Detection and Assessment of α-Synuclein Oligomers in the Urine of Parkinson's Disease Patients

BACKGROUND

α-Synuclein (α-syn) is a major component of Lewy bodies, a pathologic marker of Parkinson's disease (PD) in post-mortem studies. The use of α-syn as a practical PD biomarker has been investigated by numerous researchers. However, reports of differences in α-syn levels in biofluids, such as cerebrospinal fluid, plasma, and saliva, between PD patients and controls are inconsistent. Recently, the measurement of α-syn oligomer levels has emerged as a novel approach to diagnose PD.

OBJECTIVE

Lysates and culture media from two different types of dopaminergic neuronal cells or urine samples from 11 non-PD and 21 PD patients were collected and analyzed.

METHODS

We developed and performed an enzyme-linked immuno-absorbent assay (ELISA) to detect various oligomeric α-syn using distinct pairs of antibodies.

RESULTS

We validated our ELISA using rotenone-induced alterations of α-syn levels in human dopaminergic neurons. Total urinary α-syn levels, measured using our ELISA method, showed no difference between PD and non-PD individuals, but a higher level of α-syn oligomer recognized by MJFR-14-6-5-2 in PD urine samples was observed. Levels of distinct oligomeric α-syn detected by ASyO5 were lower in PD urine samples. Three different α-syn ELISA results were analyzed with respect to the severity of PD, but only the correlation between total α-syn levels and PD index was significant.

CONCLUSION

Our findings suggest that detection of distinct oligomeric formations of α-syn and measurement of their levels in urine might be feasible for use in PD diagnostics.

Expression of transduced nucleolin promotes the clearance of accumulated α-synuclein in rodent cells and animal model

Alpha-synuclein (αSyn) is a major component of Lewy bodies, which are a known pathogenic marker of Parkinson's disease (PD). The dysfunction of protein degradation machinery causes αSyn accumulation. The reinforcement of αSyn degradation is a potential therapeutic target for PD because accumulated αSyn is responsible for the pathogenesis of PD. Nucleolin (NCL) is essential in the formation of the nucleolar structure. The function of NCL is correlated with oxidative stress-mediated cell death. A previous study demonstrated that NCL overexpression alleviated rotenone-induced neurotoxic effects, whereas knockdown of NCL had the opposite effect. These results suggest that NCL malfunction would exacerbate PD pathology. Thus, it was hypothesized that the introduction of ectopic NCL could rescue α-synucleinopathy in PD. This study investigated whether the ectopic expression of NCL facilitates αSyn clearance. Ectopic expression of NCL was accomplished via the transfection of green fluorescent protein (GFP) or GFP-NCL in mouse embryonic fibroblasts (MEF) or transduction of GFP or GFP-NCL using lentivirus in rat primary cortical neurons and mouse substantia nigra. NCL overexpression enhanced the clearance of accumulated or aggregated αSyn in MEFs and rat primary cortical neurons. The activity of the autophagy-lysosome pathway was enhanced by NCL expression. NCL transduction in the substantia nigra, which was co-injected with αSyn fibrils, rescued PD manifestation. The elevation of NCL levels may reflect a therapeutic strategy for α-synucleinopathy in PD.

Analysis of α-synuclein levels related to LRRK2 kinase activity: from substantia nigra to urine of patients with Parkinson's disease

Research on Parkinson’s disease (PD) has been focused on the development of PD diagnostic tools as much as the development of PD therapeutics. Several genetic culprits of PD, including DJ-1, Leucine-rich repeat kinase 2 (LRRK2), and α-synuclein (α-syn), have been investigated as markers of PD in human biofluids. Unfortunately, the approaches to develop PD diagnostic tools are impractical, and there is a considerable demand for an appropriate marker of PD. The measurement of α-syn in biofluids has recently been made more accurate by examining monomers and aggregates separately using enzyme-linked immunosorbent assay (ELISA). Previously, we reported on the development of two types of sandwich ELISA for total α-syn and MJFR-14-6-4-2 antibody-specific α-syn fibrillar oligomers. The pathogenic LRRK2 G2019S mutation is related to increased α-syn secretion in the extracellular space. We tested our established ELISA using differentiated SH-SH5Y cells transfected with LRRK2 G2019S. The secretory levels of fibrillar oligomeric α-syn divided by total α-syn were significantly increased in LRRK2 G2019S-expressing cells. Additionally, substantia nigra lysates or concentrated urine from PD patients and non-PD subjects were analyzed. We observed ambiguous changes in the levels of total or fibrillar oligomeric α-syn and their ratio between PD and non-PD. Despite the insignificant increase in the relative levels of fibrillar oligomeric α-syn to total α-syn in PD, the duration of disease progression after diagnosis significantly corresponded to the relative levels of fibrillar oligomeric α-syn to total α-syn in the urine. These results might provide greater understanding for the next stage of development of α-syn ELISAs.

G2019s LRRK2 promotes mitochondrial fission and increases TNFα-mediated neuroinflammation responses

Leucine rich-repeat kinase 2 (LRRK2) is involved in the pathogenesis of Parkinson's disease (PD). LRRK2 has kinase and GTPase activities, and mediates several cell functions, including vesicle trafficking, apoptosis, autophagy, mitochondrial dynamics, and neuroinflammation. G2019S (GS) is the most prevalent mutation of LRRK2. The mutation increases kinase activity, suggesting that this activity is crucial for PD pathogenesis. The activation and inhibition of LRRK2 kinase increases and reduces the levels of proinflammatory cytokines, respectively suggesting that the role of LRRK2 in neuroinflammation is critical for the pathology of PD. Previously, we demonstrated that microglial activation by lipopolysaccharide (LPS) increases mitochondrial fission via the activation of LRRK2 kinase, while LRRK2 kinase inhibition diminishes the fission morphology and release of tumor necrosis factor-alpha (TNFα) in BV2 or rat primary microglia and the brains of GS transgenic mice. In this study, the ectopic expression of GS LRRK2 in BV2 cells significantly elevated the expression of Drp1 along the fragmented mitochondria and decreased mitochondria size compared with controls. GS LRRK2-transfected BV2 cells displayed significantly increased TNFα release and neuronal death. Inhibition of LRRK2 kinase alleviated these features. TNFα levels in brains of GS mice were significantly increased compared to those in their littermates. These data further support our previous findings concerning LPS-induced neuroinflammation and mitochondrial fission in microglia via LRRK2 kinase activation.

Upregulation of the p53-p21 pathway by G2019S LRRK2 contributes to the cellular senescence and accumulation of α-synuclein

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies (LB) in neurons. α-Synuclein (αSyn) is a major component of LB and promote the PD pathogenesis via its accumulation by the impaired proteasomal or autophagic clearance. Numerous studies have revealed that the reduction of proteasome activity and autophagy is accelerated by cellular senescence. Leucine-rich repeat kinase 2 (LRRK2) contributes to PD progression and its most prevalent mutation, G2019S LRRK2, increases its activity. Our previous report has shown that the G2019S LRRK2 mutant promoted p53-induced p21 expression and neuronal cytotoxicity. The p53-p21 pathway plays a role in cellular senescence. We hypothesized that the loss of dopaminergic neurons by the stimulated p53-p21 pathway via the G2019S LRRK2 mutation might be associated with cellular senescence, thereby promoting the accumulation of αSyn. We confirmed that the ectopic expression of the phosphomimetic p53 mutant, p21, or G2019 in differentiated SH-SY5Y cells increased the following: 1) the expression of β-galactosidase, a marker of cellular senescence, and the activity of senescence-associated β-galactosidase, 2) endogenous αSyn protein level, but not its mRNA level, and 3) αSyn fibril accumulation in dSH-SY5Y via low proteasome and cathepsin D activities. Elevated oligomeric αSyn and the increase in β-galactosidase with induced p21 were observed in brain lysates of G2019S transgenic mice. Our results suggest that cellular senescence is promoted via the p53-p21 pathway due to the G2019S LRRK2 mutation. Eventually, decreased protein degradation by G2019S-mediated senescence could accelerate αSyn aggregate formation.

