Urgent surgery in patients with a recently implanted coronary drug-eluting stent: a phase II study of 'bridging' antiplatelet therapy with tirofiban during temporary withdrawal of clopidogrel.

BACKGROUND: Patients with a recently implanted coronary drug-eluting stent (DES) who need urgent surgery are at increased risk of surgical bleeding unless clopidogrel is discontinued beforehand, but clopidogrel discontinuation has been associated with a high rate of adverse events due to stent thrombosis. This pilot study tested the hypothesis that the i.v. perioperative administration of the short-acting antiplatelet agent tirofiban allows the safe withdrawal of clopidogrel without increasing the rate of surgical bleeding. METHODS: Phase II study with a Simon two-stage design. RESULTS: Thirty patients with a recently implanted DES [median (range) 4 (1-12) months] and high-risk characteristics for stent thrombosis underwent urgent major surgery or eye surgery. Clopidogrel was to be withdrawn 5 days before surgery, and tirofiban started 24 h later, continued until 4 h before surgery, and resumed 2 h after surgery until oral clopidogrel was resumed. The use of aspirin was decided by the surgeon. There were no cases of death, myocardial infarction, stent thrombosis, or surgical re-exploration due to bleeding during the index admission, with a risk estimate of 0-11.6% (one-tail 97.5% CI). There was one case of thrombolysis in myocardial infarction (TIMI) major and one of TIMI minor bleeding in the postoperative phase; another four patients were transfused without meeting the TIMI criteria for major or minor bleeding. CONCLUSIONS: In patients with a recently implanted DES and high-risk characteristics for stent thrombosis needing urgent surgery, a 'bridging strategy' using i.v. tirofiban may allow temporary withdrawal of oral clopidogrel without increasing the risk of bleeding.

Platelet-derived growth factor effects on purified testicular peritubular myoid cells: binding, cytosolic Ca2+ increase, mitogenic activity, and extracellular matrix production enhancement.

The response of purified rat testicular peritubular myoid cells (PMC) to platelet-derived growth factor (PDGF) was studied. Freshly isolated PMC were devoid of measurable amounts of PDGF-binding sites. However, after 1 day in culture in serum-free conditions, specific high affinity receptors were detected. The estimated binding sites per cell revealed that PMC express more receptors for PDGF-BB, followed by PDGF-AB and PDGF-AA. PDGF treatment of cultured PMC increased the cytosolic Ca2+ concentration, showing a rank order of potencies with PDGF-BB > PDGF-AB > PDGF-AA. PMC proliferation, as measured by direct cell counting, was also stimulated by all three PDGF isoforms, with the same order of potencies observed for the increase in intracellular Ca2+. This effect was inhibited by antibodies to PDGF. Moreover, PDGF treatment increased the release of type IV collagen and fibronectin, and induced the release of type V collagen and laminin. These results demonstrate that testicular PMC are induced to express functionally active PDGF receptors in response to cell culturing. These data suggest that PMC may be a target for PDGF and that PDGF-mediated effects in vivo are dependent on factors regulating the expression of the receptors. The role that PDGF may play in normal and pathological testicular processes is discussed.

The long-duration response to L-dopa in the treatment of early PD.

OBJECTIVE: To investigate the long-duration response (LDR) to L-dopa resulting from different regimens of L-dopa. BACKGROUND: In clinical practice, L-dopa is usually administered without considering the LDR due to the drug. Moreover, it has not been established whether in early PD a multiple daily intake of small doses of L-dopa may induce a sustained LDR. METHODS: Twenty-four patients with early PD underwent a double-blind, crossover trial, comparing three different 15-day treatment periods with L-dopa: treatment A (250 mg every 24 hours); treatment B (250 mg every 8 hours); and treatment C (125 mg every 8 hours). After completion, 20 patients underwent a subsequent open-label randomized trial with prolonged treatments (250 mg every 24 hours or 125 mg every 8 hours) up to 3 months. LDR was measured at the end of each treatment. RESULTS: All patients achieved a sustained LDR after treatments A and B, whereas only 17% of patients reached a sustained LDR after treatment C. Overall, the LDRs resulting from treatments A and B had similar magnitude and were larger than the LDR deriving from treatment C. After 3 months of prolonged treatments, only three of 10 patients treated with 125 mg every 8 hours increased their LDR, whereas all 10 patients treated with 250 mg every 24 hours had a maximal and stable LDR. CONCLUSIONS: Sustained LDR to L-dopa is dependent on the amount of the single doses of the drug. A regimen scheduling small, divided doses during the day, as done in clinical practice, is a questionable therapy for the achievement of a sustained LDR.

