Regulation of the extracellular ligand binding activity of integrins

Integrins are a large heterodimeric family of cell surface adhesion receptors that bind extracellular matrix and cell surface ligands. The extracellular ligand binding activity of integrins is a dynamic and highly regulated event involving the induction of conformational changes within the integrin structure. The adhesive properties of integrins can be controlled by altering the activation state of the integrin, either through conformational change or receptor clustering, using mechanisms that are regulated by intracellular proteins. In this review, we will discuss what is currently known about integrin structure and the ligand binding sites present within the receptor. In addition, the mechanisms by which the ligand binding event is regulated through conformational change will be addressed, and the potential role of intracellular cytoplasmic proteins will be discussed.

Transient hypoadrenalism during surgical critical illness

OBJECTIVE

To report the cortisol levels in 6 patients during and after severe inflammation.

DESIGN

Patients with severe inflammatory disease had basal and stimulated (cosyntropin) serum cortisol levels determined at the time of severe and less severe inflammation.

SETTING

Intensive care unit and wards of a tertiary care center.

PATIENTS

Six patients with continued evidence of severe inflammation, despite aggressive management of the underlying inflammatory disease.

INTERVENTIONS

Five of 6 patients received hydrocortisone at "physiologic" doses.

MAIN OUTCOME MEASURES

Basal and stimulated serum cortisol levels.

RESULTS

The mean+/-SD cortisol data for these patients were as follows: baseline cortisol level during inflammation, 350+/-121 nmol/L (n=6); stimulated cortisol level during inflammation, 571+/-326 nmol/L (n=6); baseline cortisol level with less inflammation, 833+/-339 nmol/L (P=.03 vs baseline level during inflammation) (n=5); and stimulated cortisol level with less inflammation, 1090+/-295 nmol/L (P=.03 vs stimulated level during inflammation) (n=4). Manifestations of inflammation decreased with hydrocortisone administration.

CONCLUSIONS

Severe inflammation may result in lower-than-expected serum cortisol levels, which then increase significantly as the inflammation decreases. Transient hypoadrenalism may aggravate the adverse effects of severe inflammation. These effects may be ameliorated by administering physiologic rather than pharmacologic doses of hydrocortisone.

The effect of pregnancy on cyclosporine levels in renal allograft patients

OBJECTIVE

To assess the effects of pregnancy on cyclosporine levels in six renal allograft patients.

METHODS

Maternal demographic, laboratory, clinical, and perinatal outcome data were recorded in six pregnant women with previous renal allografts receiving cyclosporine immunosuppression. The cyclosporine and serum creatinine levels were measured before pregnancy, during each trimester, and postpartum.

RESULTS

The mean (standard deviation [SD]) maternal age was 29.1 (3.8) years. Parity ranged from 0 to 3. Mean serum creatinine levels tended to be lower during pregnancy than before or after, as did the mean cyclosporine levels. After adjusting for dose, five of six patients had declines in cyclosporine level during pregnancy. The mean (SD) gestational age at delivery was 37.5 (2.8) weeks with a mean (SD) birth weight of 2837 (538) g.

CONCLUSION

Pregnancy in patients with renal allografts can lead to a substantial decline in cyclosporine levels.

Selective binding of N-acetylglucosamine to the chicken hepatic lectin

Among Ca2+-dependent (C-type) animal lectins, the chicken hepatic lectin (CHL) is unique in displaying almost complete selectivity for N-acetylglucosamine over other monosaccharide ligands. The crystal structures of the carbohydrate-recognition domain (CRD) from serum mannose-binding protein (MBP) and of a complex between the CRD from liver MBP and the methyl glycoside of N-acetylglucosamine were used to model the binding site in CHL. Substitution of portions of CHL into the MBP framework did not substantially increase selectivity. A bacterial expression system for the CRD of CHL was developed so that specific residues predicted to be near the 2-acetamido substituent of N-acetylglucosamine could be altered by site-directed mutagenesis. The results indicate that the ligand is bound to CHL in the same orientation as it binds to liver MBP. A tyrosine and a valine residue that probably contact the the N-acetyl group have been identified. These results, together with studies of ligand-binding selectivity, suggest that these residues form part of a binding pocket for the N-acetyl group, which confers selective binding of N-acetylglucosamine.

Automaticity of social behavior: direct effects of trait construct and stereotype-activation on action

Previous research has shown that trait concepts and stereotype become active automatically in the presence of relevant behavior or stereotyped-group features. Through the use of the same priming procedures as in previous impression formation research, Experiment 1 showed that participants whose concept of rudeness was printed interrupted the experimenter more quickly and frequently than did participants primed with polite-related stimuli. In Experiment 2, participants for whom an elderly stereotype was primed walked more slowly down the hallway when leaving the experiment than did control participants, consistent with the content of that stereotype. In Experiment 3, participants for whom the African American stereotype was primed subliminally reacted with more hostility to a vexatious request of the experimenter. Implications of this automatic behavior priming effect for self-fulfilling prophecies are discussed, as is whether social behavior is necessarily mediated by conscious choice processes.

