Pharmacological characterization of a small-molecule agonist for the chemokine receptor CXCR3.

BACKGROUND AND PURPOSE: The chemokine receptor CXCR3 is a GPCR found predominantly on activated T cells. CXCR3 is activated by three endogenous peptides; CXCL9, CXCL10 and CXCL11. Recently, a small-molecule agonist, VUF10661, has been reported in the literature and synthesized in our laboratory. The aim of the present study was to provide a detailed pharmacological characterization of VUF10661 by comparing its effects with those of CXCL11. EXPERIMENTAL APPROACH: Agonistic properties of VUF10661 were assessed in a chemotaxis assay with murine L1.2 cells transiently transfected with cDNA encoding the human CXCR3 receptor and in binding studies, with [(125)I]-CXCL10 and [(125)I]-CXCL11, on membrane preparations from HEK293 cells stably expressing CXCR3. [(35)S]-GTPγS binding was used to determine its potency to induce CXCR3-mediated G protein activation and BRET-based assays to investigate its effects on intracellular cAMP levels and ß-arrestin recruitment. KEY RESULTS: VUF10661 acted as a partial agonist in CXCR3-mediated chemotaxis, bound to CXCR3 in an allosteric fashion in ligand binding assays and activated G(i) proteins with the same efficacy as CXCL11 in the [(35)S]-GTPγS binding and cAMP assay, while it recruited more ß-arrestin1 and ß-arrestin2 to CXCR3 receptors than the chemokine. CONCLUSIONS AND IMPLICATIONS: VUF10661, like CXCL11, activates both G protein-dependent and -independent signalling via the CXCR3 receptor, but probably exerts its effects from an allosteric binding site that is different from that for CXCL11. It could stabilize different receptor and/or ß-arrestin conformations leading to differences in functional output. Such ligand-biased signalling might offer interesting options for the therapeutic use of CXCR3 agonists.

Pharmacological modulation of chemokine receptor function.

G protein-coupled chemokine receptors and their peptidergic ligands are interesting therapeutic targets due to their involvement in various immune-related diseases, including rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, chronic obstructive pulmonary disease, HIV-1 infection and cancer. To tackle these diseases, a lot of effort has been focused on discovery and development of small-molecule chemokine receptor antagonists. This has been rewarded by the market approval of two novel chemokine receptor inhibitors, AMD3100 (CXCR4) and Maraviroc (CCR5) for stem cell mobilization and treatment of HIV-1 infection respectively. The recent GPCR crystal structures together with mutagenesis and pharmacological studies have aided in understanding how small-molecule ligands interact with chemokine receptors. Many of these ligands display behaviour deviating from simple competition and do not interact with the chemokine binding site, providing evidence for an allosteric mode of action. This review aims to give an overview of the evidence supporting modulation of this intriguing receptor family by a range of ligands, including small molecules, peptides and antibodies. Moreover, the computer-assisted modelling of chemokine receptor-ligand interactions is discussed in view of GPCR crystal structures. Finally, the implications of concepts such as functional selectivity and chemokine receptor dimerization are considered.

C(X)CR in silico: Computer-aided prediction of chemokine receptor-ligand interactions.

This review will focus on the construction, refinement, and validation of chemokine receptor models for the purpose of structure-based virtual screening and ligand design. The review will present a comparative analysis of ligand binding pockets in chemokine receptors, including a review of the recently released CXCR4 X-ray structures, and their implication on chemokine receptor (homology) modeling. The recommended protein-ligand modeling procedure as well as the use of experimental anchors to steer the modeling procedure is discussed and an overview of several successful structure-based ligand discovery and design studies is provided. This review shows that receptor models, despite structural inaccuracies, can be efficiently used to find novel ligands for chemokine receptors.:

A comparison of long-term outcome in first-episode schizophrenia following treatment with risperidone or a typical antipsychotic.

