcaneus in 300 pre- and postmenopausal women (mean age 53 years). The women were referred for evaluation of possible osteopenia as defined by DXA. The ability of ultrasound measurements to predict osteopenia in women was compared with the ability of lumbar spine and femoral neck DXA scans to predict osteopenia in the hip and spine. A new ultrasound parameter obtained by combining BUA and VOS (combined attenuation and velocity (CAV)) was also evaluated. Linear regression analysis of the three ultrasound parameters and lumbar spine and femoral neck BMD gave weak but statistically significant correlations (r = 0.45-0.54). The correlation between spine and femoral neck BMD was statistically significantly better (r = 0.72). Receiver-operating characteristic (ROC) analysis was used to investigate the sensitivity and specificity of ultrasound measurements in predicting patients with osteopenia. The areas under the ROC curves ranged from 0.64 to 0.75 and ultrasound parameters were shown to be poor at predicting osteopenia as defined by DXA. The ability of lumbar spine and femoral neck DXA measurement to predict osteopenia in the hip and spine, respectively, was statistically significantly better than any of the ultrasound parameters. Ultrasound measurements in the calcaneus did not appear to identify accurately patients with osteopenia defined by DXA measurements of bone density in the axial and appendicular skeleton.

Clinical implications of depression in rheumatoid arthritis

The clinical implications of depression in the context of rheumatoid arthritis are described. An overview of the diagnostic criteria for depression is provided, with specific focus on major depression and the associated subtypes. The neurobiological literature on major depression is briefly reviewed and the implications of the depression literature for the care of persons with rheumatoid arthritis are discussed.

Purification and immunochemical properties of human Na,K-ATPase alpha subunits and formic acid-derived polypeptide fragments

In this study, alpha (alpha) isoform proteins were purified from the partially purified Na,K-ATPase by SDS-PAGE and electroelution. Peptide mapping showed subtle biochemical differences between alpha subunit proteins of rat and human origin. The purified alpha proteins were treated with formic acid, the cleaved polypeptide fragments were separated by SDS-PAGE, the bands corresponding to 40, 50, and 60 kDa were excised, and the proteins were electroeluted. The purified 40, 50, and 60 kDa polypeptides were essentially homogeneous, and were used for preparation of polyclonal antibodies in rabbits. The antisera to alpha proteins (R alpha) and 60 & 40 kDa polypeptides (R60 & R40) were obtained and characterized by Western blotting. All three antisera were highly specific, since they cross-reacted with only the 100 kDa bands of the crude brainstem homogenates, of the axolemma, and of the cerebral cortex synaptosomes and microsomes. R alpha and R40 were successfully used for immunohistochemical staining of fibers in the white matter of the human brain frontal cortex. These antisera were not isoform-specific, they cross-reacted with 40, 50, and 60 kDa polypeptides as well as the three alpha bands.

Cognitive-behavioral approaches to pain management in rheumatoid arthritis

The purpose of this article is to review the literature on the topic of cognitive-behavioral approaches to pain management for persons with rheumatoid arthritis. Existing studies offer support for the usefulness of cognitive-behavioral techniques, but methodologic limitations were identified. Although the core element in rheumatoid arthritis pain management is optimal rheumatologic care, an important role also exists for strategies that seek to reduce the cognitive-evaluative aspects of arthritis pain.

ATP dependence of K-Cl cotransport in dog red blood cells

Swelling-induced K-Cl cotransport in resealed dog red blood cell ghosts requires the presence of an ATP-generating system (G. C. Colclasure and J. C. Parker. J. Gen. Physiol. 100: 1-10, 1992). The present study shows that the endogenous adenine nucleotide present in the dog ghosts is sufficient to activate K-Cl cotransport, provided that creatine phosphate is incorporated in them. Creatine kinase is not required, because dog red blood cells, unlike those of humans, possess this enzyme. Although some ATP appears to be required for K-Cl cotransport by dog ghosts, an excess of this nucleotide is inhibitory. Creatine phosphate appears to play a special role in generating the ATP required for activation of K-Cl cotransport. If ghost ATP content is manipulated in the absence of creatine phosphate, by simply adding ATP to the hemolysate, no stimulation of K-Cl cotransport occurs. On the other hand, when creatine phosphate is present, K-Cl cotransport is activated. The results are discussed in relation to current views regarding the role of ATP in activation of K-Cl cotransport and the concept of the "phosphocreatine shuttle."

