Acceptance of interferon-gamma release assay by a high-risk urban cohort.

BACKGROUND: QuantiFERON ® -TB Gold (QFT-G), an interferon-gamma release assay, is approved for the diagnosis of latent tuberculosis infection (LTBI). It is unknown if patients at high risk for LTBI will more readily accept LTBI treatment based on tuberculosis skin testing (TST) or QFT-G. METHODS: Prospectively enrolled participants were interviewed, were read an informational paragraph on QFT-G, completed a questionnaire and were tested with QFT-G. RESULTS: A total of 230 consecutive participants with a history of hepatitis C virus infection and active or past illicit drug use were enrolled and underwent QFT-G testing: 77% had recent TST, 82% were human immuno- deficiency virus co-infected, 87% had a history of injection drug use, and 52% a history of homelessness. Of the 230 participants, 148 (64%) stated a preference for TST compared to QFT-G. The majority would take treatment based on either test (68%). A minority of patients (20%) stated a willingness to take LTBI treatment based on TST alone. Black race was associated with a willingness to take treatment based on TST (OR 2.72, 95%CI 1.05-7.10). CONCLUSIONS: Patients at high risk for LTBI were found to prefer TST to QFT-G. Most would accept treatment based on either test, and a subset stated unwillingness to take treatment based on QFT-G results. Outreach and education should accompany QFT-G roll-out in high-risk urban populations.

Inexpensive, universal serial bus-powered and fully portable lab-on-a-chip-based capillary electrophoresis instrument.

Capillary electrophoresis is a cornerstone of lab-on-a-chip (LOC) implementations for medical diagnostics. However, the infrastructure needed to operate electrophoretic LOC implementations tends to be large and expensive, hindering the development of portable or low-cost systems. A custom-designed and highly integrated microelectronic chip for high-voltage generation switching and interfacing is recently developed. Here, the authors integrate the microelectronic chip with a microfluidic chip, a solid-state laser, filter, lens and several dollars worth of electronic components to form an inexpensive and portable platform, which is the size of a mobile telephone. This compact system has such reduced power requirements that the complete platform can be operated using a universal serial bus link to a computer. It is believed that this system represents a significant advancement in practical LOC implementations for point-of-care medical diagnostics.

Trabecular scaffolds created using micro CT guided fused deposition modeling.

Free form fabrication and high resolution imaging techniques enable the creation of biomimetic tissue engineering scaffolds. A 3D CAD model of canine trabecular bone was produced via micro CT and exported to a fused deposition modeler, to produce polybutylene terephthalate (PBT) trabeculated scaffolds and four other scaffold groups of varying pore structures. The five scaffold groups were divided into subgroups (n=6) and compression tested at two load rates (49 N/s and 294 N/s). Two groups were soaked in a 25 °C saline solution for 7 days before compression testing. Micro CT was used to compare porosity, connectivity density, and trabecular separation of each scaffold type to a canine trabecular bone sample. At 49 N/s the dry trabecular scaffolds had a compressive stiffness of 4.94±1.19 MPa, similar to the simple linear small pore scaffolds and significantly more stiff (p<0.05) than either of the complex interconnected pore scaffolds. At 294 N/s, the compressive stiffness values for all five groups roughly doubled. Soaking in saline had an insignificant effect on stiffness. The trabecular scaffolds matched bone samples in porosity; however, achieving physiologic connectivity density and trabecular separation will require further refining of scaffold processing.

Computed tomography assessment of lung volume changes after bronchial valve treatment.

