bluuebunny/crossref_metadata_2025 huggingface dataset:
Hes1 Regulates Corneal Development and the Function of Corneal Epithelial Stem/Progenitor Cells
Authors: Nakamura Takahiro , Ohtsuka Toshiyuki , Sekiyama Eiichi , Cooper Leanne J. , Kokubu Hiroshi , Fullwood Nigel J. , Barrandon Yann , Kageyama Ryoichiro , Kinoshita Shigeru
Published: February 2008

Hes1, a major target gene in Notch signaling, regulates the fate and differentiation of various cell types in many developmental systems. To gain a novel insight into the role of Hes1 in corneal tissue, we performed gain-of-function and loss-of-function studies. We show that corneal development was severely disturbed in Hes1-null mice. Hes1-null corneas manifested abnormal junctional specialization, cell differentiation, and less cell proliferation ability. Worthy of note, Hes1 is expressed mainly in the corneal epithelial stem/progenitor cells and is not detected in the differentiated corneal epithelial cells. Expression of Hes1 is closely linked with corneal epithelial stem/progenitor cell proliferation activity in vivo. Moreover, forced Hes1 expression inhibits the differentiation of corneal epithelial stem/progenitor cells and maintains these cells' undifferentiated state. Our data provide the first evidence that Hes1 regulates corneal development and the homeostatic function of corneal epithelial stem/progenitor cells.

Disclosure of potential conflicts of interest is found at the end of this article.
Efficient Differentiation of Functional Hepatocytes from Human Embryonic Stem Cells
Authors: Agarwal Sadhana , Holton Katherine L. , Lanza Robert
Published: February 2008

Differentiation of human embryonic stem cells (hESCs) to specific functional cell types can be achieved using methods that mimic in vivo embryonic developmental programs. Current protocols for generating hepatocytes from hESCs are hampered by inefficient differentiation procedures that lead to low yields and large cellular heterogeneity. We report here a robust and highly efficient process for the generation of high-purity (70%) hepatocyte cultures from hESCs that parallels sequential hepatic development in vivo. Highly enriched populations of definitive endoderm were generated from hESCs and then induced to differentiate along the hepatic lineage by the sequential addition of inducing factors implicated in physiological hepatogenesis. The differentiation process was largely uniform, with cell cultures progressively expressing increasing numbers of hepatic lineage markers, including GATA4, HNF4α, α-fetoprotein, CD26, albumin, α-1-antitrypsin, Cyp7A1, and Cyp3A4. The hepatocytes exhibited functional hepatic characteristics, such as glycogen storage, indocyanine green uptake and release, and albumin secretion. In a mouse model of acute liver injury, the hESC-derived definitive endoderm differentiated into hepatocytes and repopulated the damaged liver. The methodology described here represents a significant step toward the efficient generation of hepatocytes for use in regenerative medicine and drug discovery.

Disclosure of potential conflicts of interest is found at the end of this article.
Material Balance Revisited
Authors: Ojo K. P. , Osisanya S. O.
Published: February 2008

The material balance is a very important part of the reservoir engineer’s toolbox that is being relegated to the background in today’s reservoir evaluation workflow. This paper examines some issues that normally preclude its regular use especially as a pre-step before moving into full reservoir simulation and the use of a new method of analyzing the material balance equation called the dynamic material balance method for solving some of these issues.

The dynamic material balance method allows the simultaneous determination of the initial oil-in-place (N) or initial gas-in-place (G), ratio of initial gas to oil (m), reservoir permeability (K) or skin factor (S) and average pressure history of a reservoir from the combination of solution to the material balance equation and pressure transient analysis theory. Cumulative production history and PVT data of the reservoir are used with limited or no pressure data.

By introducing a time variable into the classical material balance equation (MBE) and combining the solutions of the resulting equations with the theory of pressure transient analysis, the cumulative production history of the reservoir and readily available PVT data of the reservoir fluids, we can estimate not only the original reserves in place, but also determine the average reservoir pressure decline history as indicated by the net fluid withdrawal from the reservoir. The reservoir permeability and skin factor as seen within the drainage area of each producing well can then be estimated from the already determined average pressure decline history.

This method is expected to improve the use of material balance by expanding the list of problems that can be tackled using material balance especially to reservoirs in marginal fields and reservoirs in which limited pressure data is available.
Economic Analysis of Innovative Approaches to Marginal Field Development
Authors: Yeghenee Nna Kue , Oyinkepreye David Orodu
Published: February 2008

This paper focus on economic analysis and evaluation on possible development concepts of a small offshore field with recoverable reserve of 45million bbl, situated in shallow water depth of about 100m, and remote from existing or scheduled installation thereby rendering it not feasible as a candidate for satellite development. Short listed concepts considered innovative were evaluated in other to choose the option that maximized NPV. They were scaled through other profitability criteria based on results obtained from using cash flow economic simulation tools. The analysis showed that not all non conventional approaches are suitable for marginal field development.