Modulation of laminin synthesis in human neuroblastoma cells during retinoic acid induced differentiation.

A comparable pattern of morphological neuronal differentiation was induced in the human neuroblastoma cell line SMS-KCNR by treatment with either retinoic acid (RA) or exogenous laminin (LM). LM expression and synthesis by SMS-KCNR was increased upon RA treatment which involved the cell bound, rather than the secreted protein. These data suggest an involvement of LM in the neuroblastoma differentiation process manifested both as an ability of LM to induce a morphological neuronal differentiation and as a selective control on LM metabolism during RA induced neuronal differentiation.

Apolipoprotein E polymorphisms and Parkinson's disease.

The apolipoprotein E (APOE) gene polymorphism has been studied in Parkinson's disease (PD) with conflicting results. Recently, a newly described functional polymorphism in the regulatory region of the APOE gene, (-491 A/T), has been associated with late-onset Alzheimer's disease. We studied the association between these two polymorphisms of the APOE gene with PD in a sample of 126 PD patients and in 119 controls from the same geographic background. Allelic and genotypic frequencies were not different between PD cases and population controls for either the APOE or -491 A/T polymorphism. The age at onset of the disease was not different according to the specific genotypes of the two polymorphisms of the APOE gene.

Osteoporosis in patients affected with thalassemia. Our experience.

The authors examine 72 patients affected with homozygous B-thalassemia; The study was conducted by clinical-hematological and radiologic examination. The Singh method is used to compare clinical data with the degree of osteoporosis. The results indicate that there is a high frequency of osteoporotic abnormalities in thalassemia. The authors postulate that osteoporotic lesions are principally caused by hyperplasia of the marrow, the overactive bone marrow widening the medullary space and the increased intramedullary pressure causing osteoporosis.

[Variations of blood bilirubin levels in the newborn with and without retinopathy of prematurity (ROP)]. / Variazioni dei livelli bilirubinemici nei neonati con e senza retinopatia della prematurità (ROP).

Retinopathy of prematurity (ROP) is a multifactorial disease where production of free radicals is a pathogenic factor. Bilirubin is regarded today as the most powerful antioxidant substance "in vitro". To test such effect "in vivo" we studied 219 premature infants, admitted to our Neonatal Intensive Case Unit from April 1991 to October 1992, evaluating their serum bilirubin levels from day two to seven and mean bilirubin level of first week for each child. We also calculated the mean rate of daily increase of bilirubin. Our results show that bilirubin parameters considered are higher in neonates which will develop ROP of every stage than in the control ones. These results therefore do not support the concept that bilirubin could have a role in the prevention of ROP.

[Realities and perspectives of perinatal care in Sicily. Experience at an outborn neonatal unit]. / Realtà e prospettive dell'assistenza perinatale in Sicilia. L'esperienza di un Centro con neonati esculsivamente "outborn".