The aim of the present study was to correlate clinical outcome measures following treatment with bronchial valves with regional lung volume. Computed tomography (CT) scan data from 57 subjects with severe emphysema were obtained from nine North American clinical trial sites. IBV(R) Valves (Spiration, Inc., Redmond, WA, USA) were placed to occlude segmental and subsegmental bronchi in right and left upper lobes using a flexible bronchoscope. Subjects completed a St George's Respiratory Questionnaire (SGRQ), pulmonary function test (PFT) and exercise capacity test. CT scans were analysed at baseline and at 1, 3 or 6 months after treatment to measure total and lobar lung density, volume and mass. Total lung volumes measured using CT were strongly correlated with PFT and did not change with treatment. However, the treated upper lobes significantly decreased in volume in 88% of the observations, by mean+/-sd 335+/-444 mL, or a decrease of 10.2% in the 6 month data. The untreated lobes had an 11.6% increase in volume. Changes in regional lung volume were associated with clinically meaningful improvements in SGRQ (-8.95+/-16.22), but not clinically meaningful PFT changes. The significant health status improvements reported by subjects following bilateral bronchial valve treatment are associated with regional lung volume changes and interlobar shift measured using computed tomography.

Sensate scaffolds can reliably detect joint loading.

Treatment of cartilage defects is essential to the prevention of osteoarthritis. Scaffold-based cartilage tissue engineering shows promise as a viable technique to treat focal defects. Added functionality can be achieved by incorporating strain gauges into scaffolds, thereby providing a real-time diagnostic measurement of joint loading. Strain-gauged scaffolds were placed into the medial femoral condyles of 14 adult canine knees and benchtop tested. Loads between 75 and 130 N were applied to the stifle joints at 30 degrees, 50 degrees, and 70 degrees of flexion. Strain-gauged scaffolds were able to reliably assess joint loading at all applied flexion angles and loads. Pressure sensitive films were used to determine joint surface pressures during loading and to assess the effect of scaffold placement on joint pressures. A comparison of peak pressures in control knees and joints with implanted scaffolds, as well as a comparison of pressures before and after scaffold placement, showed that strain-gauged scaffold implantation did not significantly alter joint pressures. Future studies could possibly use strain-gauged scaffolds to clinically establish normal joint loads and to determine loads that are damaging to both healthy and tissue-engineered cartilage. Strain-gauged scaffolds may significantly aid the development of a functional engineered cartilage tissue substitute as well as provide insight into the native environment of cartilage.

Bronchiolitis obliterans following lung transplantation: early detection using computed tomographic scanning.

BACKGROUND: Computed tomographic (CT) scanning may enable earlier diagnosis of chronic lung allograft dysfunction than forced expiratory volume in 1 second (FEV1). A study was undertaken to determine intra-observer and inter-observer agreement of composite and air trapping CT scores, to examine the association of FEV1 with the composite and air trapping CT score, and to relate the baseline composite CT score to changes in FEV1 and changes in the composite CT score over 1 year. METHODS: Lung function and baseline CT scans following transplantation and at subsequent annual follow ups were analysed in 38 lung transplant recipients. Scans were randomly scored by two observers for bronchiectasis, mucus plugging, airway wall thickening, consolidation, mosaic pattern, and air trapping, and re-scored after 1 month. CT scores were expressed on a scale of 0-100 and correlated with FEV1 as a percentage of the post-transplant baseline value. RESULTS: The mean (SD) interval between baseline and follow up CT scans was 11.2 (4.7) months. Inter-observer and intra-observer agreement was good for both the composite and air trapping CT scores. There was a significant association between FEV1 and the composite CT score, with each unit of worsening in the baseline composite CT score predicting a 1.55% and 1.37% worsening in FEV1 over the following year (p<0.0001) and a 1.25 and 1.12 unit worsening in the composite CT score (p<0.0001) for observers 1 and 2, respectively. CONCLUSION: These findings indicate a potential role for a composite CT scoring system in the early detection of bronchiolitis obliterans.

An instrumented scaffold can monitor loading in the knee joint.