LRRK2 impairs autophagy by mediating phosphorylation of leucyl-tRNA synthetase

Leucine-rich repeat kinase 2 (LRRK2) is a causal gene of Parkinson disease. G2019S pathogenic mutation increases its kinase activity. LRRK2 regulates various phenotypes including autophagy, neurite outgrowth, and vesicle trafficking. Leucyl-tRNA synthetase (LRS) attaches leucine to tRNA^Leu and activates mTORC1. Down-regulation of LRS induces autophagy. We investigated the relationship between LRRK2 and LRS in regulating autophagy and observed interaction between endogenous LRRK2 and LRS proteins and LRS phosphorylation by LRRK2. Mutation studies implicated that T293 in the LRS editing domain was a putative phosphorylation site. Phospho-Thr in LRS was increased in cells overexpressing G2019S and dopaminergic neurons differentiated from induced pluripotent stem (iPS) cells of a G2019S carrier. It was decreased by treatment with an LRRK2 kinase inhibitor (GSK2578215A). Phosphomimetic T293D displayed lower leucine bindings than wild type (WT), suggesting its defective editing function. Cellular expression of T293D increased expression of GRP78/BiP, LC3B-II, and p62 proteins and number of LC3 puncta. Increase of GRP78 and phosphorylated LRS was diminished by treatment with GSK2578215A. Levels of LC3B, GRP78/BiP, p62, and α-synuclein proteins were also increased in G2019S transgenic (TG) mice. These data suggest that LRRK2-mediated LRS phosphorylation impairs autophagy by increasing protein misfolding and endoplasmic reticulum stress mediated by LRS editing defect. SIGNIFICANCE OF THE STUDY: Leucine-rich repeat kinase 2 (LRRK2) is the most common genetic cause of Parkinson disease (PD), and the most prevalent pathogenic mutation, G2019S, increases its kinase activity. In this study, we elucidated that leucyl-tRNA synthetase (LRS) was an LRRK2 kinase substrate and identified T293 as an LRRK2 phosphorylation site. LRRK2-meidated LRS phosphorylation or G2019S can lead to impairment of LRS editing, increased ER stress, and accumulation of autophagy markers. These results demonstrate that LRRK2 kinase activity can facilitate accumulation of misfolded protein, suggesting that LRRK2 kinase might be a potential PD therapeutic target along with previous studies.

Increase in anti-apoptotic molecules, nucleolin, and heat shock protein 70, against upregulated LRRK2 kinase activity

Leucine-rich repeat kinase 2 (LRRK2) is involved in Parkinson’s disease (PD) pathology. A previous study showed that rotenone treatment induced apoptosis, mitochondrial damage, and nucleolar disruption via up-regulated LRRK2 kinase activity, and these effects were rescued by an LRRK2 kinase inhibitor. Heat-shock protein 70 (Hsp70) is an anti-oxidative stress chaperone, and overexpression of Hsp70 enhanced tolerance to rotenone. Nucleolin (NCL) is a component of the nucleolus; overexpression of NCL reduced cellular vulnerability to rotenone. Thus, we hypothesized that rotenone-induced LRRK2 activity would promote changes in neuronal Hsp70 and NCL expressions. Moreover, LRRK2 G2019S, the most prevalent LRRK2 pathogenic mutant with increased kinase activity, could induce changes in Hsp70 and NCL expression. Rotenone treatment of differentiated SH-SY5Y (dSY5Y) cells increased LRKK2 levels and kinase activity, including phospho-S935-LRRK2, phospho-S1292-LRRK2, and the phospho-moesin/moesin ratio, in a dose-dependent manner. Neuronal toxicity and the elevation of cleaved poly (ADP-ribose) polymerase, NCL, and Hsp70 were increased by rotenone. To validate the induction of NCL and Hsp70 expression in response to rotenone, cycloheximide (CHX), a protein synthesis blocker, was administered with rotenone. Post-rotenone increased NCL and Hsp70 expression was repressed by CHX; whereas, rotenone-induced kinase activity and apoptotic toxicity remained unchanged. Transient expression of G2019S in dSY5Y increased the NCL and Hsp70 levels, while administration of a kinase inhibitor diminished these changes. Similar results were observed in rat primary neurons after rotenone treatment or G2019S transfection. Brains from G2019S-transgenic mice also showed increased NCL and Hsp70 levels. Accordingly, LRRK2 kinase inhibition might prevent oxidative stress-mediated PD progression.

Abbreviations: 6-OHDA: 6-hydroxydopamine; CHX: cycloheximide; dSY5Y: differentiated SH-SY5Y; g2019S tg: g2019S transgenic mouse; GSK/A-KI: GSK2578215A kinase inhibitor; HSP70: heat shock protein 70; LDH: lactose dehydrogenase; LRRK2: leucine rich-repeat kinase 2; MPTP: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; myc-GS LRRK2: myc-tagged g2019S LRRK2; NCL: nucleolin; PARP: poly(ADP-ribose) polymerase; PD: Parkinson’s disease; PINK1: PTEN-induced putative kinase 1; pmoesin: phosphorylated moesin at t558; ROS: reactive oxygen species

LRRK2 Kinase Activity Induces Mitochondrial Fission in Microglia via Drp1 and Modulates Neuroinflammation

Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common genetic cause of Parkinson's disease (PD). LRRK2 contains a functional kinase domain and G2019S, the most prevalent LRRK2 pathogenic mutation, increases its kinase activity. LRRK2 regulates mitochondria morphology and autophagy in neurons. LPS treatment increases LRRK2 protein level and mitochondrial fission in microglia, and down-regulation of LRRK2 expression or inhibition of its kinase activity attenuates microglia activation. Here, we evaluated the direct role of LRRK2 G2019S in mitochondrial dynamics in microglia. Initial observation of microglia in G2019S transgenic mice revealed a decrease in mitochondrial area and shortage of microglial processes compared with their littermates. Next, we elucidated the molecular mechanisms of these phenotypes. Treatment of BV2 cells and primary microglia with LPS enhanced mitochondrial fission and increased Drp1, a mitochondrial fission marker, as previously reported. Importantly, both phenotypes were rescued by treatment with GSK2578215A, a LRRK2 kinase inhibitor. Finally, the protein levels of CD68, an active microglia marker, Drp1 and TNF-α were significantly higher in brain lysates of G2019S transgenic mice compared with the levels in their littermates. Taken together, our data suggest that LRRK2 could promote microglial mitochondrial alteration via Drp1 in a kinase-dependent manner, resulting in stimulation of pro-inflammatory responses. This mechanism in microglia might be a potential target to develop PD therapy since neuroinflammation by active microglia is a major symptom of PD.

Leucine-Rich Repeat Kinase 2 (LRRK2) phosphorylates p53 and induces p21(WAF1/CIP1) expression

Background

Leucine-rich repeat kinase 2 (LRRK2) is a gene in which a mutation causes Parkinson’s disease (PD), and p53 is a prototype tumor suppressor. In addition, activation of p53 in patient with PD has been reported by several studies. Because phosphorylation of p53 is critical for regulating its activity and LRRK2 is a kinase, we tested whether p53 is phosphorylated by LRRK2.

Results

LRRK2 phosphorylates threonine (Thr) at TXR sites in an in vitro kinase assay, and the T304 and T377 were identified as putative phosphorylated residues. An increase of phospho-Thr in the p53 TXR motif was confirmed in the cells overexpressing G2019S, and human induced pluripotent stem (iPS) cells of a G2019S carrier. Interactions between LRRK2 and p53 were confirmed by co-immunoprecipitation of lysates of differentiated SH-SY5Y cells. LRRK2 mediated p53 phosphorylation translocalizes p53 predominantly to nucleus and increases p21^WAF1/CIP1 expression in SH-SY5Y cells based on reverse transcription-polymerase chain reaction and Western blot assay results. The luciferase assay using the p21^WAF1/CIP1 promoter-reporter also confirmed that LRRK2 kinase activity increases p21 expression. Exogenous expression of G2019S and the phosphomimetic p53 T304/377D mutants increased expression of p21^WAF1/CIP1 and cleaved PARP, and cytotoxicity in the same cells. We also observed increase of p21 expression in rat primary neuron cells after transient expression of p53 T304/377D mutants and the mid-brain lysates of the G2019S transgenic mice.

Conclusion

p53 is a LRRK2 kinase substrate. Phosphorylation of p53 by LRRK2 induces p21^WAF1/CIP1 expression and apoptosis in differentiated SH-SY5Y cells and rat primary neurons.

Electronic supplementary material

The online version of this article (doi:10.1186/s13041-015-0145-7) contains supplementary material, which is available to authorized users.

An early endosome regulator, Rab5b, is an LRRK2 kinase substrate

Leucine-rich repeat kinase 2 (LRRK2) has been identified as a causative gene for Parkinson's disease (PD). LRRK2 contains a kinase and a GTPase domain, both of which provide critical intracellular signal-transduction functions. We showed previously that Rab5b, a small GTPase protein that regulates the motility and fusion of early endosomes, interacts with LRRK2 and co-regulates synaptic vesicle endocytosis. Using recombinant proteins, we show here that LRRK2 phosphorylates Rab5b at its Thr6 residue in in vitro kinase assays with mass spectrophotometry analysis. Phosphorylation of Rab5b by LRRK2 on the threonine residue was confirmed by western analysis using cells stably expressing LRRK2 G2019S. The phosphomimetic T6D mutant exhibited stronger GTPase activity than that of the wild-type Rab5b. In addition, phosphorylation of Rab5b by LRRK2 also exhibited GTPase activity stronger than that of the unphosphorylated Rab5b protein. Two assays testing Rab5's activity, neurite outgrowth analysis and epidermal growth factor receptor degradation assays, showed that Rab5b T6D exhibited phenotypes that were expected to be observed in the inactive Rab5b, including longer neurite length and less degradation of EGFR. These results suggest that LRRK2 kinase activity functions as a Rab5b GTPase activating protein and thus, negatively regulates Rab5b signalling.