BACKGROUND: Most reports assessing the efficacy and tolerability of risperidone have involved patients previously treated with typical antipsychotics. Such patients are more likely to have a greater resistance or intolerance to treatment, thus restricting our interpretation of the impact a new treatment might have on the course of schizophrenia and possibly biasing the results. The present study examines the relative effectiveness of risperidone and typical antipsychotics in patients being treated for their first episode of schizophrenia. METHOD: From a cohort of 126 patients, 2 groups of 19 first-episode DSM-III-R/DSM-IV schizophrenia patients matched for age, gender, length of illness, and length of treatment and treated with either a typical antipsychotic or risperidone for a minimum of 1 year were compared on a number of outcome dimensions during their course of treatment and at follow-up. Treatment allocation was not random, and patients were judged to be compliant with medication. Patients treated with typical antipsychotics were followed up for a statistically nonsignificantly longer time (mean = 2.7 vs. 1.9 years). RESULTS: Six patients (31.6%) from the typical antipsychotic group were admitted to the hospital within the first year following the index admission compared with 1 patient (5.3%) in the risperidone group (admitted at month 14). Patients in the risperidone group showed a statistically significantly lower length of first hospitalization (p < .01), utilization of inpatient beds during the course of treatment (p < .001), and use of anticholinergic medication (p < .05). There were no statistically significant differences in symptom levels, either during the course of treatment or at follow-up; in the use of antidepressant, antianxiety, or mood-stabilizing drugs; or in changes in living circumstances or employment. CONCLUSION: These findings confirm at least equal long-term efficacy of typical antipsychotics and risperidone, but a possible advantage for risperidone in decreased service utilization and decreased use of anticholinergic drugs.

Concomitant blunt enteric injuries with injuries of the liver and spleen: a dilemma for trauma surgeons.

Prompt identification of enteric injuries after blunt trauma remains problematic. With the increased utilization of nonoperative management of blunt abdominal trauma gastrointestinal disruptions may escape timely detection and repair. The purpose of this study was to evaluate blunt enteric injuries requiring operative repair in adult patients and the association of concomitant hepatic and/or splenic injuries. Over a 10-year period (January 1990 through December 1999) 1648 patients suffered blunt liver, spleen, and/or enteric injuries, with 87 (5.3%) of these requiring operative repairs of the enteric injury. These patients had enteric injury only (EI) (60.9%; 53 of 87), concomitant enteric/splenic injury (ESI) (10.3%; 9 of 87), concomitant enteric/hepatic injury (EHI) (13.8%; 12 of 87), and enteric/hepatic/splenic injury (EHSI) 14.9% (13 of 87). A delay in treatment of >8 hours from presentation of EI compared with either EHI or ESI was not significantly different between the two groups. EHSI had exploratory laparotomy more expeditiously related to hemodynamic instability. Mortality rates were higher with EHI related to hemorrhagic shock and/or severe traumatic brain injury. Morbidity was not related to a delay in diagnosis until the period of delay was greater than 24 hours. The nonoperative management of blunt solid organ injury does not delay the detection and treatment of concomitant bowel injuries compared with isolated blunt enteric injuries. Occult enteric injury with solid organ injury has a low incidence and represents a continuing challenge to the clinical acumen of the trauma surgeon.

Prospective study of blunt aortic injury: Multicenter Trial of the American Association for the Surgery of Trauma.

BACKGROUND: Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years. METHODS: This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma. RESULTS: There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia. CONCLUSIONS: Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.

Failure of antiseptic bonding to prevent central venous catheter-related infection and sepsis.

