Differential effect of cyanohydroxybutene on glutathione synthesis in liver and pancreas of male rats

1-Cyano-2-hydroxy-3-butene (CHB), an aliphatic nitrile found in cruciferous vegetables, causes a two- and sevenfold elevation in reduced glutathione (GSH) in rat liver and pancreas, respectively, after oral administration of 200 mg/kg. While this dose is also associated with pancreatotoxicity, a single 100 mg/kg dose or multiple lesser doses show the same effect, although somewhat reduced in magnitude, with no concomitant toxicity. In an attempt to identify the mechanism of this increase, we investigated the effect of CHB on GSH synthesis by examining the effect of buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, on CHB-induced GSH elevation. Male Fischer 344 rats received 3 mmol BSO/kg ip 24 and 34 hr following CHB or corn oil. The CHB-mediated elevation in hepatic and pancreatic GSH was eradicated by BSO, suggesting that increased synthesis was responsible. The rate-limiting step in synthesis is gamma-glutamyl cysteine synthetase (GCS); the limiting substrate is cysteine. Therefore, CHB effects on GCS activity and hepatic and pancreatic cysteine equivalents were investigated. When rats were treated by gavage with CHB (100 mg/kg), hepatic GCS mRNA concentrations were increased 24 hr after treatment and hepatic cysteine equivalents were significantly elevated 4 hr following CHB. No significant elevation in hepatic GCS activity was observed, however, even 24 hr following CHB. Pancreatic cysteine equivalents were elevated at both 4 and 8 hr after CHB treatment. However, there was no detectable GCS mRNA or activity in pancreas, in either control or treated animals. Furthermore, CHB had no direct effect on the activity of GCS purified from kidney, regardless of whether GSH was present or absent. These results suggest that the mechanism of CHB-mediated induction of GSH may involve early increases in GSH precursors as well as a later increase in GCS mRNA. The mechanism of GSH elevation identified in these studies may hold therapeutic or prophylactic implications.

The use of biphasic linear ramped pulsed field gel electrophoresis to quantify DNA damage based on fragment size distribution

PURPOSE

The development of biphasic linear pulse ramping gel electrophoresis has permitted resolution of DNA fragments from 200 Kbp to 6 Mbp in a single gel. We used this technique to measure radiation-induced DNA damage based on fragment size.

METHODS AND MATERIALS

Human colon cancer cells (HT29 and LS174T) and Chinese hamster ovary cells were embedded in agarose, deproteinized, irradiated with 5-80 Gy, and assessed for DNA double strand breakage using pulsed field gel electrophoresis. The frequency of DNA double strand breakage determined using a previously published method was compared to the breakage frequency calculated using the fragment size distribution.

RESULTS

Both methods produced similar estimates for breakage frequency of approximately 5 x 10(-9) breaks Gy-1 bp-1.

CONCLUSIONS

These findings suggest that biphasic linear pulse ramping gel electrophoresis can yield a quantitative estimate of DNA fragment distribution resulting from irradiation. The ability to quantify the distribution of DNA fragment sizes produced by irradiation should yield important information concerning the mechanisms of both DNA double strand break induction and repair.

Fine-structure analysis of the P7 plasmid partition site

The par region of bacteriophage P7 is responsible for active partition of the P7 plasmid prophage into daughter cells. The cis-acting partition site was defined precisely as a 75-bp sequence that was necessary and sufficient to promote correct segregation of an unstable vector plasmid when the two P7 partition proteins, ParA and ParB, were supplied in trans. Roughly the same region was necessary to exert partition-mediated incompatibility. The minimal site contains an integration host factor (IHF) protein binding site bracketed by regions containing heptamer repeat sequences that individually bind ParB. An additional sequence forms the left boundary of the site. Site-directed mutations in the latter sequence, as well as the IHF motif and the rightmost ParB box, blocked site function. Although the P7 site shares 55% sequence identity with its counterpart in bacteriophage P1, functional interactions between the partition sites and the Par proteins of the two plasmids were entirely species specific in vivo. The P1 sequence has similar IHF and ParB binding motifs, but the left boundary sequence differs radically and may define a point of species-specific contact with the Par proteins. No evidence was found for the existence of a functional P7 analog of the P1 parS core, a small subregion of the P1 site that, in isolation, acts as an enfeebled partition site with modified incompatibility properties.