The Authors studied some mortality indices in the neonatal intensive and subintensive care unit of the University of Catania in order to assess the degree of efficiency of perinatal assistance. This Unit is the largest in southeastern Sicily and admits only outborn newborns from the city of Catania, the Catania province and other provinces. Comparison of the 1991-92 and the 1993-94 data revealed a marked reduction in the mortality rate, however this fall was only marginal in newborns of, or under 1,000 g. There was a marked decrease in the mortality rate from respiratory distress, especially in ventilated newborns receiving additional surfactant. Comparison of the data showed that in both study periods the mortality rate was much higher in newborns over 6 hours of life, in those presenting hematic pH values under 7.25 at admission and in those coming from other provinces. These results underline that it is essential for the political authorities to boost neonatal assistance in the delivery room and to ensure adequate transport of distressed newborns.

Management of patients with recently implanted coronary stents on dual antiplatelet therapy who need to undergo major surgery.

About 5% of patients undergoing coronary stenting need to undergo surgery within the next year. The risk of perioperative cardiac ischemic events, particularly stent thrombosis (ST), is high in these patients, because surgery has a prothrombotic effect and antiplatelet therapy is often withdrawn in order to avoid bleeding. The clinical and angiographic predictors of ST are well known, and the proximity to an acute coronary syndrome adds to the risk. The current guidelines recommend delaying non-urgent surgery for at least 6 weeks after the placement of a bare metal stent and for 6-12 months after the placement of a drug-eluting stent, when the risk of ST is reduced. However, in the absence of formal evidence, these recommendations provide little support with regard to managing urgent operations. When surgery cannot be postponed, stratifying the risk of surgical bleeding and cardiac ischemic events is crucial in order to manage perioperative antiplatelet therapy in individual cases. Dual antiplatelet therapy should not be withdrawn for minor surgery or most gastrointestinal endoscopic procedures. Aspirin can be safely continued perioperatively in the case of most major surgery, and provides coronary protection. In the case of interventions at high risk for both bleeding and ischemic events, when clopidogrel withdrawal is required in order to reduce perioperative bleeding, perioperative treatment with the short-acting intravenous glycoprotein IIb-IIIa inhibitor tirofiban is safe in terms of bleeding, and provides strong antithrombotic protection. Such surgical interventions should be performed at hospitals capable of performing an immediate percutaneous coronary intervention at any time in the case of acute myocardial ischemia.

Phosphorylation and glycosylation of nucleoporins.

The nuclear pore complex mediates macromolecular transport between the nucleus and cytoplasm. Many nuclear pore components (nucleoporins) are modified by both phosphate and O-linked N-acetylglucosamine (O-GlcNAc). Among its many functions, protein phosphorylation plays essential roles in cell cycle progression. The role of O-GlcNAc addition is unknown. Here, levels of nucleoporin phosphorylation and glycosylation during cell cycle progression are examined. Whereas nuclear pore glycoproteins are phosphorylated in a cell-cycle-dependent manner, levels of O-GlcNAc remain constant. The major nucleoporin p62 can be phosphorylated in vitro by protein kinase A and glycogen synthase kinase (GSK)-3alpha but not by cyclin B/cdc2 or GSK-3beta. The consensus sites of these kinases resemble sites which can be glycosylated by O-GlcNAc transferase. These data are consistent with a model that O-GlcNAc limits nucleoporin hyperphosphorylation during M-phase and hastens the resumption of regulated nuclear transport at the completion of cell division.

Schistosoma mansoni: immunodiagnosis is improved by sodium metaperiodate which reduces cross-reactivity due to glycosylated epitopes of soluble egg antigen.