Infection associated with the use of triple lumen catheters in hospitals is a frequent and serious complication. The prevailing hypothesis for the origin of catheter-related infection (CRI) is bacterial colonization and subsequent infection of the skin insertion site and catheter interface. The recently released ARROWgard catheter contains a bonded synergistic combination of silver sulfadiazine and chlorhexidine, which is thought to render the catheter resistant to bacterial colonization and subsequent sepsis. The purpose of this study is to compare the incidence of CRI and catheter-related sepsis (CRS) between a standard triple lumen catheter and ARROWgard antiseptic coated catheter in patients receiving total parenteral nutrition (TPN). A randomized, prospective clinical trial was conducted at a community referral center from January 1993 through April 1994. One-hundred-ninety-one patients with need for TPN were randomized to receive either the ARROWgard or a standard triple lumen catheter placed under a strict sterile protocol. CRI was defined as >/= 15 colony forming units by semiquantitative culture technique of the catheter tip or intracutaneous segment. CRS was defined as growth of the same organism on the catheter and at least one peripheral blood culture. All catheters were cultured. Ninety-two patients received the ARROWgard catheter, and 99 patients received the standard catheter. There were no differences between the average age, sex, length of hospital stay, days on TPN, number of catheters/patient, indications for TPN, primary diagnoses, or duration of the central line between the two groups. The overall rate of CRI was 11.5 per cent, and CRS was 8.4 per cent in this study. The rate of CRI for the ARROWgard was 10.9 per cent, compared with 12.9 per cent for the standard catheter (P = NS). The rate of CRS for the ARROWgard was 8.7 per cent, compared with 8.1 per cent for the standard catheter (P = NS). The coating of central venous catheters with silver sulfadiazine and chlorhexidine does not reduce the rate CRI or CRS when compared with standard central venous catheters in patients receiving TPN.

Failure of methylprednisolone to improve the outcome of spinal cord injuries.

The infusion of methylprednisolone (MP) within 8 hours of injury for spinal cord injuries (SCI) has been advocated to improve the motor function of patients after this catastrophic injury. However, clinical improvement in the outcome of SCI has not been consistently identified, despite the use of MP. We reviewed the outcome of SCI patients with MP to those without MP (No-MP) at two Level I Trauma Centers from 1989-1992. Acute SCI patients were identified from the trauma registries with trauma demographics and hospital data obtained from registry and medical records. Rehabilitation data for Functional Independence Measure (FIM) was obtained from the rehabilitation institute database. Primary outcome parameters were mortality, and for survivors, patient mobility (6 point scale) and FIM scores. There were 145 acute SCI patients: 80 treated with MP and 65 with No-MP. FIM data was available on 45 MP and 25 No-MP patients. There was no difference in the admission trauma score, ICU length of stay (LOS), or hospital LOS between the two groups. The MP patients were significantly younger (30 years vs 38 years, P = < 0.05) and had lower ISS scores (24 vs 31, P = < 0.05). There was no statistically significant difference in mortality (MP, 3.8% vs No-MP, 10.7%) between the two groups. Although admission mobility was not statistically different (MP, 5.99 vs No-MP, 5.90), there was a significantly poorer discharge mobility in the MP group when compared to the No-MP group (MP, 5.16 vs No-MP, 4.67, P = < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The continuing clinical dilemma of primary tumors of the small intestine.

Small intestinal tumors are relatively rare, notoriously difficult to diagnose, and often advanced at the time of definitive treatment. The purpose of this study is to compare the differences between benign and malignant tumors of the small intestine and between symptomatic and asymptomatic tumors with respect to their clinical presentation, efficacy of diagnostic procedures, and surgical management with correlation to pathologic findings. Forty-nine patients with primary small intestinal tumors between 1981-1993 had 17 benign and 32 malignant tumors. Benign tumors more commonly presented with acute gastrointestinal hemorrhage (29% versus 6%, P < 0.05), and were often asymptomatic (47% versus 6%, P < 0.05). Malignant tumors more commonly presented with abdominal pain (63% versus 24%, P < 0.05) and weight loss (38% versus 0%, P < 0.05). The total number of diagnostic tests/patient averaged 2.3 +/- 0.3, and the average time from onset of symptoms to resection was 30.2 +/- 6.6 weeks. Upper endoscopy, angiography, and upper gastrointestinal contrast studies had the most useful sensitivity rates. Surgical treatment of tumors included biopsy/excision, limited bowel resection, segmental resection with regional lymphadenectomy, or a bypass procedure. The most common types of benign and malignant tumors were leiomyoma (41%) and adenocarcinoma (53%), respectively. Histologically, tumors were evenly distributed throughout the small intestine. Small intestinal tumors remain difficult to diagnose because of an atypical presentation and renew the need for appropriate suspicion when treating patients with vague abdominal symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Experience with surgical resident training in a combined program in plastic surgery.