Fungal catabolic gene regulation: molecular genetic analysis of the amdS gene of Aspergillus nidulans

Aspergillus nidulans is an excellent experimental organism for the study of gene regulation. Genetic and molecular analyses of trans-acting and cis-acting mutations have revealed a complex pattern of regulation involving multiple independent controls. Expression of the amdS gene is regulated by the facB and amdA genes which encode positively acting regulatory proteins mediating a major and a minor form of acetate induction respectively. The product of the amdR gene mediates omega amino acid induction of amdS. The binding sites for each of these proteins have been localised through amdS cis-acting mutations which specifically affect the interaction with the regulatory protein. The global controls of nitrogen metabolite repression and carbon catabolite repression regulate the expression of many catabolic genes, including amdS. Nitrogen control is exerted through the positively acting areA gene product and carbon control is dependent on the creA gene product. Each of the characterized regulatory genes encodes a DNA-binding protein which recognises particular sequences in the amdS promoter to activate or repress gene expression. In addition, there is evidence for other genetically uncharacterized proteins, including a CCAAT-binding complex, which interact with the 5' region of the amdS gene.

Reflective fiber ring resonator with polarization-independent operation

A polarization-insensitive fiber-optic ring-resonator configuration based on a reflective mode of operation with a Faraday rotator mirror for birefringence compensation is reported. An output resonant-dip transfer function that is independent of the input polarization to the system is obtained, which is shown to produce a stable scale factor of the system.

Phosphonate-modified Gd-DTPA complexes. III: The detection of myocardial infarction by MRI

The potential of a phosphonate-modified-Gd-DTPA for MR image enhancement of myocardial infarction has been demonstrated in imaging experiments on rats. The agent, 1-hydroxy-3-aminopropane-1,1-diphosphonate-modified-Gd-DTPA (Gd-DTPA-HPDP) accumulates in two models of myocardial infarction, (i.e., drug-induced diffusely infarcted whole hearts and in focal acute myocardial infarction from a left coronary artery ligation). The time course of the accumulation of the agent in the focal model of infarction and subsequent washout has also been followed in vitro. Results of this kinetics demonstrate that the agent first perfuses all normal fluid spaces and then slowly diffuses into the occluded zone where it is retained for a prolonged period, in sufficient quantities to be useful as an MRI contrast agent. Wash-out of the agent from normal myocardium is fast and complete with MR signal returning to background in minutes. The specificity of Gd-DTPA-HPDP for soft-tissue calcification and its retention within the infarcts permitted imaging at 1 to 2 h postinjection, (after unbound material has cleared the normal tissues). Infarcted tissue appeared as regions of increased signal intensity in T1-weighted images (> 200% enhancement), and correlated with histopathology. Unmodified Gd-DTPA was not retained under identical conditions. Gd-DTPA-HPDP permits a more accurate infarct delineation than is possible with the unmodified agent.

In vitro metabolism of cyanohydroxybutene: formation of a glutathione-S-transferase catalyzed product

The pancreatotoxin cyanohydroxybutene (CHB) causes a significant and prolonged elevation in glutathione (GSH) in liver and pancreas (Wallig and Jeffery, 1990). Here we report that urinary thiols also increase. This suggests that CHB may react with GSH, either directly or following phase I oxidation, to form an adduct, which is further metabolized to the corresponding mercapturic acid for urinary excretion. Metabolism of CHB by hepatic mixed function oxidase and cytosolic alcohol dehydrogenase enzymes was evaluated by monitoring microsomal NADPH consumption and alcohol dehydrogenase-dependent NADH generation, respectively. There was no apparent increase in the rate of microsomal NADPH consumption or alcohol dehydrogenase-dependent NADH generation in the presence of CHB. To evaluate in vitro formation of a glutathione-S-transferase (GST) catalyzed adduct, [3H-glycyl]-GSH and [14C-cyano]-CHB were incubated at 37 degrees C for 1 h, with or without GST. Dinitrophenol derivatization and high performance liquid chromatographic (HPLC) analysis (Farris & Reed, 1987) revealed no double-labeled peaks, suggesting that no stable conjugate was formed. However a tritiated product, not present in control samples, and with an identical retention time to cysteinyl-glycine (cys-gly) was formed. In addition, the product has a fast atom bombardment mass-spectrum consistent with cys-gly. These results suggest that while CHB may not undergo phase I oxidation, in the presence of CHB, GSH may break down to form cys-gly. A mechanism for CHB-dependent breakdown of GSH to cys-gly is proposed, and the pharmacological implications of this finding are discussed.