Epigenetics and transgenerational transfer: a physiological perspective

Epigenetics, the transgenerational transfer of phenotypic characters without modification of gene sequence, is a burgeoning area of study in many disciplines of biology. However, the potential impact of this phenomenon on the physiology of animals is not yet broadly appreciated, in part because the phenomenon of epigenetics is not typically part of the design of physiological investigations. Still enigmatic and somewhat ill defined is the relationship between the overarching concept of epigenetics and interesting transgenerational phenomena (e.g. 'maternal/parental effects') that alter the physiological phenotype of subsequent generations. The lingering effect on subsequent generations of an initial environmental disturbance in parent animals can be profound, with genes continuing to be variously silenced or expressed without an associated change in gene sequence for many generations. Known epigenetic mechanisms involved in this phenomenon include chromatin remodeling (DNA methylation and histone modification), RNA-mediated modifications (non-coding RNA and microRNA), as well as other less well studied mechanisms such as self-sustaining loops and structural inheritance. In this review we: (1) discuss how the concepts of epigenetics and maternal effects both overlap with, and are distinct from, each other; (2) analyze examples of existing animal physiological studies based on these concepts; and (3) offer a construct by which to integrate these concepts into the design of future investigations in animal physiology.

Oral uracil and Ftorafur plus leucovorin: pharmacokinetics and toxicity in patients with metastatic cancer

PURPOSE

To assess the pharmacokinetics of Ftorafur (tegafur, FT), 5-fluorouracil (5-FU), and uracil in 31 cancer patients who were enrolled in phase I studies of oral uracil and FT (UFT). The correlation between pharmacokinetic parameters and toxic effects of UFT was evaluated.

METHODS

Uracil and FT were orally administered in a 4:1 molar ratio at FT doses of 200-400 mg/m2 per day. Patients also received leucovorin at 150 mg/day. Daily doses were divided into three doses and administered at 8-h intervals for 28 consecutive days. Plasma FT concentrations were measured by high-performance liquid chromatography, and plasma 5-FU and uracil concentrations were determined using gas chromatography-mass spectrometry. National Institutes of Health Common Toxicity Criteria were used for assessment of toxicity.

RESULTS

The concentrations of FT, 5-FU, and uracil showed wide interpatient variations. Maximum plasma concentrations (Cp(max)) of all three compounds were achieved in 0.3 to 4.0 h. At the various study doses, the terminal half-life (t 1/2beta) of FT ranged from 3.9 to 5.9 h, the area under the concentration-versus-time curve (AUC0-6h) ranged from 16,220 to 52,446 (ng/ml)h, the total clearance (ClT) ranged from 100 to 175 ml/min, and the steady-state volume of distribution (Vd(ss)) ranged from 18.3 to 28.7 l. The 5-FU generated from FT had an apparent distribution half-life (t 1/2alpha) and an apparent elimination half-life (t 1/2beta) of 0.3-1.3 h and 4.9-7.0 h, respectively. The AUC0-6h of 5-FU ranged from 120 to 325 (ng/ml)h. Uracil had a t 1/2alpha of 0.2-0.5 h and the level quickly returned to the endogenous level. The AUC0-6h for uracil ranged from 605 to 3764 (ng/ml)h, the ClT ranged from 3225 to 7748 ml/min, and the Vd(ss) ranged from 341 to 1354 l. The Cp(max) and AUC0-6h of both FT and uracil were significantly correlated with FT doses (P-values of 0.0244 and 0.0112) and with uracil doses (P-values of 0.0346 and 0.0083), respectively. In addition to interpatient variations, intrapatient variations were also observed in six patients who had pharmacology studies done on days 1 and 26+/-2 at the same study dose. We found that the repeated treatment with UFT caused cumulative increases in the values of Cp(max), Ctrough, and AUC0-6h of FT and 5-FU. The major toxic effects observed were diarrhea and nausea and vomiting. The occurrence of these toxic effects correlated significantly with the Cp(max) and AUC0-6h of 5-FU.

CONCLUSIONS

The pharmacology studies showed that FT and uracil were readily absorbed orally and that FT was rapidly converted to 5-FU. The preliminary findings suggest that determination of plasma levels of 5-FU after oral administration of UFT may help predict subsequent toxic effects.

A binding site for the kringle II domain of prothrombin in the apple 1 domain of factor XI

Previously we defined binding sites for high molecular weight kininogen (HK) and thrombin in the Apple 1 (A1) domain of factor XI (FXI). Since prothrombin (and Ca(2+)) can bind FXI and can substitute for HK (and Zn(2+)) as a cofactor for FXI binding to platelets, we have attempted to identify a prothrombin-binding site in FXI. The recombinant A1 domain (rA1, Glu(1)-Ser(90)) inhibited the saturable, specific and reversible binding of prothrombin to FXI, whereas neither the rA2 domain (Ser(90)-Ala(181)), rA3 domain (Ala(181)-Val(271)), nor rA4 domain (Phe(272)-Glu(361)) inhibited prothrombin binding to FXI. Kinetic binding studies using surface plasmon resonance showed binding of FXI (K(d) approximately 71 nm) and the rA1 domain (K(d) approximately 239 nm) but not rA2, rA3, or rA4 to immobilized prothrombin. Reciprocal binding studies revealed that synthetic peptides (encompassing residues Ala(45)-Ser(86)) containing both HK- and thrombin-binding sites, inhibit (125)I-rA1 (Glu(1)-Ser(90)) binding to prothrombin, (125)I-prothrombin binding to FXI, and (125)I-prothrombin fragment 2 (Ser(156)-Arg(271)) binding to FXI. However, homologous prekallikrein-derived peptides (encompassing Pro(45)-Gly(86)) did not inhibit FXI rA1 binding to prothrombin. The peptides Ala(45)-Arg(54), Phe(56)-Val(71), and Asp(72)-Ser(86), derived from sequences of the A1 domain of FXI, acted synergistically to inhibit (125)I-rA1 binding to prothrombin. Mutant rA1 peptides (V64A and I77A), which did not inhibit FXI binding to HK, retained full capacity to inhibit rA1 domain binding to prothrombin, and mutant rA1 peptides Ala(45)-Ala(54) (D51A) and Val(59)-Arg(70) (E66A), which did not inhibit FXI binding to thrombin, retained full capacity to inhibit rA1 domain binding to prothrombin. Thus, these experiments demonstrate that a prothrombin binding site exists in the A1 domain of FXI spanning residues Ala(45)-Ser(86) that is contiguous with but separate and distinct from the HK- and thrombin-binding sites and that this interaction occurs through the kringle II domain of prothrombin.

The role of high molecular weight kininogen and prothrombin as cofactors in the binding of factor XI A3 domain to the platelet surface

We have reported that prothrombin (1 microm) is able to replace high molecular weight kininogen (45 nm) as a cofactor for the specific binding of factor XI to the platelet (Baglia, F. A., and Walsh, P. N. (1998) Biochemistry 37, 2271-2281). We have also determined that prothrombin fragment 2 binds to the Apple 1 domain of factor XI at or near the site where high molecular weight kininogen binds. A region of 31 amino acids derived from high molecular weight kininogen (HK31-mer) can also bind to factor XI (Tait, J. F., and Fujikawa, K. (1987) J. Biol. Chem. 262, 11651-11656). We therefore investigated the role of prothrombin fragment 2 and HK31-mer as cofactors in the binding of factor XI to activated platelets. Our experiments demonstrated that prothrombin fragment 2 (1 microm) or the HK31-mer (8 microm) are able to replace high molecular weight kininogen (45 nm) or prothrombin (1 microm) as cofactors for the binding of factor XI to the platelet. To localize the platelet binding site on factor XI, we used mutant full-length recombinant factor XI molecules in which the platelet binding site in the Apple 3 domain was altered by alanine scanning mutagenesis. The recombinant factor XI with alanine substitutions at positions Ser(248), Arg(250), Lys(255), Leu(257), Phe(260), or Gln(263) were defective in their ability to bind to activated platelets. Thus, the interaction of factor XI with platelets is mediated by the amino acid residues Ser(248), Arg(250), Lys(255), Leu(257), Phe(260), and Gln(263) within the Apple 3 domain.