ELISA with soluble egg antigen (SEA) from Schistosoma mansoni is widely used in the diagnosis of schistosomiasis, but cross-reactivity with other intestinal helminths, overestimating the true prevalence, represents a great limitation. The role of glycoproteins of SEA in cross-reactions was investigated. SEA was oxidized with sodium metaperiodate (SMP) in ELISA and immunoblot. One hundred schistosomiasis-negative individuals sera were submitted to SMP-ELISA improving the specificity from 73% without SMP treatment to 97% with SMP. On the other hand, 94 S. mansoni-positive sera were evaluated showing that 99% were positive in ELISA either with or without SMP treatment, indicating the maintenance of high sensitivity under SMP treatment. By immunoblot, 24 sera from persons with schistosomiasis and 10 sera from schistosomiasis-free persons were assayed under reducing and nonreducing conditions with or without SMP, looking for specific infection markers and cross-reactivity markers. Reactivity from positive sera showed that specific molecules were mainly low-molecular-mass antigens and seem to have predominant proteic epitopes. The unspecific molecules reacting with some schistosomiasis-negative individuals harboring other intestinal parasites (false-positive sera) were mostly larger than 60 kDa and seemed to be basically glycosylated. Glycosylated epitopes have an important role in cross-reaction and SMP can successfully be used to reduce the false reactivity of SEA with no decrease in sensitivity, especially in ELISA as an immunodiagnostic screening surveillance method, which is useful in areas of low schistosomiasis transmission.

Skeletal changes in thalassemia major.

The authors clinically and radiographically examined 72 patients with homozygous beta thalassemia. The clinical data were compared to the degree of osteoporosis calculated by Singh's method. The results indicate a high incidence of skeletal changes in patients with thalassemia, including lower limb-length discrepancy (16.6%), upper limb-length discrepancy (5.5%), axial deviation of the limbs (8.3%), osteochondrosis (2.7%), and osteopenia (25%). Based on their observations, the authors identify skeletal changes of adulthood (osteopenia) and childhood (limb-length discrepancy, axial deviation, osteochondrosis). The authors hypothesize that osteoporotic changes are caused principally by hyperplasia of the bone marrow, which widens the medullary space and increases intramedullary pressure, leading eventually to osteoporosis.

Body weight, levodopa pharmacokinetics and dyskinesia in Parkinson's disease.

We conducted a pharmacokinetic study in 164 patients with sporadic Parkinson's disease (PD) to address the relationship between body weight and levodopa pharmacokinetics. Patients underwent an oral acute levodopa test with 250 mg levodopa and pharmacokinetic variables were further assessed. Plasmatic levodopa area under the curve (AUC-l) and body weight were significantly and inversely correlated. Women were significantly lighter and more dyskinetic than men, and had greater AUC-l values. Our data suggest that during long-term treatment, lighter PD patients, especially women, may receive a greater cumulative dosage of levodopa per kilogram of body weight. This could explain gender differences for the development of levodopa-induced peak-dose dyskinesias observed during the course of the disease.

Plasma levels of vitamin E in Parkinson's disease.

Oxidative stress has been implicated as a major contributor to selective neuronal death in Parkinson's disease (PD). Vitamin E is an antioxidant that may protect the brain from free radical-induced oxidative damage. It is, therefore, reasonable to hypothesize that low levels of vitamin E concentrations may increase the risk of developing PD. To elucidate the possible role of vitamin E in the pathogenesis of PD, we assessed the plasma levels of vitamin E, measured by high-performance liquid chromatography (HPLC), in 54 patients with PD. Vitamin E concentrations were also assessed in 93 age and sex matched normal individuals. The mean plasma levels of vitamin E did not differ significantly between these two groups (22.5+/-8.15 &mgr;mol/l for PD patients and 21.0+/-7.9 &mgr;mol/l for controls). The results of our study suggest that plasma vitamin E concentrations do not play a major role in the pathogenesis of PD.

GH secretion in thalassemia patients with short stature.

The physiological role of GH secretion on growth retardation remains to be elucidated especially in patients with beta-thalassemia. In the present study, we investigated IGF-1 circulating levels as well as GH release following GHRH alone or combined with some inhibitors of somatostatin: pyridostigmine and arginine. In thalassemic patients lower IGF-1 circulating levels appear to be negatively correlated with both aspartate aminotransferase and alanine aminotransferase as well as with ferritin circulating levels indicating a probable role of hepatic hemosiderosis in IGF-1 production. The authors however suggest that reduced IGF-1 secretion is not the main cause of growth retardation since this would have elicited an enhanced response of GHRH in the presence of a normal hypothalamic pituitary axis. In contrast, they noticed that GH response to GHRH when expressed as area under the curve was lower in thalassemic patients compared to controls. The combination of GHRH with either pyridostigmine or arginine induced a GH secretion in thalassemics which was comparable to that of controls. The results of this study lead to conclude that the alteration of GH secretion is due, in such patients, to an increased somatostatin activity.