Effects of a novel NMDA antagonist on experimental stroke rapidly and quantitatively assessed by diffusion-weighted MRI

We employed diffusion-weighted MRI (DWI) to identify regions of focal brain ischemia during the first 3 hours after permanent occlusion of the middle cerebral artery in rats. Using DWI as early as 30 minutes after the onset of ischemia, it was possible to identify the areas of brain destined to progress to infarction over the next 24 hours in untreated animals, as demonstrated by postmortem evaluation. DWI studies revealed the cerebroprotective effects of a noncompetitive N-methyl-D-aspartate receptor antagonist, CNS 1102, administered 15 minutes postocclusion, both on the cortical and caudoputaminal regions during the initial 3 hours of ischemia. Although the treatment effect lessened over the next 21 hours in a few animals with lower plasma drug levels at 3 hours, postmortem studies demonstrated a 66% reduction in the total volume of infarcted tissue with the treatment and confirmed the DWI results. T2-weighted MRI obtained at similar times revealed little or no abnormality. These results suggest that DWI provides a sensitive in vivo measure of focal cerebral ischemic injury and can assess the beneficial effects of cytoprotective therapy. DWI may be useful in the early evaluation of human stroke patients and in monitoring the effects of cerebroprotective therapies in the clinical setting.

In vitro dissolution of cholesterol gallstones

RATIONALE AND OBJECTIVES

Methyl tert-butyl ether (MTBE) is the solvent most commonly used for in vivo dissolution of cholesterol gallstones. Its limitations, however, include high volatility and flammability along with potential toxicologic concerns. Therapy may take several hours. This study was initiated to identify alternate solvents which may be superior to MTBE in one or more of these areas.

METHODS

MTBE was compared with several other solvents for cholesterol-dissolving capacity. Groups of human cholesterol gallstones were placed in test tubes, and, without agitation, subjected to mixtures of MTBE:ethanol or another solvent:ethanol.

RESULTS

Six other solvents were found to have higher capacities. In several cases, other solvent mixtures dissolved gallstones up to twice as fast as the MTBE:ethanol mixture. These faster solvents were cyclic ethers (tetrahydrofuran [THF], methyl tetrahydrofuran [MTHF], tetrahydropyran [THP], methyl tetrahydropyran [MTHP], and possibly dimethyl tetrahydrofuran [DMTHF]) and limonene. Some of these solvents also have lower volatility and higher flash points than MTBE, resulting in safer storage and handling. THF and pyridine, however, were found to precipitate bile components when mixed with bile.

CONCLUSION

The authors describe solvents that may be superior to MTBE for rapid dissolution of gallstones in vivo.

Correlates of knee pain among US adults with and without radiographic knee osteoarthritis

We examined the associations of sociodemographic variables, health behaviors, health status and psychological well being with radiographic knee osteoarthritis (OA) and self-reported knee pain for 4056 US adults aged 45-74 years. Among persons with or without knee OA known correlates of radiographic knee OA (age, sex, race, obesity) were generally not associated with knee pain. Radiographic severity, psychological well being and health status were associated with knee pain, both among persons with and without radiographic knee OA, suggesting that nonradiographic correlates of self-reported knee pain are independent of whether a person has radiographic knee OA.

Structural and functional analysis of the amdR regulatory gene of Aspergillus oryzae

We have isolated the Aspergillus oryzae homologue of the amdR regulatory gene of Aspergillus nidulans by cross hybridization. Sequence analysis and functional studies have shown that the amdR genes are highly conserved and functionally interchangeable between the two species. The homology between the two genes extends throughout most of the coding sequences, including sequences encoding the DNA-binding domain and putative activation domains. Two regions of nonconserved sequence were also identified. Studies using various amdS::lacZ fusion constructs indicate that the A. oryzae gene product binds similar sequences and responds to inducer in a similar manner to the A. nidulans protein. Inactivation of the A. oryzae gene results in the inability to grow on gamma-amino-butyric acid (GABA) as a carbon and/or nitrogen source indicating that GABA utilization is amdR-dependent in A. oryzae as it is in A. nidulans.