Factor XI binding to activated platelets is mediated by residues R(250), K(255), F(260), and Q(263) within the apple 3 domain

To localize the platelet binding site on factor XI, rationally designed, conformationally constrained synthetic peptides were used to compete with [(125)I]factor XI binding to activated platelets. The major platelet binding energy resided within the sequence of amino acids T(249)-F(260). Homology scanning, using prekallikrein amino acid substitutions within the synthetic peptide T(249)-F(260), identified a major role for R(250) in platelet binding. Inhibition of [(125)I]factor XI binding to activated platelets by the recombinant Apple 3 domain of factor XI and inhibition by unlabeled factor XI were identical, whereas the recombinant Apple 3 domain of prekallikrein had little effect. A "gain-of-function" chimera in which the C-terminal amino acid sequence of the Apple 3 domain of prekallikrein was replaced with that of factor XI was as effective as the recombinant Apple 3 domain of factor XI and unlabeled factor XI in inhibiting [(125)I]factor XI binding to activated platelets. Alanine scanning mutagenic analysis of the recombinant Apple 3 domain of factor XI indicated that amino acids R(250), K(255), F(260), and Q(263) (but not K(252) or K(253)) are important for platelet binding. Thus, the binding energy mediating the interaction of factor XI with platelets is contained within the C-terminal amino acid sequence of the Apple 3 domain (T(249)-V(271)) and is mediated in part by amino acid residues R(250), K(255), F(260), and Q(263).

Susceptibility surveillance among gram-negative bacilli at a cancer center

We conducted a survey of susceptibility among 758 gram-negative bacilli (GNB; collected from cancer patients over a 3-month period) to commonly used antibiotics. The overall resistance among GNB was least for piperacillin/tazobactam and meropenem (5 and 6%, respectively) followed by cefepime (8%), imipenem (9%), amikacin (12%), ofloxacin (13%), ciprofloxacin, ceftazidime and ticarcillin/clavulanate (14% each), aztreonam (18%) and tobramycin (24%). In comparison to data on antibiotic resistance to ceftazidime, imipenem, ciprofloxacin and aztreonam in similar studies in 1985 and 1994, resistance has significantly increased to all four antibiotic classes. Based on our current study, meropenem, cefepime, imipenem and piperacillin/tazobactam would be the most appropriate choices in our institution for empiric therapy of GNB infections in febrile neutropenic patients.

Expression of ataxin-2 in brains from normal individuals and patients with Alzheimer's disease and spinocerebellar ataxia 2

Spinocerebellar ataxia type 2 (SCA2) is caused by expansion of a CAG trinucleotide repeat located in the coding region of the human SCA2 gene. The SCA2 gene product, ataxin-2, is a basic protein with two domains (Sm1 and Sm2) implicated in RNA splicing and protein interaction. However, the wild-type function of ataxin-2 is yet to be determined. To help clarify the function of ataxin-2, we produced antibodies to three antigenic peptides of ataxin-2 and analyzed the expression pattern of ataxin-2 in normal and SCA2 adult brains and cerebellum at different developmental stages. These studies revealed that (1) both wild-type and mutant forms of ataxin-2 were synthesized; (2) the wild-type ataxin-2 was localized in the cytoplasm in specific neuronal groups with strong labeling of Purkinje cells; (3) the level of ataxin-2 increased with age in Purkinje cells of normal individuals; and (4) ataxin-2-like immunoreactivity in SCA2 brain tissues was more intense than in normal brain tissues, and intranuclear ubiquitinated inclusions were not seen in SCA2 brain tissues.

Comparison of 5-fluorouracil pharmacokinetics in patients receiving continuous 5-fluorouracil infusion and oral uracil plus N1-(2'-tetrahydrofuryl)-5-fluorouracil

Plasma 5-fluorouracil (5-FU) levels were compared in the same patients after approximately equimolar doses (1.9 mmol/ m2/day) of 5-day continuous i.v. infusion of 5-FU (CIFU) and oral administration of a formulation of two combined pharmacological agents, uracil (U) plus N1-(2'-tetrahydrofuryl)-5-fluorouracil (ftorafur or FT), a prodrug of 5-FU. Ten patients received CIFU for 5 days, then, after a week wash-out period, began the 28-day oral UFT regimen, which was given in three daily divided doses. Following 1 h of CIFU, the plasma 5-FU levels reached a steady state of 0.6+/-0.2 microM (mean+/-SD; day 1), which was maintained for the entire 5-day infusion period (0.6+/-0.1 microM). In contrast, the maximum 5-FU concentrations (Cpmax) generated from oral UFT at 1 h after dose administration on days 1 and 5 were 2.1+/-1.5 microM and 2.3+/-1.9 microM, respectively, which were higher than the steady-state levels during CIFU. These high 5-FU levels disappeared with an apparent elimination half-life (tl/2,beta) of 5.2+/-2.4 h (day 1) and 7.2+/-3.9 h (day 5). On day 1 of both regimens, CIFU patients had significantly larger 5-FU area under the concentration versus time curve (AUC0-8h) values (4.4+/-1.3 microM.h) than the AUC value when they received the UFT regimen (2.6+/-1.7 microM.h; P = 0.02). However, by day 5, there were no significant differences between AUC0-8 h values in patients receiving CIFU and UFT, respectively (4.8+/-1.5 microM.h versus 3.8+/-2.2 microM.h; P = 0.30)]. On day 5, the average concentration of the metabolite 5-FU at steady-state (Css,aver) within dose interval of 8 h (0.48+/-0.28 microM) for the oral UFT treatment is comparable with the Cpss values of 5-FU from CIFU-treated patients. The post-UFT generated 5-FU pharmacokinetic parameters (higher Cp(mx, comparable Css,aver, equal AUC values, and longer apparent t1/2,beta of 5-FU) may make oral UFT a preferred method of delivering this fluoropyrimidine over CIFU. In addition, oral UFT would eliminate the incidence of venous thrombosis and catheter-related infections sometimes seen in patients treated with CIFU. Furthermore, the convenience and decreased cost of oral administration may be preferable for many patients, particularly those receiving 5-FU for palliation.

A binding site for heparin in the apple 3 domain of factor XI

Since heparin potentiates activated factor XI (FXIa) inhibition by protease nexin-2 by providing a template to which both proteins bind (Zhang, Y., Scandura, J. M., Van Nostrand, W. E., and Walsh, P. N. (1997) J. Biol. Chem. 272, 26139-26144), we examined binding of factor XI (FXI) and FXIa to heparin. FXIa binds to heparin (Kd approximately 0.7 x 10(-9) M) >150-fold more tightly than FXI (Kd approximately 1.1 x 10(-7) M). To localize the heparin-binding site on FXI, rationally designed conformationally constrained synthetic peptides were used to compete with 125I-FXI binding to heparin. A peptide derived from the Apple 3 (A3) domain of FXI (Asn235-Arg266) inhibited FXI binding to heparin (Kd approximately 3.4 x 10(-6) M), whereas peptides from the A1 domain (Phe56-Ser86), A2 domain (Ala134-Ala176), and A4 domain (Ala317-Gly350) had no such effect. The recombinant A3 domain (rA3, Ala181-Val271) inhibited FXI binding to heparin (Ki approximately 1.4 x 10(-7) M) indicating that all the information necessary for FXI binding to heparin is contained entirely within the A3 domain. The A3 domain also contains a platelet-binding site (Asn235-Arg266), consisting of three surface-exposed loop structures, Pro229-Gln233, Thr741-Leu246, and Thr249-Phe260 (Baglia, F. A., Jameson, B. A., and Walsh, P. N. (1995) J. Biol. Chem. 270, 6734-6740). Only peptide Thr249-Phe260 (which contains a heparin binding consensus sequence, RIKKSKA) inhibits FXI binding to heparin (Ki = 2.1 x 10(-7) M), whereas peptides Pro229-Gln233 and Thr241- Leu246 had no effect. Fine mapping of the heparin-binding site using prekallikrein analogue amino acid substitutions of the synthetic peptide Thr249-Phe260 and alanine scanning of the recombinant A3 indicated that the amino acids Lys252 and Lys253 are important for heparin binding. Thus, the sequence Thr249-Phe260 which contains most of the binding energy for FXI interaction with platelets also mediates the binding of FXI to heparin.