No technique has been consistently successful in the repair of large focal defects in cartilage, particularly in older patients. Tissue-engineered cartilage grown on synthetic scaffolds with appropriate mechanical properties will provide an implant, which could be used to treat this problem. A means of monitoring loads and pressures acting on cartilage, at the defect site, will provide information needed to understand integration and survival of engineered tissues. It will also provide a means of evaluating rehabilitation protocols. A "sensate" scaffold with calibrated strain sensors attached to its surface, combined with a subminiature radio transmitter, was developed and utilized to measure loads and pressures during gait. In an animal study utilizing six dogs, peak loads of 120N and peak pressures of 11 MPa were measured during relaxed gait. Ingrowth into the scaffold characterized after 6 months in vivo indicated that it was well anchored and bone formation was continuing. Cartilage tissue formation was noted at the edges of the defect at the joint-scaffold interfaces. This suggested that native cartilage integration in future formulations of this scaffold configured with engineered cartilage will be a possibility.

Dehydroepiandrosterone sulfate and beta-cell function: enhanced glucose-induced insulin secretion and altered gene expression in rodent pancreatic beta-cells.

Administration of dehydroepiandrosterone (DHEA), or its sulfated form (DHEAS), controls hyperglycemia in diabetic rodents without directly altering insulin sensitivity. We show that DHEAS enhanced glucose-stimulated insulin secretion when administered in vivo to rats or in vitro to beta-cell lines, without changing cellular insulin content. Insulin secretion increased from 3 days of steroid exposure in vitro, suggesting that DHEAS did not directly activate the secretory processes. DHEAS selectively increased the beta-cell mRNA expression of acyl CoA synthetase-2 and peroxisomal acyl CoA oxidase in a time-dependent manner. Although DHEAS is a peroxisomal proliferator, it did not alter the mRNA expression of peroxisomal proliferator-activated receptor (PPAR) alpha or beta, or enhance the activity of transfected PPAR alpha, beta, or gamma in vitro. Thus, DHEAS directly affected the beta-cell to enhance glucose-stimulated insulin secretion and increased the mRNA expression of specific beta-cell mitochondrial and peroxisomal lipid metabolic enzymes. This effect of DHEAS on insulin secretion may contribute to the amelioration of hyperglycemia seen in various rodent models of diabetes.

Implementation of on-site screening sigmoidoscopy positively influences utilization by primary care providers.

BACKGROUND & AIMS: Sigmoidoscopy is an effective screening strategy for colorectal cancer that is not widely used by primary care providers. The aim of this study was to assess the impact of "academic detailing" in the form of an outreach educational seminar combined with implementation of on-site sigmoidoscopy services performed by university-based gastroenterologists on provider compliance. METHODS: A controlled trial was initiated at 9 urban neighborhood health centers, including 4 intervention and 5 comparison sites. Baseline data on provider attitudes and practice patterns were collected using a validated questionnaire. Outcome measures included a year 1 follow-up survey of provider attitudes and quarterly review of screening sigmoidoscopy referrals using appointment logs to assess utilization. RESULTS: Overall self-reported compliance rates for screening sigmoidoscopy increased by 36% (baseline, 24%; year 1, 60%) for the intervention group vs. only 7% (baseline, 19%; year 1, 26%) for the comparison group (P = 0. 001). When stratified by site, compliance rates increased at each intervention site (range, 7%-92%) but at only 2 control sites. Use of screening sigmoidoscopy was also significantly greater at the intervention sites (47% vs. 4%; P

Helicobacter pylori lipopolysaccharide binds to CD14 and stimulates release of interleukin-8, epithelial neutrophil-activating peptide 78, and monocyte chemotactic protein 1 by human monocytes.