Effect of recombinant alpha interferons on fertility and interestrous interval in sheep

In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 to 14 of one of the following treatments: 1) ovine conceptus secretory proteins (oCSP) containing 25 microg of ovine trophoblast protein-1 (oTP-1) as determined by RIA; 2) 25 or 50 microg recombinant human interferon alpha1 (rhlFN); or 3) 1500 microg of serum proteins (oSP) from a Day-16 pregnant ewe (estrus = Day 0) per uterine horn. Ewes receiving oCSP had longer interestrous intervals (27 +/- 2 days; P<0.05) than ewes receiving oSP (17 +/- 2 days). Ewes receiving either dose of rhlFN had an interestrous interval of 16 +/- 2 days which did not differ (P>0.10) from that of oSP-treated ewes. In Experiment 2, 59 normally cycling ewes, mated on Day 0, received twice-daily intramuscular injections of either 2 mg recombinant bovine interferon alpha1 (rblFN) or placebo on Days 12 to 15 post estrus. On Day 16, pregnancy was confirmed by flushing a morphologically normal conceptus from the uterus. Pregnancy rates for rblFN-treated (80%) and placebo-treated (62%) ewes were not different (P>0.10). Uterine flushings and conceptus-conditioned medium were assayed for oTP-1. Total oTP-1 in conceptus-conditioned culture medium was higher (P<0.02) when conceptuses were from placebo-treated (104 +/- 14 microg/conceptus) than from rblFN-treated (56 +/- 12 microg/conceptus) ewes; while total oTP-1 in uterine flushings was similar (P>0.10) for placebo-treated (132 +/- 15 microg/conceptus) and rblFN-treated (147 +/- 17 microg/conceptus) ewes. The interval from mating to subsequent estrus following conceptus removal was 31 +/- 1 and 28 +/- 1 days for pregnant ewes treated with rblFN and placebo, respectively. Interestrous intervals for nonpregnant ewes were longer (P<0.02) for rblFN-treated (27 +/- 3 days) than for placebo-treated (18 +/- 2 days) ewes.

Identification of functional regions of the positively acting regulatory gene amdR from Aspergillus nidulans

The amdR (intA) regulatory gene of Aspergillus nidulans encodes a 765-amino-acid polypeptide which determines the omega-amino acid induction of at least five structural genes. The AmdR polypeptide contains a potential Zn(II)2Cys6 DNA-binding motif which has been shown to be present in the N-terminal region of a large number of fungal activator proteins. In vitro mutagenesis of the fourth cysteine of this motif abolishes AmdR function as shown by loss of complementation of an amdR- mutation and by the AmdR- phenotype of a mutant gene replacement strain. Studies using constructs in which the proposed AmdR DNA-binding motif is replaced with that from another activator, FacB, shows that induction is independent of DNA-binding specificity and that sequences in the C-terminal region of AmdR are activation domains. Sequencing of several amdR mutant alleles which affect activation and/or induction, together with studies of deletion constructs indicate that changes in the conformation of the protein determines its activity and that this is modulated by inducers.

Reversible focal ischemic injury demonstrated by diffusion-weighted magnetic resonance imaging in rats

BACKGROUND AND PURPOSE

Diffusion-weighted magnetic resonance imaging (DWI) can quantitatively display focal brain abnormalities within minutes after the onset of ischemia. We performed the present study to determine the effects of 1 and 2 hours of temporary ischemia on DWI.

METHODS

We examined DWI and T2-weighted magnetic resonance images (T2WI) during and after 1 and 2 hours of temporary middle cerebral artery occlusion in rats (n = 10 for each group). In a subgroup of four animals from each group, we employed perfusion magnetic resonance imaging to monitor cerebral perfusion. Neurological outcome and infarct size after survival for 24 hours were compared between the groups and correlated with DWI and T2WI studies.

RESULTS

Perfusion studies qualitatively documented hypoperfusion and reperfusion during and after temporary occlusion. Lesion size on DWI during reperfusion was significantly less than that during ischemia for 1 (55% decline, p less than 0.02) but not 2 hours of occlusion. The DWI signal intensity ratio (intensity compared with that in the contralateral homologous area) just before withdrawal of the occluder was significantly less in regions where the hyperintensity disappeared after withdrawal than in regions with persistent hyperintensity (p less than 0.002). The T2WI studies revealed few or no abnormalities, except after 2 hours of occlusion. The neurological outcome was significantly better in the 1-hour than in the 2-hour group (p less than 0.05). Postmortem infarct volume was significantly smaller in the 1-hour group than in the 2-hour group (p less than 0.05). The postwithdrawal DWI accurately predicted infarct size (R = 0.96, p less than 0.0001).

CONCLUSIONS

The present study indicates that DWI can rapidly display not only irreversible but also reversible ischemic brain damage and enhances the importance of DWI as a diagnostic modality for stroke.