Healthcare reform may impact graduate medical education (GME) to reduce both specialty training positions and the length of training in these programs. General Surgery residencies often provide prerequisite training for surgery specialty training and will be affected by these changes. The purpose of this study is to identify the quality, outcome, and differences between PGYI-PGYIII categorical general surgery residents (GS) and matched prerequisite plastic surgery residents (PS). Concurrent comparisons analyzed American Board of Surgery Inservice Training Examinations (ABSITE) data from 1980-1992 as well as the surgery operative logs (SOL) and the curriculum of matched residents from 1989-1992. Outcome was assessed by board performance and from a piloted questionnaire to all PS graduates of the combined (3-year GS and 2-year PS) program. ABSITE analysis demonstrated satisfactory performance for both PS and GS at each PGY level, with significant increases each year for GS, but only between PGYI and PGYII for PS; there was a significant difference between PS and GS at all PGY levels. SOL analysis paralleled the curriculum and demonstrated more plastic surgery for PS compared to GS, with no difference in general surgery or hand surgery. PS program graduate respondents (32/44-72.7%) identified that the GS training/PS training was appropriate (71.9%/93.8%), effective (90.7%/93.8%) and of appropriate duration (87.5%/75.1%). 87.5 per cent of PS graduates completed ABPS certification. Combined PS training in all PS programs would reduce GME payments by over $20 million. Combined PS training is effective, appropriate, resource-efficient, and has an excellent outcome, but it requires a specific curriculum and close coordination between General Surgery and Plastic Surgery programs.

Assuring trauma system quality by outcomes reporting in two voluntary regional trauma networks.

1. Providing optimal trauma care for large populations requires the collaboration and cooperation of hospitals providing all levels of care. 2. Those who are seriously injured or who have complex injuries requiring special resources are to be referred in a timely fashion to a trauma center capable of providing optimal care. 3. In two regional trauma networks, 24% of injured patients were referred to a trauma center for definitive care. Overall survival was excellent.

Hospitalization and injury influence on the prosecution of drunk drivers.

The influence that injury and hospitalization from alcohol-related motor vehicle crashes may have on subsequent prosecution for drunk driving was studied utilizing concurrent controls consisting of three cohorts of drivers. The cohorts were drunk and injured drivers, drunk and not injured drivers, and sober and injured drivers. Even though the majority of intoxicated drivers were identified by police as having been drinking, evidentiary testing was not uniform. Culpability for the crash was high in the drunk cohorts compared with the sober drivers, and yet there was a statistically significant difference in the conviction rate of injured drunk drivers (59%) compared with uninjured drunk drivers (100%). Injury and hospitalization for drunk drivers after motor vehicle crashes affords protection from prosecution, and may enable ongoing risk-taking behavior by the drunk driver.

Multi-institutional survey of laparoscopic cholecystectomy.

Laparoscopic cholecystectomy (LC) is being used more frequently in patients undergoing gallbladder removal. Most initial studies have centered on the limited experience of a few select surgeons or institutions and may not accurately reflect the current state of LC. We used written and telephone survey tools to 103 community hospitals in Michigan to identify the utilization of LC, the criteria for training and credentialing, and patient outcome. Of 103 hospitals, 75 (73%) were involved with LC and 56% of these had < 100 beds. We found a large variation in the indications, contraindications, equipment, methods, and credentialing criteria. Major complications, including some not previously reported, were identified and occurred more frequently than previously described. LC is being widely applied and the majority of hospitals have < 100 beds. LC may carry higher risks than previously reported. Collected series and registry data that include community hospital experiences should better delineate the outcome of LC.

Factors influencing pregnancy outcome after trauma.

Trauma complicating pregnancy represents a significant threat to maternal survival and successful pregnancy outcome. Combining trauma center and perinatal center capabilities may provide improved outcome for pregnant trauma victims. The authors report their experience with 39 patients over a 10-year period to identify factors that influenced pregnancy outcome. There was 100 per cent maternal survival with a 77 per cent successful pregnancy rate. Unsuccessful pregnancy was associated with significantly higher injury severity score (ISS); regional abdominal abbreviated injury scores (AIS) and hospital charges; longer hospital and intensive care unit lengths of stay; a higher incidence of intubation and placenta abruptio; and a lower admission systolic blood pressure. Fetal ultrasound or Doppler were routinely used and contributed to trauma management. These findings support close cooperation and coordination of trauma and perinatal services to achieve optimal maternal and pregnancy outcomes.

