Crystal structure at 2.6-A resolution of human macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) was the first cytokine to be described, but for 30 years its role in the immune response remained enigmatic. In recent studies, MIF has been found to be a novel pituitary hormone and the first protein identified to be released from immune cells on glucocorticoid stimulation. Once secreted, MIF counterregulates the immunosuppressive effects of steroids and thus acts as a critical component of the immune system to control both local and systemic immune responses. We report herein the x-ray crystal structure of human MIF to 2.6 angstrom resolution. The protein is a trimer of identical subunits. Each monomer contains two antiparallel alpha-helices that pack against a four-stranded beta-sheet. The monomer has an additional two beta-strands that interact with the beta-sheets of adjacent subunits to form the interface between monomers. The three beta-sheets are arranged to form a barrel containing a solvent-accessible channel that runs through the center of the protein along a molecular 3-fold axis. Electrostatic potential maps reveal that the channel has a positive potential, suggesting that it binds negatively charged molecules. The elucidated structure for MIF is unique among cytokines or hormonal mediators, and suggests that this counterregulator of glucocorticoid action participates in novel ligand-receptor interactions.     

Matrix metalloproteinases contribute to the blood-brain barrier disruption during bacterial meningitis

In this study, we investigated the involvement of matrix metalloproteinases (MMPs) in the pathophysiology of bacterial meningitis. By using an enzyme immunoassay, high concentrations of MMP-9 were detected in the cerebrospinal fluid (CSF) of adult patients with bacterial meningitis but not in controls, and in patients with Guillain-Barré syndrome. Moreover, we observed significantly elevated concentrations of the tissue inhibitor of metalloproteinase-1 (TIMP-1) in the CSF of patients with bacterial meningitis, compared with controls. In a rat model of meningococcal meningitis, intracisternal injection of heat-killed meningococci caused a disruption of the blood-brain barrier (BBB), an increase in intracranial pressure, and CSF pleocytosis paralleled by the occurrence of MMP-9 activity in the CSF 6 hours after meningococcal challenge. The MMP inhibitor batimastat (BB-94) significantly reduced the BBB disruption and the increase in intracranial pressure irrespective of the time of batimastat administration (15 minutes before and 3 hours after meningococcal challenge) but failed to significantly reduce CSF white blood cell counts. In conclusion, our results suggest that MMPs are involved in the alterations of BBB permeability during experimental meningococcal meningitis.     

Donor factors affecting outcome after pancreas transplantation

In this study, we demonstrated that Px grafts from donors older than 45 years are associated with an increased risk of developing poor glycemic control and premature loss of Px function. Previous studies corroborate our finding that age of the donor is the principal donor characteristic impacting postoperative Px survival. Whereas prior studies also implicated hyperamylasemia as a factor which contributes adversely to outcome, we were unable to demonstrate a significant influence of donor hyperamylasemia on long-term graft survival, although it did correlate with the degree of immediate postoperative pancreatitis and with the need for oral hypoglycemic agents. Similarly, elevated blood glucoses in the donor, which can be a result of many other factors unrelated to the quality of the graft, did not predict a poor outcome in the recipient. NHB donor pancreata did as well as HB pancreata with regards to all postoperative functional parameters. A marginally increased risk of developing major complications was associated with older donors. Despite the frequent use of non-ideal donors, including older and NHB donors, excellent overall Px graft survival can be achieved. Although the quality of the pancreas graft was not directly addressed in this study, we believe irrespective of hyperglycemia or hyperamylasemia, subjective assessment of organ quality by an experienced transplant surgeon is the most important determinant of suitability.     