Safety of sentinel node biopsy in pregnant patients with breast cancer.

BACKGROUND: Lymphoscintigraphy (LS) and sentinel lymph node biopsy (SLNB) have typically been contraindicated for pregnant patients diagnosed with breast cancer because they are considered unsafe. PATIENTS AND METHODS: Twenty-six premenopausal non-pregnant patients who were candidates for LS underwent peritumoral injection of approximately 12 MBq of 99mTc-HSA nanocolloids. Static [15 min and 16 h post-injection (p.i.)] and whole-body (16 h p.i.) scintigraphic images were acquired. Activity concentration in the urine (0-2, 2-4, 4-8, 8-16 h p.i.) was evaluated by a gamma-counter. Activity in the bloodstream was measured at 4 and 16 h p.i. Thermoluminescent dosimeters (TLD) were placed, before tracer injection, on the injection site, between injection site and epigastrium (two points), and on the epigastrium, umbilicus and hypogastrium, and were removed before surgery. RESULTS: Scintigraphic images showed no radiotracer concentration except in the injection site and in the sentinel node. In all patients, the total activity excreted within the first 16 h was <2% of the injected activity. Activity in the blood pool was, at each time point, <1% of the injected activity. In 23 of 26 patients, all absorbed dose measurements were lower than the sensitivity of the TLD (<10 microGy); in the remaining three patients, the absorbed doses at the level of epigastrium, umbilicus and hypogastrium were in the following ranges: 40-320, 120-250 and 30-140 microGy, respectively. CONCLUSIONS: According to our standard technique (12 MBq of 99mTc-HAS), LS and SLNB can be performed safely during pregnancy, since the very low prenatal doses from this diagnostic procedure, when properly performed, do not significantly increase the risk of prenatal death, malformation or mental impairment.

Nuclear glycogen and glycogen synthase kinase 3.

Glycogen is the principal storage form of glucose in animal cells. It accumulates in electron-dense cytoplasmic granules and is synthesized by glycogen synthase (GS), the rate-limiting enzyme of glycogen deposition. Glycogen synthase kinase-3 (GSK-3) is a protein kinase that phosphorylates GS. Two nearly identical forms of GSK-3 exist: GSK-3 alpha and GSK-3 beta. Both are constitutively active in resting cells and their activity can be modulated by hormones and growth factors. GSK-3 is implicated in the regulation of many physiological responses in mammalian cells by phosphorylating substrates including neuronal cell adhesion molecule, neurofilaments, synapsin I, and tau. Recent observations point to functions for glycogen and glycogen metabolism in the nucleus. GSK-3 phosphorylates several transcription factors, and we have recently shown that it modifies the major nuclear pore protein p62. It also regulates PK1, a protein kinase required for maintaining the interphase state and for DNA replication in cycling Xenopus egg extracts. Recently, glycogen was shown to be required for nuclear reformation in vitro using ovulated Xenopus laevis egg lysates. Because neither glycogen nor GSK-3 has been localized to the nuclear envelope or intranuclear sites, glycogen and GSK-3 activites were measured in rat liver nuclei and nuclear reformation extracts. Significant quantities of glycogen-like material co-purified with the rat-liver nuclear envelope. GSK-3 is also highly enriched in the glycogen pellet of egg extracts of Xenopus that is required for nuclear assembly in vitro. Based on the finding that enzymes of glycogen metabolism copurify with glycogen, we propose that glycogen may serve a structural role as a scaffold for nuclear assembly and sequestration of critical kinases and phosphatases in the nucleus.