Phase I trial of uracil-tegafur (UFT) plus oral leucovorin: 28-day schedule

UFT [Taiho Pharmaceutical Co. Ltd., Tokyo, Japan; (BMS-200604), Bristol-Myers Squibb, Princeton, NJ], a fluorouracil prodrug, is an oral 4:1 molar concentration of uracil plus tegafur. This study examined the dose-limiting toxic effects and maximum tolerated dose of UFT plus leucovorin administered for 28 consecutive days followed by a 7-day rest period. A course of therapy was repeated every 35 days. UFT dose levels examined were 200 mg/m2/day, with planned escalations to 250, 300, 350, and 400 mg/m2/day; the leucovorin dose remained at 150 mg/day. Three patients were initially enrolled at each UFT dose level. The total daily doses of both UFT and leucovorin were divided into three doses administered every 8 hr. Diarrhea became the dose-limiting toxicity at 400 mg/m2/day UFT, with grade 3 diarrhea noted in 2 of the 3 patients receiving that dose. To further define a phase II UFT starting dose, 3 additional patients were entered at the 350 mg/m2 level; 3 of the 6 patients treated at this level developed grade 3 nonhematological toxic effects. No partial or complete responses were observed. The recommended phase II UFT starting dose is 300 mg/m2/day plus 150 mg/day leucovorin. Since neutropenia, significant mucositis, and "hand-foot syndrome" were not observed with UFT plus leucovorin, the toxicity profile of this regimen appears favorable compared with that of intravenous regimens of fluorouracil plus leucovorin. This phase I trial of UFT served as the basis for a phase II trial, current phase III trials, and a national adjuvant therapy trial of UFT for high-risk colon cancer patients.

Neuronal expression and intracellular localization of presenilins in normal and Alzheimer disease brains

The expression patterns of presenilin 1 (PS1) and presenilin 2 (PS2) in human normal and Alzheimer disease (AD) brains were investigated using antibodies to specific N-terminal peptides of PS1 (Alzh14A and Alzh14B) and PS2 (Alzh1A-AB). The antibodies to peptides Alzh14A (Alzh14A-AB) and Alzh14B (Alzh14B-AB) detected the full-length protein (approximately 63 kDa) and the N-terminal-processed fragment (36 kDa) of PS1, while the Alzh1A-AB detected mainly the N-terminal-processed fragment (36 kDa) of PS2. Immunofluorescent staining detected by confocal microscopy suggested that both native PS1 and PS2 are localized mainly in the Golgi/ER apparatus. Immunohistochemical studies of human temporal lobes from 2 normal and 5 sporadic Alzheimer brains revealed high levels of PS1 and PS2 expression in the granule cell layer and pyramidal neurons of the hippocampus. Strong immunoreactivity was found in reactive astrocytes and neurofibrillary tangles of all 5 Alzheimer brains. In contrast, only 2 sporadic Alzheimer brains showed presenilin-positive neuritic plaques. These observations suggest that presenilins may be involved in the pathology of some cases of sporadic AD.

In-vitro activity of trovafloxacin against clinical bacterial isolates from patients with cancer

The antibacterial activity of trovafloxacin was compared with that of ciprofloxacin, levofloxacin, ofloxacin, sparfloxacin and norfloxacin against bacterial isolates from patients with cancer. In general, the activity of trovafloxacin was comparable to that of ciprofloxacin, levofloxacin and sparfloxacin against most Gram-negative isolates tested (minor differences in the activity of each agent against individual species were seen) and it was the most active agent tested against Stenotrophomonas maltophilia, inhibiting 80% of these isolates at <2.0 mg/L. Trovafloxacin was also the most active agent tested against Gram-positive organisms, including ciprofloxacin-susceptible strains and most ciprofloxacin- and methicillin-resistant staphylococci and enterococci. It was much more active than ciprofloxacin against streptococci, including Streptococcus pneumoniae and the viridans streptococci, and was also active against Bacillus cereus and Listeria monocytogenes, inhibiting all isolates at a concentration of <0.5 mg/L.

Phase I trial of uracil-tegafur (UFT) plus oral leucovorin: 14-day schedule

We previously reported results of a Phase II trial of UFT [Taiho Pharmaceutical Ltd., Tokyo, Japan; (BMS-200604) Bristol-Myers Squibb, Princeton, NJ], an oral 4:1 molar concentration of uracil and tegafur, plus oral leucovorin for metastatic colorectal carcinoma (Pazdur et al., J. Clin. Oncol. 12:2296-2300, 1994]. Our results demonstrated that a 28-day schedule of this combination produced a response rate similar to that obtained with conventional intravenous fluorouracil (5-FU)-plus-leucovorin regimens but without the severe or life-threatening neutropenia or oral mucositis that complicates intravenous 5-FU regimens. The current Phase I trial examines the dose-limiting toxic effects and maximum tolerated dose of a 14-consecutive-day schedule of UFT plus oral leucovorin in 14 patients who had histologically proven cancer and had received prior chemotherapy. The daily UFT plus leucovorin dose was divided into three doses administered orally every 8 hours. In this study, the UFT dose was escalated while the leucovorin dose remained at 150 mg/day. Of the 14 patients, 4 were initially treated at the 350-mg/m2/day UFT level for 14 days without any dose-limiting toxic reactions. Subsequently, another 7 patients were treated at the 400-mg/m2/day level; grade 3 diarrhea developed in 3 of these 7 (with severe abdominal cramping in 2 cases and severe nausea and vomiting unresponsive to antiemetics in the third). To better define the starting dose for phase II studies, an additional 3 patients were treated at the 350-mg/m2/day dose level. Of the total 7 patients treated at 350 mg/m2/day, grade 3 toxic events (diarrhea) developed in 2 patients. Grade 1-2 toxic effects noted at this level included fatigue, stomatitis, skin rash, abdominal pain, nausea, and vomiting. Neither partial nor complete responses were observed in this trial. The maximum tolerated dose of this schedule is 350 mg/m2/day UFT plus 150 mg/day oral leucovorin. However, because of this schedule's inferior dose intensity compared with that of the 28-day schedule of UFT plus leucovorin, subsequent development of UFT in the United States has focused on the 28-day regimen.

Phase I trials of uracil-tegafur (UFT) using 5 and 28 day administration schedules: demonstration of schedule-dependent toxicities

We conducted two consecutive phase I clinical trials to identify the qualitative and quantitative toxic effects of uracil-tegafur (UFT) [Taiho Pharmaceutical Co. Ltd, Tokyo, Japan; (BMS-200604) Bristol-Myers Squibb, Princeton, NJ] administered either on a 5 or 28 day schedule and to determine the phase II trial starting doses for both schedules. Nineteen patients were entered in the 5 day schedule and 23 patients were entered on the 28 day schedule; a minimum of three patients were entered at each dose level studied. In both phase I trials, the daily UFT dose was divided into three doses administered every 8 h. Dose levels examined with the 5 day schedule were 360, 720, 900 and subsequent de-escalation to 800 mg/m2/day. Dose levels studied with the 28 day schedule were 180, 360, 450 and subsequent de-escalation to 400 mg/m2/day. With the 5 day schedule, the dose-limiting toxicity (DLT) was granulocytopenia, with four of five patients experiencing grade 4 granulocytopenia at the 900 mg/m2/day dose level. With the 28 day schedule, the DLT was diarrhea, which was noted in three of eight patients treated at 400 mg/m2/day and in three of six patients treated at 450 mg/m2/day. At these dose levels, four of these patients required prolonged hospitalizations for their diarrhea. The toxic effects of UFT are schedule dependent, with marked differences in the toxic effect profile (neutropenia versus diarrhea). With the 5 day schedule, the phase II UFT starting dose is 800 mg/m2/day. On the 28 day schedule, the suggested phase II UFT starting dose is 360 mg/m2/day. Future clinical trials examining the combination the UFT plus oral folinic acid are being conducted to develop oral regimens of therapy for advanced colorectal carcinoma and adjuvant therapy for colon carcinoma.

Survey of antibiotic susceptibility among gram-negative bacilli at a cancer center

A survey of the susceptibility of gram-negative bacilli isolated from cancer patients to broad-spectrum antimicrobial agents was conducted. The organisms were isolated from all patient specimens submitted to the microbiology laboratory during a 3-month study period. Overall, the least resistance was observed against cefoperazone/sulbactam, ciprofloxacin, and imipenem. Of these, cefoperazone/sulbactam has had limited usage at our institution. Drugs used more frequently (piperacillin, aztreonam, cefoperazone, ceftazidime) were associated with greater levels of resistance. Imipenem and ciprofloxacin have enjoyed wide usage but the level of resistance remains low.

In-vitro activity of ramoplanin (a novel lipoglycopeptide), vancomycin, and teicoplanin against gram-positive clinical isolates from cancer patients

The in-vitro activities of ramoplanin, vancomycin, and teicoplanin against Gram-positive organisms isolated from cancer patients were determined. Ramoplanin was the most active agent tested inhibiting all isolates at a concentration of < or = 0.5 mg/L. Although all isolates were also susceptible to vancomycin and teicoplanin, their activities were surpassed by that of ramoplanin. The activity of teicoplanin was moderately better than that of vancomycin against Bacillus cereus, Enterococcus faecium, Listeria monocytogenes, methicillin-resistant Staphylococcus aureus, and most streptococcal isolates, and was comparable to vancomycin for the remainder of the isolates tested.