Relative formation of dichloroacetate and trichloroacetate from trichloroethylene in male B6C3F1 mice

The hepatocarcinogenicity of trichloroethylene (TRI) has been attributed to the metabolite trichloroacetate (TCA). However, mice also form dichloroacetate (DCA) and trichloroethanol (TCE) as metabolites of TRI. TCA and DCA have both been shown to induce hepatic tumors in mice. This study was undertaken to measure the kinetics of TCA and DCA formation in the B6C3F1 mouse using doses of TRI ranging from 0.38 to 15 mmol/kg and TCA at doses of 0.03 to 0.61 mmol/kg. The formation and elimination of TCA and DCA have been found to be nonlinear with the dose of TRI. Quantifiable levels of DCA were found in blood with doses above 0.76 mmol/kg TRI. The peak concentration of DCA did not show an appreciable change with an increased dose; however, the area under the curve (AUC) increased linearly with respect to the dose of TRI. Both peak concentration and AUC of TCA and TCE increased in a linear manner to a dose of 3.8 mmol/kg. The kinetics of TCA elimination following doses of TCA were similar to those found for TCA following doses of TRI. A significant dose-dependent partitioning of TCA into blood over liver was found at the higher doses of TRI and TCA investigated. Binding of TCA to plasma constituents accounted for this distributional pattern. Prior work has documented that DCA can be formed from TCA. However, the AUC for DCA following TRI exceeds that predicted from the formation of TCA from TRI. Additional pathways would, therefore, appear to account for the formation of DCA. Results from this investigation suggest that sufficient concentrations of DCA appear to be formed and may contribute to the hepatocarcinogenicity of TRI.

In defense of cell volume?

Most cells react vigorously to perturbations in their fluid volume. Although the responses themselves have been well described, little is known about how the volume stimulus is detected and transduced. The relevance of volume-activated phenomena in vitro to volume homeostasis in vivo is not clear. It can be debated whether cells are truly responding to changes in their volume. Perhaps they are reacting to changes in the concentration of a cytoplasmic constituent. This review calls attention to recent literature bearing on these subjects and concludes that, in most cases, cells are not defending their volume but their concentration of cytosolic macromolecules.

Estimating oil spill characteristics from oil heads in scattered monitoring wells

The results are presented of a comparison of four different methods of interpolating observed hydrocarbon depths in monitoring wells, as well as a comparison of different methods of selecting sampling points for interpolation. The results provide criteria for selecting one interpolation method over another, under different scenarios. The methods analyzed are: (1) inverse-distance weighting; (2) punctual kriging; (3) minimum surface curvature; and (4) Akima's quintic polynomial.

Dual X-ray absorptiometry: a comparison between fan beam and pencil beam scans

The recent introduction of dual X-ray absorptiometry (DXA) systems with fan beam instead of conventional pencil beam scanning geometry represents a significant technical advance in bone densitometry. This report describes phantom and in-vivo studies of the effect of the change in beam configuration on DXA measurements. Fan beam and pencil beam measurements acquired on one of the new generation scanners, the Hologic QDR-2000, were compared with scans performed on an earlier pencil beam model, the Hologic QDR-1000. The variation with height above the scanning table of fan beam measurements of an anthropomorphic spine phantom were: bone mineral content (BMC): -3.1% cm-1; projected area (AREA): -2.8% cm-1; bone mineral density (BMD): -0.2% cm-1. For pencil beam scans the magnitude of height variation was less than 0.1% cm-1. QDR-2000 fan and pencil beam scan results for 20 volunteers correlated closely with QDR-1000 pencil beam data (r = 0.966-0.998). For BMD measurements on the spine and hip, differences between fan and pencil beam data were consistent with the errors expected from measurement precision. For AREA and BMC data, however, larger differences were observed with individual deviations which correlated with body habitus of the subjects. Although the change from pencil to fan beam geometry significantly affected AREA and BMC data, the effect on the clinically more important BMD measurements was negligibly small.

Pseudotumor cerebri: a review

Pseudotumor cerebri (PTC) is a syndrome seen more frequently in young, obese women defined by increased intracranial pressure without obstruction of the ventricular system. Normal neurodiagnostic studies, normal cerebrospinal fluid (CSF) contents, papilledema in one or both eyes, and normal mental status should also be recognized. Although the disorder has been associated with drugs, endocrinopathies, compromised nutritional status and other disease states, no underlying disorder is uniformly present.