These concepts are considered innovative because they seek to integrate a combination of concepts anchored on proven technology while adapting it to produce fields that cannot be produced using conventional techniques because of their low marginal return. In the cause of this study, Jack–Up Production Platform on a Concrete Sub-sea Storage tank when used as a development concept had the greatest return on investment.In the future, the adoption of such systems will make possible the development of marginal fields discovered, but could not be developed due to their perceived low marginal return.
Nitrous Oxide Emissions from a Northern Great Plains Soil as Influenced by Nitrogen Management and Cropping Systems
Authors: Dusenbury M. P. , Engel R. E. , Miller P. R. , Lemke R. L. , Wallander R.
Published: February 2008

Field measurements of N2O emissions from soils are limited for cropping systems in the semiarid northern Great Plains (NGP). The objectives were to develop N2O emission‐time profiles for cropping systems in the semiarid NGP, define important periods of loss, determine the impact of best management practices on N2O losses, and estimate direct N fertilizer‐induced emissions (FIE). No‐till (NT) wheat (Triticum Aestivum L.)‐fallow, wheat‐wheat, and wheat‐pea (Pisum sativum), and conventional till (CT) wheat‐fallow, all with three N regimes (200 and 100 kg N ha−1 available N, unfertilized control); plus a perennial grass‐alfalfa (Medicago sativa L.) system were sampled over 2 yr using vented chambers. Cumulative 2‐yr N2O emissions were modest in contrast to reports from more humid regions. Greatest N2O flux activity occurred following urea‐N fertilization (10‐wk) and during freeze–thaw cycles. Together these periods comprised up to 84% of the 2‐yr total. Nitrification was probably the dominant process responsible for N2O emissions during the post‐N fertilization period, while denitrification was more important during freeze–thaw cycles. Cumulative 2‐yr N2O‐N losses from fertilized regimes were greater for wheat‐wheat (1.31 kg N ha−1) than wheat‐fallow (CT and NT) (0.48 kg N ha−1), and wheat‐pea (0.71 kg N ha−1) due to an additional N fertilization event. Cumulative losses from unfertilized cropping systems were not different from perennial grass‐alfalfa (0.28 kg N ha−1). Tillage did not affect N2O losses for the wheat‐fallow systems. Mean FIE level was equivalent to 0.26% of applied N, and considerably below the Intergovernmental Panel on Climate Change mean default value (1.25%).
The Impact of Agricultural Runoff on the Quality of Two Streams in Vegetable Farm Areas in Ghana
Authors: Ntow William J. , Drechsel Pay , Botwe Benjamin Osei , Kelderman Peter , Gijzen Huub J.
Published: February 2008

A study of two small streams at Akumadan and Tono, Ghana, was undertaken during the rain and dry season periods between February 2005 and January 2006 to investigate the impact of vegetable field runoff on their quality. In each stream we compared the concentration of current‐use pesticides in one site immediately upstream of a vegetable field with a second site immediately downstream. Only trace concentrations of endosulfan and chlorpyrifos were detected at both sites in both streams in the dry season. In the wet season, rain‐induced runoff transported pesticides into downstream stretches of the streams. Average peak levels in the streams themselves were 0.07 μg L−1 endosulfan, 0.02 μg L−1 chlorpyrifos (the Akumadan stream); 0.04 μg L−1 endosulfan, 0.02 μg L−1 chlorpyrifos (the Tono stream). Respective average pesticide levels associated with streambed sediment were 1.34 and 0.32 μg kg−1 (the Akumadan stream), and 0.92 and 0.84 μg kg−1 (the Tono stream). Further investigations are needed to establish the potential endosulfan and chlorpyrifos effects on aquatic invertebrate and fish in these streams. Meanwhile measures should be undertaken to reduce the input of these chemicals via runoff.
Managing Broiler Litter Application Rate and Grazing to Decrease Watershed Runoff Losses
Authors: Sistani K. R. , Brink G. E. , Oldham J. L.
Published: February 2008

Pasture management and broiler litter application rate are critical factors influencing the magnitude of nutrients being transported by runoff from fields. We investigated the impact of pasture management and broiler litter application rate on nutrient runoff from bermudagrass (Cynodon dactylon) pastures. The experiment was conducted on a Ruston fine sandy loam with a factorial arrangement on 21 large paddocks. Runoff water was collected from natural rainfall events from 2001 to 2003. Runoff water and soil samples were analyzed for nutrients and sediments. Runoff was generally greater (29%) from grazed than hayed pastures regardless of the litter application rate. There was greater inorganic N in the runoff from grazed paddocks when litter rate was based on N rather than P. The mean total P loss per runoff event for all treatments ranged from 7 to 45 g ha−1 and the grazed treatment with litter applied on N basis had the greatest total P loss. Total dissolved P was the dominant P fraction in the runoff, ranging from 85% to 93% of the total P. The soluble reactive P was greater for treatments with litter applied on N basis regardless of pasture management. Runoff total sediments were greater for N‐based litter application compared to those which received litter on P basis. Our results indicate that litter may be applied on N basis if the pasture is hayed and the soil P is low. In contrast, litter rates should be based on a P‐basis if pasture is grazed.
The Effect of Tropical Sorghum Conversion and Inbred Development on Genome Diversity as Revealed by High‐Resolution Genotyping
Authors: Klein Robert R. , Mullet John E. , Jordan David R. , Miller Frederick R. , Rooney William L. , Menz Monica A. , Franks Cleve D. , Klein Patricia E.
Published: February 2008