A multicenter trial of FK506 (tacrolimus) therapy in refractory acute renal allograft rejection. A report of the Tacrolimus Kidney Transplantation Rescue Study Group

A multicenter trial was conducted to evaluate the efficacy and safety of tacrolimus in the treatment of refractory renal allograft rejection. Renal transplant recipients experiencing biopsy-proven recurrent acute allograft rejection were eligible if the current rejection episode was refractory to corticosteroids. A total of 73 patients were enrolled, of whom 59 (81%) had previously received at least one course of antilymphocyte antibody as rejection therapy. One-year follow-up was available in 93% of patients. Median time to tacrolimus rescue therapy was 75 days after transplantation (range, 18-1448 days). Therapeutic responses to tacrolimus included improvement in 78% of patients, stabilization in 11%, and progressive deterioration in 11%. The risk of experiencing progressive deterioration was related to the pretacrolimus serum creatinine level: serum creatinine < or = mg/dl, 3%; 3.1-5 mg/dl, 16% (P < 0.04); > 5 mg/dl, 23% (P < 0.02). Twelve-month (from the time of initiation of tacrolimus therapy) actuarial patient and graft survival rates were 93% and 75%. Graft loss occurred in 19 patients (25%) at a median time of 108 days. Fourteen episodes of recurrent rejection were diagnosed in 10 patients (14%), at a median time of 101 days. Eleven episodes of recurrent rejection were treated (three patients underwent transplant nephrectomy), with resolution achieved in nine patients. Antilymphocyte antibody therapy was not used to treat recurrent rejection. Serum creatinine values improved during tacrolimus therapy: median serum creatinine level before tacrolimus, 3.2 mg/dl; median at 1 year after tacrolimus, 1.8 mg/dl. Twelve infections were documented in 11 patients (15%), including cytomegalovirus infection in three patients (4%). Posttransplant lymphoproliferative disorder was diagnosed in a single patient. Tacrolimus whole blood levels averaged 15.0 +/- 9.9 ng/ml at day 7 of tacrolimus therapy and 9.4 +/- 5.1 ng/ml at 1 year, and were consistent among individual centers. Treatment outcome did not correlate with tacrolimus blood levels. The most commonly observed adverse events were neurological and gastrointestinal. Seventy-four percent of patients received tacrolimus for at least 1 year. Tacrolimus therapy was discontinued in 18% of patients for rejection (11% for progressive, unrelenting rejection, and 7% for recurrent rejection). Tacrolimus therapy was discontinued in 8% of patients due to adverse events. In conclusion, tacrolimus rescue therapy provides (1) prompt, effective reversal of refractory renal allograft rejection, (2) good long-term renal allograft function, (3) a low incidence of recurrent rejection, and (4) an acceptable safety profile in renal allograft recipients experiencing refractory rejection.

Automaticity of social behavior: direct effects of trait construct and stereotype-activation on action

Previous research has shown that trait concepts and stereotype become active automatically in the presence of relevant behavior or stereotyped-group features. Through the use of the same priming procedures as in previous impression formation research, Experiment 1 showed that participants whose concept of rudeness was printed interrupted the experimenter more quickly and frequently than did participants primed with polite-related stimuli. In Experiment 2, participants for whom an elderly stereotype was primed walked more slowly down the hallway when leaving the experiment than did control participants, consistent with the content of that stereotype. In Experiment 3, participants for whom the African American stereotype was primed subliminally reacted with more hostility to a vexatious request of the experimenter. Implications of this automatic behavior priming effect for self-fulfilling prophecies are discussed, as is whether social behavior is necessarily mediated by conscious choice processes.

Peritoneal dialysis technician: a process for role definition

Declining reimbursement and rising supply costs have led to use of technicians in peritoneal dialysis. This evolution has helped contain costs effectively while enhancing quality care. Recommendations for use of unlicensed assistive personnel by professional organizations include clear role definition, documented training, and delegation criteria. Applications of technician use in peritoneal dialysis allow nurses to delegate tasks to technicians in harmony with legal and professional standards.