Helicobacter pylori gastritis is characterized by leukocyte infiltration of the gastric mucosa. The aims of this study were to determine whether H. pylori-derived factors stimulate chemokine release from human monocytes and to ascertain whether H. pylori lipopolysaccharide (LPS) may be responsible for this effect. Human peripheral blood monocytes were exposed to an H. pylori water extract (HPE) or to purified H. pylori LPS. Levels of the chemokines interleukin-8 (IL-8), epithelial neutrophil-activating peptide 78 (ENA-78), and monocyte chemotactic protein 1 (MCP-1) were measured by enzyme-linked immunosorbent assay. The contribution of H. pylori LPS to monocyte activation was determined by using the LPS antagonist Rhodobacter sphaeroides lipid A (RSLA) and a blocking monoclonal antibody to CD14 (60bca). HPE increased monocyte secretion of IL-8, ENA-78, and MCP-1. Heat treatment of HPE did not reduce its ability to activate monocytes. Purified H. pylori LPS also stimulated monocyte chemokine production but was 1,000-fold less potent than Salmonella minnesota lipid A. RSLA blocked H. pylori LPS-induced monocyte IL-8 release in a dose-dependent fashion (maximal inhibition 82%, P < 0.001). RSLA also inhibited HPE-induced IL-8 release (by 93%, P < 0.001). The anti-CD14 monoclonal antibody 60bca substantially inhibited IL-8 release from HPE-stimulated monocytes (by 88%, P < 0.01), whereas the nonblocking anti-CD14 monoclonal antibody did not. These experiments with potent and specific LPS inhibitors indicate that the main monocyte-stimulating factor in HPE is LPS. H. pylori LPS, acting through CD14, stimulates human monocytes to release the neutrophil-activating chemokines IL-8 and ENA-78 and the monocyte-activating chemokine MCP-1. Despite its low relative potency, H. pylori LPS may play an important role in the pathogenesis of H. pylori gastritis.

Glucose-induced time-dependent potentiation and "run down" of insulin secretion in islets of young rats.

A "run down" phenomenon in isolated islets from young rats has been detected, in which the amount of insulin released in response to glucose decreases with time. This has been studied in conjunction with glucose-induced time-dependent potentiation (TDP) to see if the two are related. Islets, isolated from 7-day-old rats, exposed to 16.7 mM glucose for the first time after 30, 75 and 120 minutes of perifusion in Krebs-Ringer bicarbonate buffer (KRB) and 2.8 mM glucose, showed a progressive loss of responsiveness, and less insulin was released at the later times. This run down of the responses was prevented by successive challenges with 16.7 mM glucose and marked TDP was observed. The earlier the islets were exposed to glucose the more effectively was the run down prevented. Also, and perhaps causally related to the prevention of run down, the earlier the exposure to glucose the greater the TDP of a subsequent response. The results could possibly be explained in terms of a shift in metabolism in the isolated 7-day islets, with resultant diminution of the signals for the stimulation of insulin release and TDP. Early, and repeated exposure to high glucose would appear to minimize and delay the metabolic shift.

Glucose-induced oscillatory insulin secretion in perifused rat pancreatic islets and clonal beta-cells (HIT).

Normal insulin secretion is oscillatory in vivo and from groups of perifused islets. Stimulation of rat islets with different glucose concentrations gave insulin oscillations of similar period (5-8 min) but increasing amplitude. It has been assumed that oscillatory secretion is due to oscillations in intracellular free Ca2+, as seen in single islets and single pancreatic beta-cells. However, when islets were perifused with diazoxide and high KCl to maintain high intracellular free Ca2+, insulin oscillations of similar amplitude and period still occurred on glucose stimulation, although superimposed on elevated basal secretion. Several likely possibilities for a diffusible synchronizing factor were tested, including pyruvate, lactate, ATP, and insulin itself; nevertheless, perifusion with high concentrations of these did not prevent insulin oscillations. Clonal pancreatic beta-cells (HIT) and dissociated islets also exhibited oscillatory insulin secretion, but with the 5- to 8-min period oscillations superimposed on 15- to 20-min period oscillations. These results indicate that the mechanisms for generating and synchronizing insulin oscillations reside in the beta-cell, although the structure of the islet may modulate the oscillation pattern.

A critical period in the development of the insulin secretory response to glucose in fetal rat pancreas.