Graphical genotypes have been generated for a set of sorghum [Sorghum bicolor (L.) Moench] germplasm, which includes selected public inbreds, germplasm from the world collection, and ancestral lines central to the early breeding efforts of sorghum. We have focused our present examination on sorghum chromosome SBI‐06, which encodes ma1 and dw2, two genes critical to sorghum improvement dating to the original introduction of tropical sorghums into the United States. Utilizing the pedigree relationship between sorghum cultivars, the patterns of genetic variation were detailed within segmental chromosomal blocks of SBI‐06. Segmental genomic blocks were traced back through multiple generations of a pedigree, often back to founder tropical accessions. The graphical genotypes reveal genomic signatures of historical breeding decisions, especially evidence of directional selection during the conversion of tropical accessions to temperate adaptation. This information is central to our efforts to understand those crop improvement processes that have shaped the genomic diversity of elite sorghum cultivars.
Operation of the SHARON Denitrification Process to Treat Sludge Reject Water Using Hydrolyzed Primary Sludge to Denitrify
Authors: Dosta J. , Galí A. , El‐Hadj T. Benabdallah , Mata‐Álvarez J.
Published: February 2008

An efficient biological treatment to treat reject water from anaerobic digestion of wastewater sludge is the SHARON denitrification process, which takes place in a chemostat reactor, where aerobic/anoxic periods are alternated under specific hydraulic retention time (HRT) and temperature conditions that favor ammonium oxidizers growth and ensure the total washout of nitrite oxidizers, achieving the biological nitrogen removal over nitrite. An optimized performance of this process to treat Spanish reject water was obtained using methanol and working at an HRT of 2 days, 33°C, and cycle length of 2 hours. Supernatant of hydrolyzed primary sludge was tested to denitrify. Because biochemical oxygen demand was not extremely high in the primary sludge, the fluid dynamics of the system were changed, with respect to the strategy with methanol, but maintaining the reject water influent flowrate. The use of hydrolyzed primary sludge improved the process efficiency, because the alkalinity present in the primary sludge buffered the process until an optimum pH range.
Concentration and Recovery of Coliphages from Water with Bituminous Coal
Authors: Dafale Nishant , Lakhe Shrikumar , Yadav Krishnakant , Purohit Hemant , Chakrabarti Tapan
Published: February 2008

Coliphages represent a process indicator for fecal pollution. The coal bed concentration method prepared for enterovirus was refined for a concentration of coliphages. A bed made from 1.5 g of 120‐mesh coal powder was used for concentrating coliphage from 200 mL of a water sample with or without the addition of aluminum chloride at different pH values. The isolated E. coli strain EC‐R8 was found to be more susceptible to the desired coliphage and showed significant coliphage–coliform response, with clear plaque used for further studies. The complete coliphage adsorption was achieved with the addition of 0.0005 M AlCl3 at pH 6.0. Adsorbed coliphages were eluted with 3% beef extract in Mcllvaine buffer at pH 7.1, with an average recovery of 78.74%. This concentration technique was applied for the detection of coliphages from the well water of Nagpur city (India) and found to contain coliphages in the range of 2 to 28 plaque‐forming units per liter (PFU/L).
Investigation of Nitrification and Nitrogen Removal from Centrate in a Submerged Attached‐Growth Bioreactor
Authors: Pedros P. B. , Onnis‐Hayden A. , Tyler Charles
Published: February 2008

The purpose of this study was to investigate the nitrification and nitrogen removal from centrate produced in the dewatering process of anaerobically digested sludge, using a single‐unit, single‐zone submerged attached‐growth bioreactor. The nitrogen loading varied from 0.54 to 1.51 kg‐N/m3 · d. Stable ammonia oxidation (nitritification) to nitrite was demonstrated. A nitritification efficiency of 98% was achieved, while the denitrification efficiency varied from 84 to 99% (with methanol). The average total nitrogen removal was 85%. Inhibition of nitrite oxidation by a limited penetration of dissolved oxygen into the biofilm and free ammonia resulted in the accumulation of nitrite, while inhibition of ammonia oxidation by free nitrous acid did not occur. The quantity of biomass, in terms of volatile solids, ranged from 10 123 to 16 034 mg‐VS/L of media.
The Locus for Hypoglycemic Detection Shifts With the Rate of Fall in Glycemia
Authors: Saberi Maziyar , Bohland MaryAnn , Donovan Casey M.
Published: February 2008

OBJECTIVE—To ascertain whether portal glucose sensing extends beyond the portal vein to the superior mesenteric vein and then test whether the role of portal–superior mesenteric glucose sensors varies with the rate of fall in glycemia.

RESEARCH DESIGN AND METHODS—Chronically cannulated rats underwent afferent ablation of the portal vein (PV) or portal and superior mesenteric veins (PMV) or sham operation (control). One week later, animals underwent hyperinsulinemic-hypoglycemic clamps in which the hypoglycemic nadir, 2.48 ± 0.06 mmol/l, was reached at a rate of decline in glucose of −0.09 or −0.21 mmol · l−1 · min−1 (PMV and control only). Additional PMV and control animals received an intravenous injection of the glucopenic agent 2-deoxyglucose.

RESULTS—Inducing hypoglycemia slowly, at a rate of −0.09 mmol · l−1 · min−1, resulted in a 26-fold increase in epinephrine (23.39 ± 0.62 nmol/l) and 12-fold increase in norepinephrine (11.42 ± 0.92 nmol/l) for controls (P < 0.001). The epinephrine response to hypoglycemia was suppressed by 91% in PMV (2.09 ± 0.07 nmol/l) vs. 61% in PV (9.05 ± 1.59 nmol/l) (P < 0.001). The norepinephrine response to hypoglycemia was suppressed by 94 and 80% in PMV and PV, respectively, compared with that in controls. In contrast, when arterial glucose was lowered to 2.49 ± 0.06 mmol/l within 20 min, no significant differences were observed in the catecholamine responses for PMV and controls over the first 45 min of hypoglycemia (20–65 min). Only at min 105 were catecholamines significantly lower for PMV vs. controls. Injection of 2-deoxyglucose induced a very rapid sympathoadrenal response with no significant differences between PMV and controls.