Urea alters set point volume for K-Cl cotransport, Na-H exchange, and Ca-Na exchange in dog red blood cells

Urea equilibrates rapidly across the red blood cells of mammals. It was speculated that urea might affect the cell volume sensor by virtue of its properties as a protein perturbant. At concentrations of 0.1-0.6 M, urea caused a decrease in the set points for shrinkage-induced Na-H exchange, swelling-induced K-Cl cotransport, and swelling-induced Ca-Na exchange of dog red blood cells. Okadaic acid opposed the action of urea on all three pathways. The effects were reversible and not due to cyanate. Formamide and acetamide had actions similar to urea but not as potent. Equimolar concentrations of methanol had no effect. The coordinated influence of urea on three separate volume-activated transporters suggests that it acts on a mutual regulatory system that senses and transduces volume stimuli.

Immunohistochemical localization of amyloid beta-protein deposits in extracerebral tissues of patients with Alzheimer's disease

An autopsy study was conducted on patients with Alzheimer's disease in order to explore the possibility of amyloid beta-protein deposits in tissues other than the brain. Immunoperoxidase staining techniques were employed using an amyloid beta-protein antiserum as primary antibody; paraffin sections of kidney, liver, heart, lung, spleen, bone marrow, colon, stomach, adrenal, thyroid, and brain were examined. Our autopsy cases were divided into two groups. The first group comprised 10 patients with Alzheimer's disease. The second group consisted of eight control cases, of age-matched individuals, that died of unrelated causes and showed no clinicopathologic evidence of Alzheimer's disease. Identification was made of strong, although focal, positive staining in two kidneys and one lung of three different patients with Alzheimer's disease. All other tissues, including the control cases, showed negative staining.

Biopsychosocial contributions to the management of arthritis disability. Blueprints from an NIDRR-sponsored conference

The contributions of MACs and RRTCs to the generation of arthritis-related biopsychosocial research over the last 15 years have been enormous. However, the assimilation of biopsychosocial concepts into mainstream clinical practice, professional education, and public awareness will require a sustained national effort.

Relationship of pain behavior to disease activity and health status in rheumatoid arthritis

The purpose of the study was to investigate the contributions of disease activity, health status, and self-efficacy to the pain behavior exhibited by patients with rheumatoid arthritis. Measures included the Arthritis Impact Measurement Scales, the Arthritis Self-Efficacy Scale, a visual analogue scale for pain, and the McGill Pain Questionnaire. Joint counts and ratings of pain behavior also were obtained. All measures were collected at both baseline and 6 months. Hierarchical multiple regression analyses revealed that disease activity, as measured by joint count, was significantly related to a modified pain behavior index at both time intervals. With joint count entered into the regression model, no other variable consistently increased the predictive accuracy of the model. There were no significant correlations between the modified pain behavior index and either the visual analogue scale for pain or the McGill Pain Questionnaire scores. The results suggest that pain behavior in male rheumatoid arthritis patients is more closely related to disease activity than to self-reported pain, health status, or perceived self-efficacy.

Amyloid deposition in Alzheimer's disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, accounts for approximately 60 percent of all victims of dementia and affects greater than 10 percent of the population over 65 years old. Although the cause is unknown, there is evidence that beta-amyloid plays an important role in its pathogenesis. The deposition of this type of amyloid in the brain and its implications in AD are discussed.

Blood-to-tissue clearance vs. lymph analysis in determining capillary transport characteristics for albumin in skin

The blood-to-tissue clearance of radioactive albumin and a lymphatic flux analysis were used to evaluate the transport properties of albumin in the canine hindpaw. A prenodal lymphatic was cannulated, and lymph was collected for a 2-h control period. Thereafter venous pressure was elevated between 7 and 31 mmHg. After 2 h of increased venous pressure, the radioactive tracer was given intravenously. During the next 2 h lymph was sampled, and at the end of this time tissue and blood samples were obtained. The experiments showed that, of the tracer filtered in excess of control at increased venous pressure, an estimated 21% was cleared via the lymphatics and 79% was retained in the tissue. As a percentage of total tracer flux at increased venous pressure, 9% (measured) was drained by lymph and 91% was retained in the tissue. Of the fluid filtered in excess of control at increased capillary pressure, 70% (measured) was drained via the lymphatics and 30% was retained in the tissue in the same period. Twice the amount of endogenous albumin filtered across the capillary wall was drained via the lymphatics during the experimental period. The lymphatic washout of endogenous albumin from the interstitium will cause an underestimation of the capillary reflection coefficient and overestimation of the permeability-surface area product. Because of the loss of tracer from the tissue, the opposite occurs when the blood-to-tissue clearance of radioactive albumin is used.