Insulin secretion by fetal rat pancreas was studied at 19.5 and 20.5 days of gestation. Over this 24-hour period, the response to glucose changed rapidly from one that is insensitive to the calcium channel antagonist nitrendipine but markedly enhanced by the presence of the inhibitor of fatty acid oxidation 2-bromostearate, to one that is larger, sensitive to nitrendipine but now not enhanced by 2-bromostearate. The 19.5-day pancreas that is not affected by nitrendipine when responding to glucose alone, is inhibited by nitrendipine when the response to glucose is enhanced by 2-bromostearate. The data suggest a possible metabolic change in the developing B-cell in which fatty acid oxidation is decreased, glucose oxidation increased, and a change in stimulus-secretion coupling from a (KATP) channel-independent mechanism alone, to a combination of that system with the (KATP) channel-dependent system. This could be achieved by a simple increase in the strength of the signal from glucose metabolism.

Galanin-stimulated high-affinity GTPase activity in plasma membranes from RINm5F cells.

GTPase activity was studied in plasma membranes purified from the clonal beta-cell line RINm5F. GTPase activities were identified as two broad classes with high or low affinity for GTP. The low-affinity GTPase activity had a Km > 60 microM. In contrast, the high-affinity activity had a Km of 225 nM. Only the high-affinity activity was stimulated by galanin. The stimulated activity had a higher Km (448 nM) and Vmax (75 pmol P(i).min-1.mg-1 protein) compared with the basal. This does not necessarily reflect a complex mechanism of stimulation. Rather, it may reflect that basal activity most likely results from multiple GTPases, whereas the stimulated activity probably reflects one or two specific GTPases. Galanin stimulated the high-affinity GTPase, over the concentration range in which it inhibits stimulated insulin secretion, to a maximal rate 80% greater than the basal rate. The EC50 was 5 nM. Murine and porcine galanin had similar potencies and intrinsic activities on the GTPase. Treatment of the RINm5F cells with PTX before making membranes completely eliminated the stimulatory effect of galanin. Thus, galanin stimulates PTX-sensitive GTPase activity in RINm5F cell membranes in a manner consistent with receptor activation.

Glucose-induced insulin release in islets of young rats: time-dependent potentiation and effects of 2-bromostearate.

The development of glucose-stimulated insulin release and time-dependent potentiation (TDP) has been studied in isolated islets from 7-, 14-, and 21-day-old and 3-mo-old rats. Responses were small at 7 days and changed little at 14 days. At 21 days the amount of insulin released in response to glucose was two times that at 14 days but was still less than one-half that released by 3-mo islets. Glucose-induced TDP was absent at 7 days but was present at 21 days. The second phase response to glucose decreased with perifusion time in 7-, 14-, and 21-day islets. In 7- and 21-day islets, high glucose in the presence of 2-bromostearate, an inhibitor of fatty acid oxidation, prevented the time-dependent decrease in responses; in addition, it induced TDP and enhanced TDP in the 7-day and 21-day islets, respectively. The data suggest that, in the young islet, glucose metabolism fails to inhibit fatty acid oxidation as it does in the mature islet and that this leads to a diminished signal for stimulus-secretion coupling.

Geriatric constipation: brief update on a common problem.

Constipation occurs frequently in the elderly and is often multifactorial in origin. A search for an underlying cause is necessary, and can often be found by taking an adequate history and performing a thorough physical examination. A minority of patients require further investigation, guided by the clinical setting. Management should be directed at correcting the underlying cause and providing dietary advice and, less commonly, medication to allow restoration of a normal bowel habit.

Maternal diet and insulin secretion in islets of lactating, nonlactating, and young rats.

The effects of dietary phosphorus (P) on insulin secretion by pancreatic islets of rats at peak lactation (14 days after parturition) and by islets of nonlactating previously pregnant rats have been determined. In addition, the effects of changed dietary P in the maternal diet on insulin secretion by islets of the 1- and 14-day-old offspring were studied. Lactating rats had increased food intake relative to nonlactating rats and correspondingly increased P intake on the 0.4 and 0.7% P diets. Serum P levels were elevated in lactating rats consuming the 0.7% P feed relative to those on the 0.4% P feed and also relative to the nonlactating rats on the 0.7% P feed. Lactating rats had decreased bone calcium compared with the nonlactating rats. Islets from lactating rats on the 0.7% P feed secreted more insulin in response to glucose or to 3-isobutyl-1-methylxanthine (IBMX) than lactating rats on the 0.4% P feed. Additionally, lactating rats on the 0.7% P feed secreted more insulin in response to glucose than nonlactating rats on the same 0.7% P feed. The maternal diet had no influence on the endocrine pancreatic responses of the 1- and 14-day-old offspring in response to glucose or IBMX.