CONCLUSIONS—The critical locus for hypoglycemic detection shifts away from the portal-mesenteric vein to some other loci (e.g., the brain) when hypoglycemia develops rapidly.
Association of IL-1ra and Adiponectin With C-Peptide and Remission in Patients With Type 1 Diabetes
Authors: Pfleger Christian , Mortensen Henrik B. , Hansen Lars , Herder Christian , Roep Bart O. , Hoey Hillary , Aanstoot Henk-Jan , Kocova Mirjana , Schloot Nanette C. ,   on behalf of the Hvidøre Study Group on Childhood Diabetes
Published: February 2008

OBJECTIVE—We investigated the association of anti-inflammatory cytokine interleukin (IL)-1 receptor antagonist (IL-1ra), adiponectin, proinflammatory cytokines IL-1β, IL-6, and CCL2, and tumor necrosis factor-α with β-cell function, metabolic status, and clinical remission in patients with recent-onset type 1 diabetes.

RESEARCH DESIGN AND METHODS—Serum was obtained from 256 newly diagnosed patients (122 males and 134 females, median age 9.6 years). Stimulated C-peptide, blood glucose, and A1C were determined in addition to circulating concentration of cytokines at 1, 6, and 12 months after diagnosis. Analyses were adjusted for sex, age, and BMI percentile.

RESULTS—Anti-inflammatory IL-1ra was positively associated with C-peptide after 6 (P = 0.0009) and 12 (P = 0.009) months. The beneficial association of IL-1ra on β-cell function was complemented by the negative association of IL-1β with C-peptide after 1 month (P = 0.009). In contrast, anti-inflammatory adiponectin was elevated in patients with poor metabolic control after 6 and 12 months (P < 0.05) and positively correlated with A1C after 1 month (P = 0.0004). Proinflammatory IL-6 was elevated in patients with good metabolic control after 1 month (P = 0.009) and showed a positive association with blood glucose disposal after 12 months (P = 0.047).

CONCLUSIONS—IL-1ra is associated with preserved β-cell capacity in type 1 diabetes. This novel finding indicates that administration of IL-1ra, successfully improving β-cell function in type 2 diabetes, may also be a new therapeutic approach in type 1 diabetes. The relation of adiponectin and IL-6 with remission and metabolic status transfers observations from in vitro and animal models into the human situation in vivo.
Ventromedial Hypothalamic Glucokinase Is an Important Mediator of the Counterregulatory Response to Insulin-Induced Hypoglycemia
Authors: Levin Barry E. , Becker Thomas C. , Eiki Jun-ichi , Zhang Bei B. , Dunn-Meynell Ambrose A.
Published: February 2008

OBJECTIVE—The counterregulatory response to insulin-induced hypoglycemia is mediated by the ventromedial hypothalamus (VMH), which contains specialized glucosensing neurons, many of which use glucokinase (GK) as the rate-limiting step in glucose's regulation of neuronal activity. Since conditions associated with increased VMH GK expression are associated with a blunted counterregulatory response, we tested the hypothesis that increasing VMH GK activity would similarly attenuate, while decreasing GK activity would enhance the counterregulatory response to insulin-induced hypoglycemia.

RESEARCH DESIGN AND METHODS—The counterregulatory response to insulin-induced hypoglycemia was evaluated in Sprague-Dawley rats after bilateral VMH injections of 1) a GK activator drug (compound A) to increase VMH GK activity, 2) low-dose alloxan (4 μg) to acutely inhibit GK activity, 3) high-dose alloxan (24 μg), or 4) an adenovirus expressing GK short hairpin RNA (shRNA) to chronically reduce GK expression and activity.

RESULTS—Compound A increased VMH GK activity sixfold in vitro and reduced the epinephrine, norepinephrine, and glucagon responses to insulin-induced hypoglycemia by 40–62% when injected into the VMH in vivo. On the other hand, acute and chronic reductions of VMH GK mRNA or activity had a lesser and more selective effect on increasing primarily the epinephrine response to insulin-induced hypoglycemia by 23–50%.

CONCLUSIONS—These studies suggest that VMH GK activity is an important regulator of the counterregulatory response to insulin-induced hypoglycemia and that a drug that specifically inhibited the rise in hypothalamic GK activity after insulin-induced hypoglycemia might improve the dampened counterregulatory response seen in tightly controlled diabetic subjects.
Persistence of Altered Movement Patterns During a Sit-to-Stand Task 1 Year Following Unilateral Total Knee Arthroplasty
Authors: Farquhar Sara J , Reisman Darcy S , Snyder-Mackler Lynn
Published: February 2008

Background and Purpose

Following total knee arthroplasty (TKA), quadriceps femoris muscle strength (force-generating capacity) and functional test scores improve but continue to be lower than those in people without injury. Analysis of the sit-to-stand (STS) task demonstrated side-to-side differences in subjects with TKA, as well as differences between subjects with TKA and control subjects. It was hypothesized that, when using a self-selected starting position, subjects 1 year following TKA would show improvements in strength and movement patterns but would continue to show asymmetries of angles and moments at the hips and knees.