Sulfate concentrations and transport in human bronchial epithelial cells

Inorganic sulfate concentrations in the cytoplasm of human bronchial epithelial cells exceeded levels in the bathing medium under all circumstances tested. Cell sulfate concentrations were directly related to medium sulfate concentrations and inversely related to medium chloride concentrations. In physiological media there was a sulfate compartment of approximately 0.3 mM that exchanged very slowly with extracellular sulfate. In media lacking chloride, sulfate was accumulated by the cells to a level as high as 2 mM. Sulfate uptake was markedly inhibited by external chloride and by stilbene sulfonic acid derivatives but was not affected by sodium in the medium. Efflux of 35SO4(2-) was stimulated by both chloride and sulfate in the bathing medium but inhibited by stilbenes. The following compounds had no effect on sulfate movements: phorbol esters, adenosine 3',5'-cyclic monophosphate derivatives, and okadaic acid. Changes in medium tonicity were likewise without effect. Our results suggest that human bronchial epithelial cells maintain a steady-state disequilibrium for inorganic sulfate. Furthermore, sulfate appears to exist in at least two compartments in the cells: one that is slowly exchangeable with sulfate in the medium and another exchangeable compartment that is of negligible size in physiological media but that becomes very large in media lacking chloride. Sulfate is transported by an anion exchanger of broad specificity that is not influenced by substances known to modulate chloride channels.

Eosinophils increase lung microvascular permeability via the peroxidase-hydrogen peroxide-halide system. Bronchoconstriction and vasoconstriction unaffected by eosinophil peroxidase inhibition

Eosinophils have been implicated as effector cells in producing vascular and bronchial constriction and increased microvascular permeability in the lung. Hypohalous acids produced by the eosinophil peroxidase (EPO)-hydrogen peroxide (H2O2)-halide system are stable cytotoxic oxidants. We measured the effects of EPO inhibition in activated eosinophils on vascular permeability, assessed using the capillary filtration coefficient (Kf,c), vascular resistance (Rt,vasc), and airway resistance (Raw) in isolated rat lungs perfused with 5% bovine albumin in Kreb's solution. Eosinophils were harvested by bronchoalveolar lavage of Toxicara canis-infected rats. Infusion of 2 x 10(6) phorbol myristate acetate (PMA)-activated cells produced a 3.3-fold increase in Rt,vasc at 30 min, primarily caused by small vessel constriction, a 2.5-fold increase in Raw at 150 min, and a 1.8-fold increase in Kf,c at 90 min. Inhibition of EPO using 3-amino-1,2,4-triazole (3-AT) prevented the increases in Kf,c, but not those in eosinophil superoxide production, Rt,vasc, or Raw. Addition of 2 mM sodium bromide as preferential EPO substrate caused Kf,c, but not Rt,vasc, or Raw, to increase significantly (2.5-fold) compared with activated eosinophils alone. Thus, the acute changes in microvascular permeability were modulated by activity of the EPO-H2O2-Halide system, but the increased vascular and bronchial resistances were mediated through a different pathway.

Capillary filtration coefficients using laser densitometry and gravimetry in isolated dog lungs

We compared pulmonary capillary filtration coefficients (Kf,c) using measurements of transcapillary filtration rates based on laser densitometry of perfusate hematocrit changes (Jy,l) and gravimetric measurement of the rate of lobe weight gain (delta Wt/delta t) after an increase in capillary pressure (Pc) in isolated autologous blood-perfused dog lungs. Although the lobe weight increased at a rate that decreased with time, the densitometric filtration rate was relatively constant over time. Kf,c values were calculated in milliliters per minute per centimeter water per 100 g from filtration rates obtained by 1) extrapolation of the delta Wt/delta t from 3 to 10 min back to time 0 [Kf,c(0)], 2) use of the slope of the line fitted to the delta Wt/delta t and Jv,l values obtained after three stepwise increases in Pc [Kf,c(slope)], and 3) use of delta Wt/delta t and Jv,l values obtained 10, 20, and 30 min after either a constant 30-min or three 10-min stepwise increases in Pc [Kf,c(t)]. The mean Kf,c(0) values ranged from 0.171 +/- 0.024 to 0.188 +/- 0.070 and were not significantly different between vascular pressure states. These Kf,c(0) values were significantly higher than all gravimetric or densitometric Kf,c(t) or Kf,c(slope) values that ranged from 0.037 to 0.100. Kf,c(t) values were not statistically different from each other by use of either method, but the gravimetric Kf,c(slope) was significantly higher than the densitometric value. Therefore, extrapolated Kf,c(0) probably overestimates endothelial barrier Kf,c because of persistent vascular stress relaxation after a vascular pressure increase. Adjustment of tissue Starling forces may occur rapidly after an increase in filtration pressure.