A phase I and pharmacokinetic study of oral uracil, ftorafur, and leucovorin in patients with advanced cancer

A phase I and pharmacokinetics study of oral uracil, ftorafur, and leucovorin was performed in patients with advanced cancer. Uracil plus ftorafur (UFT) was given in a 4:1 molar ratio in three divided doses for 28 consecutive days. Patient cohorts were treated at 200, 250, 300, and 350 mg/m2 of UFT daily. For all patients, 150 mg of leucovorin was given daily in three oral doses. A 1-week rest period followed each 28-day treatment course. Gastrointestinal toxicity, characterized by diarrhea, nausea, and vomiting, was dose-limiting at 350 mg/m2 UFT in patients who had received prior chemotherapy. Mild fatigue and transient hyperbilirubinemia were also common. In previously untreated patients, UFT at 350 mg/m2 was well-tolerated, suggesting this as an acceptable phase II dose in this schedule with leucovorin. Two of eight previously untreated patients with advanced colorectal cancer had partial responses with UFT (350 mg/m2) plus leucovorin. Pharmacokinetic parameters [ftorafur, uracil, 5-fluorouracil (5-FU), 5-methyltetrahydrofolate] showed wide interpatient variations. Plasma levels of 5-FU (Cmax 1.4 +/- 1.9 microM) were comparable to those achieved with protracted venous infusions, and folate levels (Cmax 6.1 +/- 3.6 microM) were sufficient for biochemical modulation. Ongoing study will determine if this convenient oral regimen will compare favorably in terms of efficacy, toxicity, and cost with intravenous fluoropyrimidine programs.

Normocalcemic effect of gallium nitrate in a hypercalcemic rat model

An established rat hypercalcemia model was used to study the effects of gallium nitrate on elevated serum calcium levels. Gallium nitrate was administered by i.v. or i.p. injection at daily doses of 0.07-0.45 mmol/kg for 5 days to the hypercalcemic rats beginning 1 day following surgery. A dose-correlated normocalcemic response was observed. Gallium nitrate administered late after the induction of the hypercalcemic state was also effective in reducing serum calcium levels. The p.o. administration, however, even at doses as high as 0.45 mmol/kg, did not reduce serum calcium to normal levels. The values of area under the concentration versus time curve (0-24 h) of gallium in normal rats were comparable after i.v. [49.2 (micrograms/ml)h] or i.p. [57.0 (micrograms/ml)h] injections. In contrast, the p.o. route achieved only 15% bioavailability, which may explain the ineffectiveness of p.o. administered gallium nitrate at that dose level. This study suggests that daily i.v. bolus injections of gallium nitrate for managing hypercalcemia may be potentially as effective as the current regimen of continuous i.v. infusion.

In vitro activity of FK-037, a novel parenteral cephalosporin, against bacterial isolates from neutropenic cancer patients

The in vitro activity of FK-037, a novel parenteral cephalosporin, was compared to that of ceftazidime, aztreonam and piperacillin (agents often used in empiric regimens in cancer patients) against recent bacterial isolates from patients with cancer. FK-037 was either equal to or 2 to 16-fold more active than the comparative agents against members of the Enterobacteriaceae. It was also active against Acinetobacter spp., Aeromonas spp., Pseudomonas aeruginosa, and other Pseudomonas spp. Xanthomonas maltophilia and Alcaligenes denitrificans were relatively resistant to all four agents. FK-037 was also 4 to 16-fold more active against most gram-positive organisms (including some methicillin-resistant staphylococci) than was ceftazidime. Enterococcus spp., Listeria monocytogenes and Staphylococcus haemolyticus were relatively resistant to FK-037 and ceftazidime. Overall, FK-037 has a broad antimicrobial spectrum that includes the majority of gram-positive and gram-negative isolates.

Susceptibilities of bacterial isolates from patients with cancer to levofloxacin and other quinolones

The antibacterial activity of levofloxacin was compared with those of ofloxacin and ciprofloxacin against bacterial isolates from patients with cancer. In general, levofloxacin was as active or was twofold more active than ofloxacin and was two- to fourfold less active than ciprofloxacin against most gram-negative pathogens. Against Pseudomonas aeruginosa, ciprofloxacin was the most active agent tested (MIC for 90% of isolates tested, 1.0 microgram/ml). Overall, all three agents had similar activities against gram-positive organisms and were moderately active against methicillin-susceptible Staphylococcus aureus and coagulase-negative staphylococci, Streptococcus species, and Enterococcus species.

Determination of peplomycin in mouse tissues and biofluids by radioimmunoassay

Peplomycin, an antitumour antibiotic analogue of bleomycin, was measured in mouse tissues using a rapid radioimmunoassay. Antiserum, obtained by immunizing rabbits with peplomycin-bovine serum albumin conjugate, showed no significant cross-reactivity with the closely related peplomycin analogues bleomycin and liblomycin, nor with a number of other structurally unrelated antitumour drugs. The assay is sensitive and can detect peplomycin levels as low as 2 ng ml-1. The relative intra- and inter-assay standard deviation is < or = 5%, indicating good assay reproducibility. Peplomycin levels in mouse tissues were easily determined without extraction. Fifteen minutes after administration of a single intraperitoneal dose of peplomycin at 8.5 mg kg-1 (1/10 of LD50), high drug levels were found in plasma (46 micrograms ml-1), kidneys (38 micrograms g-1), urine and bladder (32 micrograms ml-1), followed by gastrointestinal tract (13 micrograms g-1), lung (8 micrograms g-1), spleen (3.7 micrograms g-1), heart (3.6 micrograms g-1), gall bladder (2.7 micrograms g-1), liver (2 micrograms g-1), and brain (0.6 microgram g-1). The total amount of drug in all these organs accounted for more than 80% of the dose administered. We conclude that the radioimmunoassay is sensitive and reproducible and is an ideal tool for measuring peplomycin in tissues and biofluids for pharmacological studies.

In vitro activities of antimicrobial agents against clinical isolates of Flavimonas oryzihabitans obtained from patients with cancer

We evaluated the in vitro activities of 21 different antimicrobial agents against nine clinical isolates of Flavimonas oryzihabitans obtained from patients with cancer. The organisms were susceptible to most agents commonly used for the empiric therapy (aminoglycosides, ureidopenicillins, extended-spectrum cephalosporins, monobactams, and carbapenems) and prevention of infections (quinolones and trimethoprim-sulfamethoxazole) in this patient population.

Clinical pharmacology of 11-acetyl-8-carbamoyloxymethyl-4-formyl-14-oxa-1,11-diazatetracyclo (7.4.1.0(2,7).0(10,12) tetradeca-2,4,6-trien-6,9-diyl diacetate (FK 973)

FK 973, a novel substituted dihydrobenzoxazine structurally similar to mitomycin C, is a derivative of the product isolated from Streptomyces sandaensis. In vitro and in rodents, it is a potent antitumor agent. During Phase I clinical trials, we evaluated the pharmacologic properties of FK 973 in eight adenocarcinoma patients after a 30-min i.v. infusion of doses ranging from 7 to 45mg/m2. An established enzyme immunoassay that measures the stable deacetylated active metabolite FR66980 showed that the plasma drug levels declined biphasically with a terminal half life (t1/2 beta) of 4.7 +/- 1.6hr (mean +/- S.D.) The total clearance rate was 438 +/- 113ml/(min/m2). Both the maximum plasma drug concentrations (Cmax) and the area under the concentration-versus-time curve (AUC) were dose related. In addition to nausea and vomiting, alopecia, and myelosuppression, three patients experienced a delayed vascular-leak syndrome. The 3 patients had received doses among the highest studied, and the toxicity appeared to be dose related and cumulative. The evidence suggests that higher doses generated higher Cmax and AUC values, which may be correlated with toxic effects.