Subjects and Methods

Twenty-four subjects (12 subjects with unilateral TKA and 12 control subjects) were recruited; those with TKA were tested 3 months and 1 year following surgery. Motion analysis of an STS task was synchronized with 2 force platforms and electromyography. Outcome measures included joint angles and moments, electromyography, vertical ground reaction forces, muscle strength, and functional performance tests.

Results

Subjects with TKA showed improvements in symmetry of motion, strength, and functional performance from 3 months to 1 year following TKA. Compared with control subjects, subjects with TKA relied on increased hip flexion and a larger hip extensor moment to perform the STS task.

Discussion and Conclusion

The increased hip extensor moment demonstrated that subjects adopted a strategy to avoid the use of the quadriceps femoris muscle, yet this strategy persisted as quadriceps femoris muscle strength improved. This pattern may be a learned movement pattern that may not resolve without retraining.
Usefulness of the Berg Balance Scale in Stroke Rehabilitation: A Systematic Review
Authors: Blum Lisa , Korner-Bitensky Nicol
Published: February 2008

Background

In a recent study of 655 physical therapists working with a stroke population, the Berg Balance Scale (BBS) was identified as the most commonly used assessment tool across the continuum of stroke rehabilitation. Given the widespread popularity of the BBS, it is important to critically appraise the BBS for its use with a stroke population.

Objective

The purposes of this study were to conduct a systematic review of the psychometric properties of the BBS specific to stroke and to identify strengths and weaknesses in its usefulness for stroke rehabilitation.

Results

Twenty-one studies examining the psychometric properties of the BBS with a stroke population were retrieved. Internal consistency was excellent (Cronbach alpha=.92–.98) as was interrater reliability (intraclass correlation coefficients [ICCs]=.95–.98), intrarater reliability (ICC=.97), and test-retest reliability (ICC=.98). Sixteen studies focused on validity and generally found excellent correlations with the Barthel Index, the Postural Assessment Scale for Stroke Patients, Functional Reach Test, the balance subscale of Fugl-Meyer Assessment, the Functional Independence Measure, the Rivermead Mobility Index (except for weight shift and step-up items), and gait speed. Berg Balance Scale scores predicted length of stay, discharge destination, motor ability at 180 days poststroke, and disability level at 90 days, but these scores were not predictive of falls. Eight studies focused on responsiveness; all reported moderate to excellent sensitivity. Three studies found floor or ceiling effects.

Discussion and Conclusion

The BBS is a psychometrically sound measure of balance impairment for use in poststroke assessment. Given the floor and ceiling effects, clinicians may want to use the BBS in conjunction with other balance measures.
The influence of exercise during growth on ultrasonographic parameters of the superficial digital flexor tendon of young Thoroughbred horses
Authors: MOFFAT P. A. , FIRTH E. C. , ROGERS C. W. , SMITH R. K. W. , BARNEVELD A. , GOODSHIP A. E. , KAWCAK C. E. , McILWRAITH C. W. , van WEEREN P. R.
Published: February 2008

Reasons for performing study: Conditioning by early training may influence the composition of certain musculoskeletal tissues, but very few data exist on its effect during growth on tendon structure and function.

Objectives: To investigate whether conditioning exercise in young foals would lead to any ultrasonographically detectable damage to the superficial digital flexor tendon or an increase in cross‐sectional area (CSA).

Methods: Thirty‐three Thoroughbred foals reared at pasture were allocated to 2 groups: control (PASTEX) allowed exercise freely at pasture; andCONDEX, also at pasture, began conditioning exercise from mean age 21 days over 1030 m on a purpose‐built oval grass track, for 5 days/week until mean age 18 months. Foals were observed daily, and underwent orthopaedic examination monthly. Ultrasonographic images of the superficial digital flexor tendon (SDFT) at the mid‐metacarpal level of both forelimbs were obtained in all foals at ages 5, 8, 12, 15 and 18 months. CSA was validated (r2= 0.89) by determining CSA from digital photographs of the transected SDFT surface from 12 of the horses necropsied at age 17.1 months.

Results: There was no clinical or ultrasonographic evidence of tendonopathy in either group and the greatest increase in mean CSA in both groups occurred between age 5 and 8 months. Across all age categories, there was no significant difference in mean CSA between the left and right limbs, or colts and fillies; there was a trend towards a larger CSA in theCONDEXgroup (P = 0.058).

Conclusions: There was no conclusive evidence for a structural adaptive hypertrophy of the SDFT, probably because the regimen was insufficiently rigorous or because spontaneous pasture exercise may induce maximal development of energy storing tendons.

Potential relevance: A moderate amount of early conditioning exercise against a background of constant exercise at pasture is not harmful to the development of the flexor tendons.
Ocular penetration of intravenously administered enrofloxacin in the horse
Authors: DIVERS T. J. , IRBY N. L. , MOHAMMED H. O. , SCHWARK W. S.
Published: February 2008

Reason for performing study: Information on antibiotic concentrations in the equine eye following systemic therapy is limited. Reports thatLeptospiraspp. are frequently present in the eyes of horses with recurrent uveitis, emphasises a need for studies on ocular concentrations of specific antibiotics.

Hypotheses: 1) Enrofloxacin, administered i.v. at 7.5 mg/kg bwt q. 24 h, results in aqueous humour concentrations greater than the reported minimum inhibitory concentration (MIC) forLeptospira pomona.2) Aqueous humour paracentesis sufficiently disrupts the blood‐aqueous humour barrier (BAB) to cause an increase in aqueous humour protein and enrofloxacin concentrations.