Total body studies in normal British women using dual energy X-ray absorptiometry

We report dual energy X-ray absorptiometry (DXA) studies of total body bone mineral and body composition performed in 111 normal caucasian women (aged 42-61). Conventional DXA scans of the lumbar spine and femoral neck were also obtained and each woman completed a detailed questionnaire. Significant correlations were found between total body BMD and BMD in the lumbar spine (r = 0.76) and femoral neck (r = 0.72). We present reference range data for BMD in the total body and in seven subregions of the skeleton. Multiple linear regressions of total body BMD and BMC on weight, height and age showed that the inclusion of height compared with weight and age alone was not statistically significant. The dependence of total body BMD on weight and age was: total body BMD (g cm-2) = 1.043 + 0.0042 x weight (kg) - 0.0039 x age (years) (R = 0.46, SEE = 0.074 g cm2). Body mass derived from DXA scans correlated well with weight measured on scales (r = 0.996, SEE = 0.77 kg). Body composition measurements agreed closely with % body fat estimated from skinfold measurements (r = 0.93), body fat mass estimated from a predictive equation based on weight, height and age (r = 0.91) and % body fat estimated from a predictive equation based on body mass index (r = 0.76). Study precision gave coefficients of variation of 0.6% for total body BMD and 0.7% for % body fat.

Mechanisms of ventilator-induced lung injury

OBJECTIVES

To describe the physiologic mechanisms of ventilator-induced lung injury and to define the major ventilator and host-dependent risk factors that contribute to such injury.

DATA SOURCE

Basic science and clinical studies related to ventilator-induced barotrauma and lung pathophysiology.

STUDY SELECTION

Emphasis on controlled, experimental studies and clinical studies related to specific mechanisms.

DATA EXTRACTION

Preference given to studies with quantitative end-points to assess damage and causal relationships.

DATA SYNTHESIS

Related studies are integrated to obtain basic mechanisms of damage where possible.

CONCLUSIONS

Ventilation with high tidal volumes can increase vascular filtration pressures; produce stress fractures of capillary endothelium, epithelium, and basement membrane; and cause lung rupture. Mechanical damage leads to leakage of fluid, protein, and blood into tissue and air spaces or leakage of air into tissue spaces. This process is followed by an inflammatory response and possibly a reduced defense against infection. Predisposing factors for lung injury are high peak inspiratory volumes and pressures, a high mean airway pressure, structural immaturity of lung and chest wall, surfactant insufficiency or inactivation, and preexisting lung disease. Damage can be minimized by preventing overdistention of functional lung units during therapeutic ventilation.

Psychological factors, immunologic activation, and disease activity in rheumatoid arthritis

The purpose of this study was to use structural equation modeling techniques to examine potential interrelationships among psychological factors, immunologic activation, and disease activity in rheumatoid arthritis (RA). The subjects were 80 male patients with a diagnosis of classic or definite RA. Measures included the Beck Depression Inventory, the Arthritis Helplessness Index, and the Arthritis Impact Measurement Scales (AIMS) pain score. Joint counts and immunophenotypic analyses of peripheral blood lymphocytes also were collected. Path analysis showed that percentage of HLA-DR+ cells in the peripheral blood and helplessness were related to join count. In addition, joint count had an effect upon depression. Depression had an effect upon pain, but there was no reciprocal effect of pain upon depression. This study describes a preliminary path model of interrelationships among psychological factors, immunologic activation, and disease activity in RA.

Primary cerebral lymphoma manifested by dementia

Primary cerebral lymphoma (PCL) accounts for less than 1% of intracranial neoplasms. In immunocompromised patients, multicentric lymphoma of the brain is typically manifested by focal neurologic deficits. In the immunocompetent individual, PCL involves leptomeninges and presents meningeal signs. Leptomeningeal lymphoma manifested by dementia has not been previously reported and should be included in the differential diagnosis of patients with Alzheimer's disease.