L-asparaginase and PEG asparaginase--past, present, and future

L-asparaginase is an enzyme which hydrolyses asparagine. Since the 1960s it has been known that some leukemic cells are deficient in asparagine synthetase and therefore cannot manufacture sufficient quantities of this essential amino acid to maintain cell viability. L-asparaginase is predominantly useful in acute lymphocytic leukemia (ALL) although responses have been noted in patients with acute myeloid leukemia, lymphoma, and rarely other tumors. L-asparaginase has been used in conjunction with methotrexate and ara-C in combination programs in leukemia. The major side-effect limiting the usefulness of L-asparaginase is allergic reactions. In addition, it is probable that neutralizing antibodies develop which shorten the half life of the drug so that the goal of depletion of plasma levels of asparagine cannot be attained or maintained. Polyethylene glycol (M.W. 5000) can be conjugated to L-asparaginase at sites not involving the active site of the enzyme. This enables free access of a small molecule, asparagine, to the active site of the enzyme but prevents uptake by the reticuloendothelial system, greatly decreasing the probability of developing antibodies against the asparaginase and prolongs the circulating half life of the drug. In a phase I/II study conducted at the M.D. Anderson Cancer Center, 37 heavily pretreated patients with refractory hematologic malignancy were treated. The age range from 15 to 73 years, median 49 years. Nineteen patients had ALL, 15 lymphoma, two myeloma, and one Hodgkin's disease. The dose levels of PEG L-asparaginase varied from 250 IU/m2 up to 8000 IU/m2. The pharmacokinetic profile demonstrated a monophasic half life consistent with a one compartment model with a single elimination phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Depletion of patients' plasma tryptophan using tryptophan side-chain oxidase columns

The use of the enzyme tryptophan side-chain oxidase, isolated from Pseudomonas XA, was explored in 3 patients with refractory acute lymphocytic leukemia. Patients were given either a low-tryptophan diet or tryptophan-free hyperalimentation, prior to and during therapy. Their plasma, separated by pheresis, was continuously passed through a tryptophan depletion column containing the immobilized tryptophan side-chain oxidase. Up to 4 plasma volumes were passed through the column daily, 5 days per week for 2-3 weeks, and plasma tryptophan levels, both free and total, were measured by high-performance liquid chromatography. Pre- and postcolumn plasma samples were collected throughout the pheresis procedure. All postcolumn plasma samples had unmeasurable tryptophan levels throughout the treatment period, whereas precolumn samples were always measurable. Generally, tryptophan levels of plasma isolated from peripheral blood decreased after therapy, but rebounded by the next day. The enzyme depletion column reduces circulating plasma tryptophan levels, and its use is well tolerated by patients. However, further development of this method will require study of the effects of diet and of the duration, interval, and frequency of use of this column on therapeutic efficacy. Problems include difficulties with extended diet compliance and apparently intensive mobilization of tryptophan from body stores, which may preclude the clinical application of this enzyme depletion column.

Clinical pharmacology of combined oral uracil and ftorafur

Phase I clinical trials of the combination of oral uracil with ftorafur (Ft) were conducted in patients with solid tumors over either a 5-day (345 mg/m2/day) or a 28-day (160 mg/m2/day) period. The uracil dose, which was four times the Ft dose (molar basis), was previously shown to be optimal at inhibiting the degradation of 5-fluorouracil (5-FU). Pharmacology was performed on the first dose of the first day of therapy. Ft was measured by HPLC, whereas uracil and 5-FU were measured using GC/MS. Plasma levels were highest for Ft, followed by uracil and 5-FU at all time points. Peak and trough levels after selected subsequent doses were also measured; these varied in the individual from day to day. Maximum plasma levels (Cpmax) for Ft, uracil, and 5-FU except in one patient were achieved at 0.6-2.1 hr, 0.6-4.1 hr, and 0.7-2.0 hr, respectively. Generally, lower doses yielded more rapid decay of 5-FU and uracil levels than did higher doses. No correlation was observed between myelotoxicities (granulocytopenia and leukopenia) and the Cpmax and AUC0-6hr of Ft (p > 0.2). However, after the highest uracil and Ft dose (approximately 300 mg/m2/Ft study dose), the Cpmax and AUC0-6hr values of 5-FU revealed significant differences (p < 0.05) in three patients each with and without myelotoxicity. These associations were similarly observed with uracil. Our findings thus indicate that measuring plasma uracil and more importantly, the 5-FU levels, may predict hematological toxicity and enable subsequent dose adjustments.

Determination of plicamycin in plasma by radioimmunoassay

This article describes a method for the determination of plicamycin in plasma by radioimmunoassay. The anti-plicamycin antibody was produced against a plicamycin-bovine serum albumin conjugate prepared by using diazotized p-aminobenzoic acid as a cross-linker. The radiolabeled ligand, 125I-plicamycin, was prepared by the chloramine-T method. The linear plicamycin concentration range was 7-400 ng/ml. The coefficients of variation for intra- and interday variabilities were 7.5 and 15%, respectively. No interference was observed from either the structurally related chromomycin A or concomitantly used drugs hydroxyurea or allopurinol. With this method of testing, plicamycin levels in plasma could be determined in patients receiving small (0.85-1.0 mg/m2) therapeutic plicamycin doses. Preliminary pharmacokinetic data in humans indicate that the plasma drug disappearance curve was biphasic with a mean elimination half-life of 10.6 +/- 1.7 h, total clearance rate of 11.1 +/- 0.4 ml/min/m2, and area under the plasma drug concentration-time curve of 1,289-1,546 ng-h/ml. This assay method is clinically useful for pharmacokinetic studies of plicamycin and may be helpful in the design of rational therapeutic drug trials.

In vitro activity of Ro 23-9424, a dual-action antibacterial agent, against bacterial isolates from cancer patients compared with those of other agents

The in vitro activity of Ro 23-9424 against bacterial isolates from patients with cancer was compared with those of fleroxacin, ciprofloxacin, cefoperazone, and ceftazidime. Ro 23-9424 inhibited the majority of the members of the family Enterobacteriaceae and all Aeromonas isolates at a concentration of less than or equal to 1.0 micrograms/ml. It was also active against Acinetobacter spp. and Haemophilus influenzae, including beta-lactamase-producing strains. The MIC for 90% of isolates (MIC90) of Pseudomonas aeruginosa was 16.0 micrograms/ml. All group A and B streptococci were inhibited by less than or equal to 0.25 micrograms/ml, and 90% of group G streptococci and Streptococcus pneumoniae were inhibited by 1.0 micrograms/ml. All methicillin-susceptible strains of Staphylococcus aureus and 60% of methicillin-resistant strains were susceptible to 2.0 micrograms of Ro 23-9424 per ml, whereas the MIC90 for Staphylococcus epidermidis and Staphylococcus hominis isolates was 4.0 micrograms/ml. Staphylococcus haemolyticus and Enterococcus spp. were less susceptible; MIC90s for them were 16.0 and 32.0 micrograms/ml. Ro 23-9424 has a broad antibacterial spectrum and potential utility for therapy of infections in cancer patients.

Phase I trial of FK973: description of a delayed vascular leak syndrome

FK973 is a novel, substituted dihydrobenzoxazine structurally similar to mitomycin. FK973 lacks cross-resistance with mitomycin, doxorubicin, and vincristine in murine tumor models. A phase I study of FK973 was initiated using a 30-minute infusion repeated every 4 weeks. Of 17 patients enrolled on the study, a minimum of three patients were entered at each dose level: 7, 14, 21, 30, and 45 mg/m2. The dose-limiting toxicity was a vascular leak syndrome (VLS) characterized by pericardial and pleural effusions, ascites, and subcutaneous edema. These conditions were observed in two patients treated with a dose of 30 mg/m2 and in four who received 45 mg/m2. VLS was observed 2 weeks after the third dose of 30 mg/m2 and one week after the second dose of 45 mg/m2. Of nine patients treated with a cumulative dose greater than 60 mg/m2, five experienced this toxic reaction. Reversible drug-related pneumonitis was noted in one patient after the third course of 30 mg/m2. Moderate nausea and vomiting were initially observed at a dose of 14 mg/m2 and alopecia at 30 mg/m2. Grade 3-4 granulocytopenia was observed in two patients treated with 45 mg/m2. Extensive myocardial degeneration was observed at autopsy in a patient who had received three courses of 30 mg/m2. One patient with metastatic colon carcinoma and another with metastatic pancreatic carcinoma experienced partial clinical responses. Although the drug's clinical activity appears promising, additional investigation is needed into the mechanism of toxicity prior to further clinical development.

Clinical pharmacology of 1-beta-D-arabinofuranosyl-5-azacytosine (fazarabine) following 72-hour infusion

The clinical pharmacology of fazarabine (1-beta-D-arabinofuranosyl-5-azacytosine), a structural analogue of 1-beta-D-arabinofuranosylcytosine (ara-C) and 5-azacytidine, was assessed in 14 patients with various malignancies during a phase I trial. Since the starting dose for the protocol was low (0.2 mg/m2/hr over a 72-hr continuous iv infusion), a radioimmunoassay (RIA) using commercially available ara-C antibody and [3H]ara-C was developed to measure the anticipated low plasma drug levels. The assay could be used to measure fazarabine accurately in plasma and urine with a sensitivity of 0.08 ng/ml. The RIA does not require extraction of samples. Using both RIA and HPLC, similar results were obtained in plasma samples from a patient receiving a high dose (180 mg/m2/hr) of fazarabine. The assay is simple, sensitive, reproducible, and specific. Following the infusion, plasma levels declined triphasically with a terminal half-life of 5.7 +/- 2.0 hr. The AUC was linearly related to dose. When the various doses were normalized to 1.75 mg/m2/hr (the maximum tolerated dose as determined from the phase I trial) the mean AUC value was 4232 +/- 987 (ng/ml)hr. Plasma steady-state drug levels (CPss) were achieved in 2-4 hr and were linearly dependent to dose. Also, when normalized, the mean CPss was 58 +/- 13 ng/ml, which is within the reported concentration range necessary for inhibiting malignant cell growth. Total clearance was rapid, 528 +/- 138 ml/(m2.min), and not dose-related.