Methods: Aqueous humour enrofloxacin and total protein concentrations were determined in 6 healthy, mature horses after i.v. administration of enrofloxacin. Paracentesis was performed on the left eye on Days 3 and 4, one hour following enrofloxacin administration, to determine enrofloxacin concentrations in healthy eyes and in eyes with mechanical disruption of the BAB. Paracentesis was also performed on the right eye 23 h after enrofloxacin administration. Blood samples were collected from the horses at identical times to determine enrofloxacin aqueous humour:plasma ratios.

Results: Mean ± s.d. enrofloxacin concentration in the aqueous humour one hour post administration on Day 3 was 0.32 ± 0.10 mg/l (range 0.18‐0.47); and aqueous humour enrofloxacin, total protein and aqueous humour:plasma enrofloxacin ratios were higher on Day 4 than Day 3.

Conclusions and potential relevance: Following disruption of the BAB, enrofloxacin concentrations were above the reported MIC forLeptospira pomona.
Evaluation of a new strategy to modulate skeletal development in racehorses by imposing track‐based exercise during growth: The effects on 2‐ and 3‐year‐old racing careers
Authors: ROGERS C. W. , FIRTH E. C. , McILWRAITH C. W. , BARNEVELD A. , GOODSHIP A. E. , KAWCAK C. E. , SMITH R. K. W. , van WEEREN P. R.
Published: February 2008

Reasons for performing study: No data exist on the effects of conditioning exercise at foal age on workload and subsequent clinical injury rate during their 2‐ and 3‐year‐old racing careers.

Objectives: To investigate the effects of subjecting TB foals to conditioning exercise prior to the start of race training on: the workload required to reach a level of fitness sufficient to compete; and the prevalence of orthopaedic injury during the first 2 seasons of their racing careers.

Methods: Twenty 18‐month‐old TBs, 12 subjected to conditioning exercise at foal age (CONDEX) and 8 exercised spontaneously at pasture only (PASTEX) were trained and entered in competitive events. Workload was quantified using the cumulative workload index (the product of average velocity and distance at a specific gait) and the animals were monitored clinically and radiographically for signs of musculoskeletal disorders.

Results: Workload to reach the desired fitness level was similar for CONDEX and PASTEX. CONDEX performed more prerace training sessions as 2‐year‐olds (P<0.05). The incidence of orthopaedic injuries was low in both groups and there were no differences in the occurrence of orthopaedic ailments. PASTEX animals tended to show signs of musculoskeletal disorders earlier than CONDEX animals. This time difference was significant for metacarpophalangeal joint pain on flexion, reduced carpal flexion and hindlimb lameness (P<0.05).

Conclusions: Subjecting TB foals to conditioning exercise early in life does not have adverse effects on racing careers at ages 2 and 3 years, and does not influence the workload needed to reach a fitness level that is sufficient for racing.

Potential relevance: The lack of negative effects and the indications of some positive effects of early conditioning exercise in the Thoroughbred encourage further large‐scale comparative studies.
Effects of exercise on tenocyte cellularity and tenocyte nuclear morphology in immature and mature equine digital tendons
Authors: STANLEY R. L. , EDWARDS L. J. , GOODSHIP A. E. , FIRTH E. C. , PATTERSON‐KANE J. C.
Published: February 2008

Reasons for performing study: The injury‐prone, energy‐storing equine superficial digital flexor tendon (SDFT) of the mature performance horse has a limited ability to respond to exercise in contrast with the noninjury‐prone, anatomically opposing common digital extensor tendon (CDET). Previous studies have indicated low levels of cellular activity in the mature SDFT, but in foal tendons the tenocytes may still have the ability to adapt positively to increased exercise.

Objectives: To measure tenocyte densities and types in histological sections from the SDFT and CDET of horses from controlled long‐term, short‐term and foal exercise studies.

Methods: Specimens were collected from mid‐metacarpal segments of the CDET and SDFT for each horse and processed for histology; central and peripheral regions of the SDFT cross‐section were analysed separately (SDFTc, SDFTp). Tenocyte nuclei were counted in a total area of 1.59 mm2 for each tendon region in each horse. Each nucleus was classified as type 1 (elongate and thin), type 2 (ovoid and plump) or type 3 (chondrocyte‐like); type 1 cells are proposed to be less synthetically active than type 2 cells.

Results: No significant differences were noted between exercise and control groups in any of the studies, with the exception of an exercise‐related reduction in the proportion of type 1 tenocytes for all tendons combined in the long‐term study. There were tendon‐ and site‐specific differences in tenocyte densities and proportions of type 1 and 2 cells in all 3 studies.