Increased acylcarnitine clearance and excretion in septic rats.

Carnitine has been hypothesized to be a semi-essential nutrient in the nutrition of critically ill patients. The purpose of this study was to evaluate the effect of sepsis upon carnitine metabolism in the rat, using the model of cecal ligation and puncture. Three treatment groups, septic, sham, and non-operative controls, were used. The septic rats had significantly increased (p less than 0.05) excretion of acylcarnitine and over six-fold higher urinary acylcarnitine/free carnitine ratio, relative to the other two groups. The septic rats also had significantly higher liver and plasma free and total carnitine compared to the other two groups. A possible explanation for the increased urinary acylcarnitine excretion is that carnitine may be acting to remove toxic metabolites from the body. The septic model of cecal ligation and puncture was suitable for the study of carnitine metabolism during sepsis in the rat.

Surgical residents as teachers.

Surgical program directors have assumed that residents take on the role of teachers of medical students, and they have seldom questioned this assumption. The purpose of this study was to: determine the extent to which surgical residents teach and evaluate medical students; assess how surgical residents are prepared for and evaluated on their teaching responsibilities; and to identify surgical program directors' opinions about residents as teachers. Written surveys were sent to program directors of surgical residencies. A response rate of 79 percent was achieved. All programs taught medical students and involved residents in the process. Surgical residents taught medical students in a variety of settings and were responsible for student evaluation Approximately half of the programs, however, did not offer formal instruction in teaching skills to their residents and 60 percent of program directors did not believe it was important. In addition residents rarely received evaluations from medical students or program directors on their teaching.

Failure of BCAA supplementation to promote nitrogen retention in injured patients.

The purpose of this study was to determine if supplementing total parenteral nutrition (TPN) with lipids or the branched chain amino acids (BCAA) leucine, isoleucine, and valine influences nitrogen balance in the injured patient. Four TPN study solutions were used, with each patient receiving two of the solutions for 4 days each. Group A received solutions consisting of 19% and 44% BCAA, with nonnitrogen calories supplied by 100% carbohydrate. Group B received a 7:3 carbohydrate-to-lipid ratio of nonnitrogen calories as a fuel source. Neither BCAA supplementation nor varying fuel substrates promoted a difference in nitrogen retention. The added cost of BCAA supplementation, along with the lack of an effect upon nitrogen accretion, indicates that greater benefits must be demonstrated before widespread use of BCAA supplementation can be recommended in the injured patient.

DRGs and outliers in surgical critical care.

The authors evaluated the charges, outcome, and characteristics of patients requiring prolonged stay in the Surgical Intensive Care Unit (SICU) as if all reimbursement was from the Medicare DRG system. The records of patients staying in the SICU longer than 20 days over an 18 month period were reviewed. Age, mortality, service, length of stay, hospital charge, and projected DRG reimbursement were recorded. Patients whose hospital stay exceeded the maximum expected for their DRG were considered day outliers. The 51 study patients had a mean age of 59 +/- 17.6 years. They comprised 1.3 per cent of all patients in the SICU and 30.7 per cent of all SICU patient days during the study period. Mortality was 39.2 per cent. Thirty-two patients (62.7%) were day outliers. The mean hospital charge per patient was $59,552 while the mean projected DRG reimbursement was $10,435, for a total projected loss in billed charges of $2,504,428. DRG reimbursement for patients requiring prolonged SICU stay is inadequate to meet their charges and may severely limit future SICU use.

In vitro preservation of traumatic human skin autografts in a massive degloving injury.

The in vitro preservation of human skin autografts is a valuable technique in the management of severe degloving injuries. The authors describe the storage of traumatically induced human skin autografts involving nearly one third of the total body surface of a patient. These autografts were preserved in tissue-culture medium for 19 days and then transplanted onto the patient's prepared wounds, successfully acting as biologic dressings and permanent grafts. To the authors' knowledge, this is the largest clinical application of skin-storage techniques for the preservation of traumatic human skin autografts that is known to have been reported.