Osteoporosis after orchiectomy for prostate cancer

PURPOSE: The possibility of increased osteoporosis and osteoporotic fractures following therapeutic orchiectomy in men with prostate cancer was investigated. MATERIALS AND METHODS: A total of 235 men with nonstage A prostate cancer diagnosed between 1983 and 1990 was analyzed for therapeutic orchiectomy, other osteoporotic risk factors and subsequent hospital treatment for osteoporotic fractures. The 17 castrated men alive in 1995 were interviewed, and femoral neck bone mineral density was compared to that of 23 controls of similar age. RESULTS: Risk factors for osteoporosis, including smoking, slender habitus and atrophic testes, were common among men treated with orchiectomy. Of the men in the study cohort 10 had osteoporotic fractures: 8 of 59 treated with and 2 of 176 without orchiectomy (13.6 versus 1.1%, p < 0.001). First fracture cumulative incidence rates 7 years after castration or diagnosis were 28 and 1%, respectively (p < 0.001). Osteoporotic fractures were much more common than pathological fractures or those due to major trauma (1 each). Bone mineral density averaged 0.91, 0.84, 0.79 and 0.66 gm./cm.2 in 9 controls without prostate cancer, 14 men with prostate cancer before orchiectomy, 9 men at 9 to 60 and 8 men at 60 to 115 months after orchiectomy, respectively. Of the 16 men surviving for longer than 60 months after orchiectomy 6 had osteoporotic fractures, as did 5 of 6 and 5 of 7 with a bone mineral density of less than 0.70 gm./cm.2 and less than 75% of normal for age, respectively. CONCLUSIONS: Orchiectomy for prostate cancer is frequently followed by severe osteoporosis, some of which had developed before castration. Appropriate therapy should be identified that does not diminish the antitumorigenic effectiveness of androgen ablation.     

Stent thrombosis with different types of intracoronary stents: is it still a problem?

OBJECTIVE: The reported results of intracoronary stenting with Palmaz-Schatz stents using the low dose anticoagulation protocol have been encouraging and no stent thrombosis was observed. The effectiveness of such method extending to the use of other types of stents was therefore evaluated in this study. METHODS: All patients followed the anticoagulation protocol (heparin and warfarin) using non-heparin-coated stents. From September 1995, 92 patients received intracoronary stenting (69 men, 23 women, mean age 60.9 years). Altogether 117 stents were implanted in 99 target arteries and 106 lesions. RESULTS: A total of 50.4% of the stents were bare stents (stents without protective sheaths). Both coil stents and slotted tubular stents were used. Stenting was performed without the guidance of intravascular ultrasonography and high-pressure poststenting inflation was used in only 24.0% of patients with less than optimal angiographic results. The mean (+/- SD) coronary minimum luminal diameter changed from 0.63 +/- 0.39 mm to 3.12 +/- 0.48 mm immediately after stenting. Both stent thrombosis rate and femoral bleeding complication rate remained at 0%. Four bare stents could not be deployed in the first instance but without sequels. No morbidity nor mortality was recorded. The mean hospital stay remained at a mean of 4.5 days. All patients (100%) were followed up regularly. The mean (+/- SD) clinical follow-up period was 229 +/- 173 days. Clinical symptoms improved in all patients. CONCLUSIONS: These findings further support that the method is safe and stent thrombosis was not observed. Post-stenting recoil was more with coil stents. Dislodgment and potential risk of embolization could not be underestimated with bare stents. The restenosis rate between different types of stents remains to be determined.     

Variations of the C2H2 zinc finger motif in the yeast genome and classification of yeast zinc finger proteins

The PROSITE pattern Zinc_Finger_C2H2 was extended to permit the detection of all C2H2 zinc fingers and their parent proteins in the recently completed sequence of the yeast genome. Additionally, a new computer program was written that extracts other zinc binding motifs (non C2H2 'fingers'), overlapping with the classical zinc finger pattern, from the found set of yeast C2H2 fingers. The complete and correct detection of all fingers is a prerequisite for the classification of the yeast zinc finger proteins in functional terms. The detected 53 yeast C2H2 zinc finger proteins do not contain finger clusters with 10 or more repeats, as is frequently found in higher eukaryotes. Only three proteins contain four or more fingers in a cluster. Moreover, nearly all 27 yeast proteins with tandem arrays of two or three finger domains can be classified into nine subgroups with high sequence conservation in their finger clusters, in particular of their DNA recognition helices. These results and application of the recently elaborated finger/DNA recognition rules suggest that the yeast proteins belonging to the same subgroup may recognize identical or very similar DNA sites.     

Gastric emptying of 99mTc tagged solid food in gastric and duodenal ulceration

This study is to analyze gastric emptying (GE) of 99mTc tagged solid meals in 43 gastric ulcer (GU), 16 duodenal ulcer (DU) patients, and 15 normal subjects. Diagnosis of active ulcers had been made through high gastrointestinal endoscopy. The patients with GU were divided into three groups according to Johnson's classification. Gastric contents were measured at 15 minute intervals over a period of 150 minutes, with the person standing in front of a gamma-counter. The GE curve was obtained from the mean percentile of radioactivity of all the groups measured at 15 minute intervals. Results were submitted to statistical analysis. Significant delay in GE in DU patients compared to normals, type II and Type III group. However, GE of type I GU was not statistically different from the DU group nor of types II and III GU, occupying an intermediate e position.