Conclusions and potential relevance: There was no indication that exercise increased tenocyte density or proportions of the (theoretically) more active type 2 cells in immature horses (short‐term and foal studies), perhaps because the training regimens did not achieve certain threshold strain levels. In the foal study these findings can still be interpreted positively as evidence that the training regimen did not induce subclinical damage.
Monitoring the fate of autologous and allogeneic mesenchymal progenitor cells injected into the superficial digital flexor tendon of horses: Preliminary study
Authors: GUEST D. J. , SMITH M. R. W. , ALLEN W. R.
Published: February 2008

Autologous mesenchymal progenitor cells (MPCs) purified from bone marrow aspirates are being used in the treatment of superficial digital flexor tendon (SDFT) injuries in the horse with promising results. In this study the fate of autologous and allogeneic MPCs following injection into the SDFT was monitored by stable transfection of MPCs with green fluorescent protein (GFP). Small lesions were created manually in one forelimb SDFT of 2 horses and injected with autologous MPCs, allogeneic MPCs or bone marrow supernatant alone.Post mortemexaminations performed after 10 or 34 days revealed GFP labelled cells located mainly within injected lesions, but with a small proportion integrated into the crimp pattern of adjacent healthy areas of tendon. Furthermore, there was no visible cell mediated immune response to allogeneic MPCs in either of the host horses.
The efficacy of a commercial ELISA as an alternative to virus neutralisation test for the detection of antibodies to EAV
Authors: DUTHIE S. , MILLS H. , BURR P.
Published: February 2008

Infection with equine arteritis virus is a notifiable disease with sporadic occurrence in the UK. As stallions may harbour the virus after infection, horses are screened for exposure by serological testing prior to breeding. The virus neutralisation test is considered the ‘gold standard’ serological screening test, but it is time‐consuming and labour intensive; consequently there is a move towards more rapid screening methodology. In this study, a commercially available EVA antibody ELISA is assessed. The ELISA performed poorly with a sensitivity of 26% and a specificity of 96% in the samples analysed. It was concluded that this ELISA would be of little value for reducing sample turnaround time. The study emphasises the need for in‐house validation of commercially available kits.
Brain tumor stem cells: new targets for clinical treatments?
Authors: Tunici Patrizia , Irvin Dwain , Liu Gentao , Yuan Xiangpeng , Zhaohui Zeng , Ng Hiushan , Yu John S.
Published: February 2008

✓ The observation of similarities between the self-renewal mechanisms of stem cells and cancer cells has led to the new concept of the cancer stem cell. In cases of leukemia, multiple myeloma, and breast cancer, cells with a high self-renewal potential have been identified. Furthermore, investigators have shown these cells' ability to drive the formation and growth of the tumor. Brain tumors have also been reported to possess a subpopulation of cancer stemlike cells that have the ability to proliferate, self-renew, and be multipotent. When grafted into mice, these cells are also able to generate a tumor that recapitulates that of the patient from whom the cells were derived. The identification and characterization of this new category of cells call for new therapies capable of selectively targeting and killing these multifaceted cells.
Identification and Characterization of Oxylipid‐Protein and Peptide Conjugates by Mass Spectrometry
Authors: Chung Woon‐Gye , Maier Claudia S.
Published: February 2008

The modification of proteins by reactive products of lipid peroxidation is associated with a large number of diseases and biological aging; thus, methods that enable the characterization of oxylipid‐protein and/or peptide conjugates are highly in demand. This unit outlines a chemical labeling approach to identifying and characterizing proteins modified by lipid peroxidation products. It also outlines two approaches for mass spectrometry–based identification and detailed characterization of oxylipid conjugates. The first combines chemical labeling of oxylipid‐protein conjugates using an aldehyde‐specific biotinylation reagent, electrophoretic separation, and mass spectrometry–based identification of the biotinylated proteins. In the second approach, protein extracts are treated with the aldehyde‐specific reagent, proteolyzed using trypsin, and the biotinylated peptides are enriched using immobilized monomeric avidin. The enriched peptide fractions are submitted to tandem mass spectrometry for determining the peptide sequence information, site of the modification, and chemical nature of the oxylipid. Curr. Protoc. Toxicol. 35:17.9.1‐17.9.19. © 2008 by John Wiley & Sons, Inc.
Detection and Analysis of Protein‐Protein Interactions of Organellar and Prokaryotic Proteomes by Blue Native and Colorless Native Gel Electrophoresis
Authors: Krause Frank , Seelert Holger
Published: February 2008

Native gels enable the analysis of protein complexes on a proteome‐wide scale in a single experiment. The protocols described in this unit are based on separation of protein complexes by blue native polyacrylamide electrophoresis (BN‐PAGE), the most versatile native gel system, and the closely related milder colorless native PAGE (CN‐PAGE). Both BN‐PAGE and CN‐PAGE are described on analytical to preparative scales. In addition, methods for subsequent analysis of protein complexes are given, including electroelution from native gels as well as denaturing and native two‐dimensional PAGE. Finally, the removal of Coomassie dye from electroeluted proteins is detailed along with a discussion of fundamental considerations for the solubilization of membrane protein complexes from various biological samples, which are exemplified for mitochondria, chloroplasts (thylakoids), and cyanobacteria. Curr. Protoc. Protein Sci. 51:14.11.1‐14.11.36. © 2008 by John Wiley & Sons, Inc.
Characterization of Mouse Hematopoietic Stem and Progenitor Cells
Authors: Miller Cindy L. , Dykstra Brad , Eaves Connie J.
Published: February 2008

The unit describes functional assays for the quantification of mouse hematopoietic stem cells and progenitor cells. The competitive repopulating unit (CRU) assay detects transplantable mouse hematopoietic stem cells with the capacity to regenerate all of the blood cell lineages for extended time periods in vivo. The long‐term culture‐initiating cell (LTC‐IC) assay, founded on the bone marrow long‐term culture system, measures primitive hematopoietic progenitors based on their capacity to produce myeloid progeny for at least four weeks. Colony‐forming cell (CFC) assays, performed in semisolid medium cultures to assess mouse pre‐B, megakaryocyte, erythroid, granulocyte‐monocyte, and multipotential hematopoietic progenitors are also described. These assays are powerful tools for evaluating human stem cell (HSC) and progenitor content in various hematopoietic tissues, during development as well as in the adult animal, and in cell populations manipulated ex vivo. Curr. Protoc. Immunol. 80:22B.2.1‐22B.2.31. © 2008 by John Wiley & Sons, Inc.
Monoclonal Antibodies to Human Cell Surface Antigens
Authors: Beare Alice , Stockinger Hannes , Zola Heddy , Nicholson Ian
Published: February 2008