In vitro activity of sparfloxacin (CI-978; AT-4140) against clinical isolates from cancer patients

The in vitro activity of sparfloxacin, a new quinolone, was compared with those of ciprofloxacin and fleroxacin against gram-positive and gram-negative bacteria, greater than 90% of which were isolated from blood culture specimens of cancer patients. Sparfloxacin was extremely active against Acinetobacter species, Aeromonas hydrophila, Citrobacter diversus, Enterobacter species, Escherichia coli, Klebsiella species, Proteus vulgaris, and Serratia marcescens (inhibiting greater than 90% of these isolates at a concentration of 0.5 microgram/ml) and moderately active against Pseudomonas species, other Proteus species, and Citrobacter freundii. Sparfloxacin inhibited greater than 90% of staphylococci (including methicillin-resistant and coagulase-negative strains) at a concentration of 0.12 microgram/ml and greater than 90% of streptococci (including Streptococcus pneumoniae) at a concentration of 1.0 microgram/ml. It was also active against Bacillus cereus, Enterococcus species, and Corynebacterium jeikeium, organisms that have become fairly common in cancer patients.

Comparative in vitro activities of newer quinolones against Pseudomonas species and Xanthomonas maltophilia isolated from patients with cancer

The in vitro susceptibilities of three Pseudomonas species (Pseudomonas aeruginosa, Pseudomonas putida, and Pseudomonas fluorescens) and Xanthomonas maltophilia to quinolone antimicrobial agents were determined. Several newer agents, particularly PD117558, PD117596, PD127391, sparfloxacin (AT-4140), A-56620, and temafloxacin, were active against Pseudomonas species. X. maltophilia isolates were generally less susceptible than were Pseudomonas isolates but were inhibited by some of the newer quinolones.

In-vitro activity of PD 117 596, a new quinolone, against bacterial isolates from cancer patients

The in-vitro activity of PD117 596, a new 4-quinolone antimicrobial agent was compared with that of ciprofloxacin against 798 Gram-positive and Gram-negative distinct isolates from cancer patients. PD117 596 was found to have a broad antimicrobial spectrum with excellent activity against the Enterobacteriaceae (MIC90 0.03 mg/l) Acinetobacter spp. (MIC90 0.25 mg/l), Aeromonas spp. (MIC100 0.06 mg/l) and Pseudomonas spp. including Ps. aeruginosa (MIC90 0.5 mg/l). It was also extremely active against Gram-positive micro-organisms particularly Staphylococcus spp. (including methicillin-resistant and coagulase-negative isolates) Bacillus spp. and streptococci. PD117 596 had lower minimal inhibitory concentrations against most isolates tested than ciprofloxacin, the most active currently available 4-quinolone.

[Activities of enzymes converting 5-fluorouracil to 5-fluorouridine-5' monophosphate and 5-fluorodeoxyuridine-5' monophosphate in subcultured cell lines and solid tumor tissues]

The activities of five enzymes, orotate phosphoribosyltransferase (OPRTase), uridine kinase (UR kinase), thymidine kinase (TdR kinase), uridine phosphorylase (UR Prylase) and thymidine phosphorylase (TdR Prylase), were examined in subcultured human acute leukemia cell lines (HL-60, CCRF-CEM), subcultured human solid tumor cell lines (Colo-205, HeLa-S3) and human cancerous tissues with a view to compare the activation of 5-fluorouracil in them. There was no significant difference in the activity of any enzyme between HL-60 and CCRF-CEM, Colo-205 and HeLa-S3, and human lung cancerous tissue and human colon cancerous tissue. Compared between the acute leukemia cell lines and the solid tumor cell lines, the UR kinase activity was high in both cell lines. The OPRTase and UR Prylase activities were low in the solid tumor cell lines. In the cancerous tissues, both the UR kinase and TdR kinase activities were low, but the UR Prylase and TdR Prylase activities were markedly high. The results suggest that the intracellular activation of 5-fluorouracil varies with different human cancerous cells. When the anti-cancer activity of 5-fluorouracil is tested in vitro, the difference of fluoropyrimidine metabolism in subcultured cell lines from that in the cancerous tissue should be taken in account.

Enzymatic conversion of 5-fluoro-2'-deoxyuridine to 5-fluorouracil or 5-fluoro-2'-deoxyuridine 5'-monophosphate in human tissues

The relative activities and Km values of pyrimidine nucleoside phosphorylase (PNPase) and thymidine (TdR) kinase were compared in postsurgical human tissues. TdR kinase, which activates 5-fluoro-2'-deoxyuridine (FUdR), was higher in normal liver than in other tissues examined. PNPase, which cleaves FUdR, was higher in normal spleen and liver and lowest in kidney. In normal lung tissue, almost all of the FUdR was cleaved at a high concentration since PNPase activity was much higher than TdR kinase activity. The affinity of TdR kinase as indicated by Km was greater in normal than in cancerous lung tissue. At a low concentration, FUdR is relatively well activated in the normal tissue; thus it may not be suitable for chemotherapy of lung cancer. When comparing normal versus cancerous colon tissues, no difference was seen in either TdR kinase affinities or TdR kinase and PNPase activities. However, the PNPase affinity for FUdR was significantly higher in normal than in cancerous colon tissue. When FUdR is maintained at low concentrations, it might have a selective cytotoxicity for colon cancer tissue since it is well cleaved in normal colon.

Comparative in vitro activity of the new erythromycin derivative dirithromycin against gram-positive bacteria isolated from cancer patients

The in vitro activity of dirithromycin (LY-237216), a new macrolide erythromycin derivative, was compared to that of four other agents (clarithromycin, erythromycin, roxithromycin, clindamycin) against 334 gram-positive isolates obtained from cancer patients. Dirithromycin was similar in potency and antimicrobial spectrum to the other agents tested. It was very active against beta-haemolytic streptococci and Streptococcus pneumoniae, and moderately active against penicillin and methicillin susceptible Staphylococcus aureus, Bacillus spp., Listeria monocytogenes and Corynebacterium jeikeium. Erythromycin resistant organisms were also resistant to dirithromycin.

In vitro activity of PD127,391, a new quinolone against bacterial isolates from cancer patients

The in vitro activity of PD127,391, a new 4-quinolone, was compared to that of ciprofloxacin against common clinical bacterial isolates from patients with cancer. PD127,391 was found to have a broad antimicrobial spectrum with excellent activity against gram-positive isolates (including multidrug-resistant organism such as Corynebacterium jeikeium, Enterococcus faecalis, Enterococcus faecium, methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp.). It was also extremely active against gram-negative bacilli including Pseudomonas aeruginosa. Against organisms such as Achromobacter xylosoxidans, Acinetobacter spp. and Xanthomonas maltophilia, which are frequently resistant to a variety of antimicrobial agents, PD127,391 exhibited good activity, inhibiting all such isolates at a concentration of 0.5 micrograms/ml. Overall, PD127,391 was far more potent than ciprofloxacin against gram-positive isolates and slightly more active against gram-negative isolates. No bacterium that we examined needed more than 2 micrograms/ml of PD127,391 for inhibition.

A comparison of the effects of tetraplatin and cisplatin on renal function and gentamicin pharmacology in rats

Tetraplatin (tetrachloro[d,l-trans]1,2-diaminocyclohexane platinum IV (TTP)) is a new platinum analogue active against L1210 murine leukemia that is resistant to cisplatin (diamminedichloroplatinum II (DDP)). Since nephrotoxicity is a significant problem with DDP therapy, we compared the effects of equitherapeutic doses of TTP and DDP on renal structure and function in rats. We also studied the effects of the 2 platinum compounds on the distribution and excretion of gentamicin (GENT), an antibiotic that is excreted solely by the kidneys. Rats treated intravenously with 2.85 mg/kg of DDP on days 1, 5 and 9 had significantly different plasma urea nitrogen (BUN) levels and creatinine clearance rates on day 16 than those given the same doses of TTP. The renal function of TTP-treated rats did not differ from that of controls or rats given only GENT. Twenty-four hours after a single GENT dose (given on day 15), DDP-treated rats had higher GENT concentrations in the plasma, liver and spleen than rats given GENT alone. TTP-treated rats had higher GENT levels only in the spleen. DDP-treated rats retained a higher percentage of the injected platinum in the renal cortex than those treated with TTP. Light microscopic examination of renal tissue showed necrotic cells and dilated tubules in the proximal tubules of DDP-treated rats while the kidneys of TTP-treated rats were largely indistinguishable from those of controls. Thus, our results indicate that the distribution of platinum in the kidneys differs between rats treated with TTP and those treated with DDP. This may partly explain the considerably lower nephrotoxicity of TTP.