Galanin can inhibit insulin release by a mechanism other than membrane hyperpolarization or inhibition of adenylate cyclase.

Studies on the mode of action of galanin to inhibit insulin release in RINm5F cells have shown that basal and glyceraldehyde-stimulated release were both inhibited. Galanin was inhibitory at concentrations in the low nanomolar range. Binding studies with 125I-labeled galanin indicated that the RINm5F cells exhibit a single set of sites estimated to be of the order of 30,000 sites/cell. Displacement of 125I-galanin by galanin from the receptor sites occurred over a similar concentration range to that which inhibited insulin release. Half-displacement was achieved with 2 nM galanin. Measurements of bis-(1,3-diethylthiobarbiturate) trimethineoxonol (bis-oxonol) fluorescence showed that galanin hyperpolarized the RINm5F cell plasma membrane. Measurements of intracellular free calcium, [Ca2+]i by means of the fluorescent indicator fura-2 showed that galanin decreased [Ca2+]i. As galanin did not inhibit either basal or glyceraldehyde-stimulated insulin release in the presence of the Ca2+ channel blocker nitrendipine, the hyperpolarization and reduction of Ca2+ entry appear to be a possible explanation for the galanin effects. However, quantitatively, the effects on membrane potential and [Ca2+]i appear to be insufficient to account for the potent inhibition of insulin release. Furthermore, evidence for an additional mechanism of action was obtained from experiments with 12-O-tetradecanoylphorbol-13-acetate (TPA), a phorbol ester which stimulates insulin secretion by at least two mechanisms, one Ca2+ dependent and one Ca2+ independent. TPA-stimulated insulin release was inhibited by galanin over the same concentration range as for the inhibition of glyceraldehyde-stimulated release. Galanin inhibited TPA-stimulated release in the presence of maximally effective concentrations of nitrendipine and in the absence of extracellular Ca2+. These effects cannot be explained by hyperpolarization of the plasma membrane and consequent reduction of Ca2+ entry via the voltage-dependent Ca2+ channels. One suggested mechanism for the action of galanin is inhibition of adenylate cyclase. However, it was found that galanin inhibits insulin release even in the presence of 8-Br-cAMP, an agent which effectively bypasses adenylate cyclase. Therefore, an additional mechanism for the inhibitory effect of galanin must be present. All of the effects of galanin were sensitive to pertussis toxin. These data suggest two G-protein-dependent actions of galanin, one to hyperpolarize the plasma membrane and one at a distal point in stimulus-secretion coupling, close to the exocytotic event.

Significance of occult gastrointestinal bleeding during anticoagulation therapy.

A prospective study was undertaken to determine the effect of anticoagulation therapy on the prevalence of occult gastrointestinal bleeding and to ascertain the causes of bleeding. During a six-month period, 256 patients who had received anticoagulants were screened for occult bleeding with guaiac-impregnated cards. Twenty-one (12 percent) of the 175 patients who had received anticoagulants and who voluntarily completed the cards had occult gastrointestinal bleeding compared with only two (3 percent) of 74 control patients who had not received anticoagulants. The mean prothrombin time and partial thromboplastin time did not differ significantly in the patients who had received anticoagulants with and without subsequent bleeding. Fifteen of 16 patients who had received anticoagulants and who underwent diagnostic evaluation had previously undiagnosed lesions in the intestinal tract. These results indicate that occult gastrointestinal bleeding in a patient who has received an anticoagulant should not be attributed to the anticoagulant; instead, such bleeding often indicates the presence of significant intestinal disease.