Many of the leukocyte cell surface molecules are known by “CD” numbers. In this Appendix, a short introduction describes the history and the use of CD nomenclature and provides a few key references to enable access to the wider literature. This is followed by a table that lists all human molecules with approved CD names, tabulating alternative names, key structural features, cellular expression, major known functions, and usefulness of the molecules or antibodies against them in research or clinical applications. Curr. Protoc. Immunol. 80:A.4A.1‐A.4A.73. © 2008 by John Wiley & Sons, Inc.
Amino Acids: Chemical Properties
Authors: Dwyer Donard S.
Published: February 2008

A complete understanding of protein folding, protein recognition, enzyme catalysis, and allosteric regulation will require intimate knowledge about the fundamental physico‐chemical properties of amino acids. This article will summarize the chemistry of the 20 naturally occurring amino acids with special emphasis on the relationship to protein folding and biologic activity. The major features of the amino acids are classified into three categories, which are as follows: 1) physico‐chemical properties, 2) biologic properties, and 3) electronic properties. Cross‐correlations among more than 34 different parameters revealed that these measures segregate into four main properties that are largely independent, as follows: 1) steric effects (polarizability), 2) hydrophilicity (H
p
index), 3) inductive effects, and 4) field effects. Advances in quantum chemistry, nuclear magnetic resonance (NMR) analysis, and theoretic physics encourage efforts to derive all‐electronic expressions for the fundamental properties of amino acids that will provide mechanistic insights into protein structure and function.
Antibiotics: Bacterial Resistance
Authors: Wright Gerard D
Published: February 2008

Microbes have evolved a myriad of mechanisms to overcome the toxic effects of antibiotics, which include the production of enzymes that modify or degrade antibiotics, complex membrane‐associated efflux systems that can pump antibiotics out of the cell, modification of antibiotic targets, and the production of immunity proteins. The biochemical logic of resistance is often intimately linked with the mode of action of the antibiotics. As a result, chemical biology approaches for understanding resistance not only have application in our understanding of this phenomenon, but also they can guide the generation and deployment of new antibiotics. In this review, a survey of the chemical strategies employed by bacteria to resist antibiotics is presented with an emphasis on the molecular mechanisms of resistance enzymes and proteins.
Cell Cycle: Regulation
Authors: McAndrew Christopher W. , Gastwirt Randy F. , Donoghue Daniel J.
Published: February 2008

Normal regulation of the cell cycle ensures the passage of genetic material without mutations and aberrations. Proper completion of each phase is critical to the initiation of the following phase, and the pathways that cell division occur in an ordered, sequential, and irreversible procession. The two major cell‐cycle events that are regulated tightly are DNA replication and cell division. Progression through each phase transition is regulated by extracellular signaling, transcription factors, cyclin‐dependent kinases (CDKs), and checkpoints, which prevent uncontrolled cell division. Cyclin/CDK complexes are the primary factors responsible for the timely order of cell‐cycle progression, which include entry into S phase, initiation of DNA replication, and mitotic entry. Each phase of the cell cycle and the different cyclin/CDK complexes, as well as other important factors that regulate cell‐cycle progression and checkpoints, will be discussed.
Unraveling Cell Division Mechanisms with Small‐Molecule Inhibitors
Authors: Lampson Michael A. , Kapoor Tarun M.
Published: February 2008

Cell division is the process by which a cell creates two genetically identical daughter cells. To maintain genomic integrity, a complex and highly regulated sequence of events ensures that the replicated chromosomes are partitioned equally between the daughter cells. For more than 50 years, strategies designed around small‐molecule inhibitors have played a critical role in advancing our understanding of this essential process. Here we introduce a series of questions in the biology of cell division and illustrate how small molecules have been used to design experiments to address these questions. Because of the highly dynamic nature of cell division, the temporal control over protein function that is possible with small molecules has been valuable particularly in dissecting biologic mechanisms.
Chaperones, Molecular
Authors: Ellis R. John
Published: February 2008

The generic tendency of proteins to aggregate into nonfunctional, and sometimes cytotoxic, structures poses a universal problem for all types of cells. This problem is exacerbated by the high total concentrations of macromolecules found within most intracellular compartments, but it is solved by the actions of certain proteins that function as molecular chaperones. Different chaperones act by distinct mechanisms on both the folding of polypeptide chains and their subsequent assembly into oligomeric structures. Many chaperones, but not all, are also stress (or heat shock) proteins because the need for a chaperone function increases under stress conditions that cause proteins to unfold.
Chlorophylls and Carotenoids, Chemistry of
Authors: Scheer Hugo
Published: February 2008

Chlorophylls and carotenoids are essential pigments of photosynthesis, in which they have complementary functions for capturing light and transducing it to biochemical energy and for protecting against its deleterious effects. Carotenoids are also present in most other organisms where they have, besides photoprotection, a variety of other functions. Typical structures of both types of pigments are reviewed in this article as well as their functions, chemical properties, spectroscopy, biosynthesis, and applications.