Urine cytology and urine flow cytometry in renal transplantation--a prospective double blind study

Urine cytology (UC) has proved to correlate well with core and fine-needle aspiration kidney biopsies of renal allograft recipients undergoing acute rejection (AR). This study was undertaken to compare the relative usefulness of urine flow immunocytometry (UFC) (using fluorescinated antibodies anti-HLA-DR, anti-CD3 and antirenal epithelial cells) with UC in its ability to diagnose AR by analyzing 200 urine specimens during a prospective double-blind study of 40 renal transplant recipients. Clinical diagnosis was retrospectively assigned to one of the following categories: group I--AR, 15; group II--ischemic injury period (first 5 days postop.), 12; group III, 173 (including 168 stable grafts, 1 pyelonephritis and 4 cyclosporine toxicity), by investigators blinded to the urine results. Both tests were highly sensitive for the diagnosis of AR (UC = 86.6% vs. UFC = 100%; P = NS) with a specificity after the ischemic injury period of 78% by UC and 87.9% by UFC. Samples obtained during AR revealed higher levels of expression of HLA-DR as well as higher numbers of CD3-positive cells. These tests had specificity values of 95.3% and 97.6%, respectively, for the diagnosis of AR. The degree of immune activation (established by numbers of lymphocytes/lymphoblasts seen by UC) correlated with the severity of biopsy-proven ARs and with response to antirejection therapy. In conclusion, both test are highly accurate in diagnosing AR. The highest specificity value was obtained when both UC and UFC were utilized together (93%). We suggest that the routine use of these tests can provide an important adjunct to the evaluation of renal transplant recipients.

Interpersonal stress, depression, and disease activity in rheumatoid arthritis and osteoarthritis patients

The relationships among interpersonal stressors, depression, coping inefficiency, hormones (prolactin, cortisol, and estradiol), and disease activity were examined. The sample comprised 33 women with rheumatoid arthritis (RAs; age 37-78) and 37 women with osteoarthritis (OAs; age 47-91), who served as controls. In a regression analysis, interpersonal conflict events accounted for more than twice as much variance in depression in RAs than in OAs. In the RA patients, the immune-stimulating hormones prolactin and estradiol were significantly positively correlated with interpersonal conflicts, depression, coping inefficacy, and clinician ratings of disease activity, suggesting that RAs are more reactive to interpersonal stressors than are OAs, both psychologically and physiologically.

Risk of steroid withdrawal in pediatric renal allograft recipients (a 5-year follow-up)

Withdrawal of steroid therapy in renal allograft recipients remains controversial despite the many side effects of this treatment. We have previously presented data on 16 pediatric renal transplant recipients in whom prednisone was withdrawn 6 months or later post-transplantation. To assess the impact of steroid withdrawal, we retrospectively compared this group of patients (Group 1) with a group of 12 patients (Group 2) with renal transplants who continued on prednisone. The groups were compared as to age, sex, ethnicity, source of graft, number of HLA-DR mismatches and incidence of ATN in the immediate postoperative period. The only significant difference was that Group 2 was older. Group 1 had significantly fewer episodes of early acute rejection in the first 6 months post-transplantation than the control group (3/16 vs 8/12, p = 0.009) but nevertheless, without prednisone, had significantly more late acute rejections (11/16 vs 3/12, p = 0.03). Acute rejections occurred as late as 4 years after withdrawal of steroids. Only 5 of the 16 patients in Group 1 have maintained stable graft function without steroids. All of these patients are now alive more than 5 years after steroid withdrawal. In comparing these patients to the other 11, who failed a trial of steroid withdrawal, we found that a serum creatinine of less than 1.7 mg/dl at the time of withdrawal of steroids was predictive of a successful outcome (p = 0.03). In conclusion, withdrawing steroids in pediatric renal allograft recipients has a high risk of late acute rejection and subsequent graft loss, especially for those who have higher baseline creatinine levels.

Interpersonal stress, depression, and disease activity in rheumatoid arthritis and osteoarthritis patients

The relationships among interpersonal stressors, depression, coping inefficiency, hormones (prolactin, cortisol, and estradiol), and disease activity were examined. The sample comprised 33 women with rheumatoid arthritis (RAs; age 37-78) and 37 women with osteoarthritis (OAs; age 47-91), who served as controls. In a regression analysis, interpersonal conflict events accounted for more than twice as much variance in depression in RAs than in OAs. In the RA patients, the immune-stimulating hormones prolactin and estradiol were significantly positively correlated with interpersonal conflicts, depression, coping inefficacy, and clinician ratings of disease activity, suggesting that RAs are more reactive to interpersonal stressors than are OAs, both psychologically and physiologically.

En bloc transplantation of infant and child cadaver kidneys to adult recipients

From 1991 to 1992 eight child cadaveric kidneys were transplanted en block to adult recipients as part of a prospective study at The Mount Sinai Medical Center. Six of eight transplants came from infant donors less than two years of age. There were four technical complications. Two resulted in bilateral graft nephrectomy and return to dialysis, and two required unilateral graft nephrectomy with acceptable renal function from the single remaining kidney. At a mean follow-up of 11.8 months, overall graft survival is 75% with mean serum creatinine of 1.7 mg/dL. Of the infant transplants, 83% are functioning at a mean follow-up of 11.4 months. The average serum creatinine level for this group is 1.8 mg/dL. Our data support the use of en bloc child cadaveric kidneys, including infant donors less than two years of age. The use of this source increases the donor pool.