Charge-coupled device detector: performance considerations and potential for small-field mammographic imaging applications

The physical characteristics of a charge-coupled device (CCD) image detector were evaluated, as well as its potential as a digital imaging device for small field mammographic applications such as preoperative needle localization. The detection system is based on a 2048 x 2048 pixel CCD operated in 1024 x 1024 mode. The CCD was optically coupled to an intensifying screen via a lens, without intermediate intensification. The thermal noise was suppressed to 0.15 electrons pixel-1s-1 by cooling the CCD with liquid nitrogen. The dominant source of noise was attributed to the on-chip amplifier during the readout process that was performed at 50,000 pixels s-1. The measured readout noise level was 15 electrons per pixel. The low-noise characteristics of this CCD prototype detector produced encouraging results under conditions simulating mammography, with a signal level close to one electron per pixel for each detected x ray. The mean glandular dose to the breast, based on the entrance exposure measured from a standard mammographic phantom would be 1.52 mGy (152 mrad). The ultimate spatial resolution of the system was approximately 8 cycles/mm but it was limited to about 5 cycles/mm when operated in the 1024 x 1024 imaging mode. Other physical characteristics of the system such as optical coupling efficiency, exposure response, and signal-to-noise ratio were evaluated. The results of this study suggest that the use of a scientific-grade CCD allows for very good low-contrast discrimination and moderate spatial resolution under conditions simulating mammography, but the current prototype is limited to a 9 x 9-cm2 field of view.(ABSTRACT TRUNCATED AT 250 WORDS)

The potential superiority of bromodeoxyuridine to iododeoxyuridine as a radiation sensitizer in the treatment of colorectal cancer

Although the thymidine analogues 5-bromo-2'-deoxyuridine (BrdUrd) and 5-iodo-2'-deoxyuridine (IdUrd) have been used successfully as radiation sensitizers in clinical trials, it is not clear which of these agents is the more promising to pursue. To begin to assess this question with regard to colorectal cancer metastatic to the liver, a study was carried out using HT29 human colon cancer cells in culture and implanted in nude mice as xenografts. Cells and animals were treated with BrdUrd +/- the thymidylate synthase inhibitor 5-fluoro-2'-deoxyuridine (FdUrd), and the results compared to our previous studies with IdUrd +/- FdUrd (T. S. Lawrence, M. A. Davis, P. E. McKeever, J. Maybaum, P. L. Stetson, D. P. Normolle, and W. D. Ensminger. Cancer Res., 51: 3900-3905, 1991). Using cultured cells, it was found that FdUrd (at concentrations of greater than 10 nM) increased: (a) the incorporation of BrdUrd into the DNA of cultured tumor cells; (b) BrdUrd-mediated radiosensitization; (c) BrdUrd-mediated increase in radiation-induced DNA damage; and (d) BrdUrd-mediated decrease in the repair of radiation-induced damage. The incorporation of BrdUrd was greater than or equal to the incorporation of IdUrd previously determined under the same exposure conditions. Studies using nude mice bearing HT29 xenografts showed that FdUrd increased BrdUrd incorporation more into tumors than into the normal liver. Most tumor cells incorporated BrdUrd (labeling index after a 4-day infusion = 87 +/- 2%; SE); in the liver, labeling was confined chiefly to nonparenchymal cells. In both the presence and absence of FdUrd, the incorporation of BrdUrd into tumors was significantly and consistently greater than the incorporation of IdUrd measured under the same conditions of drug administration (by a factor of 1.2-3.6). Furthermore, the administration of BrdUrd +/- FdUrd tended to produce less weight loss and hematological toxicity than IdUrd +/- FdUrd. These findings suggest that BrdUrd may be superior to IdUrd as a radiation sensitizer in the treatment of colorectal cancer metastatic to the liver.

Biochemical activities of the parA partition protein of the P1 plasmid

The unit-copy P1 plasmid depends for stability on a plasmid-encoded partition region called par, consisting of the parA and parB genes and the parS site. ParA is absolutely required for partition, but its partition-critical role is not known. Purified ParA protein is shown to possess an ATPase activity in vitro which is specifically stimulated by purified ParB protein and by DNA. ParA is responsible for regulation of expression of parA and parB, and purified ParA has an ATP-dependent, site-specific DNA binding activity which recognizes a sequence that overlaps the parA promoter. The role of the ATP-dependence of the binding activity, as well as other possible functions of the ATPase activity in partition, is discussed.

Effects of ovine conceptus secretory proteins and progesterone on oxytocin-stimulated endometrial production of prostaglandin and turnover of inositol phosphate in ovariectomized ewes

This study examined the effects of progesterone and intrauterine injection of ovine conceptus secretory proteins (oCSP) on endometrial responsiveness to oxytocin. Twelve ewes were ovariectomized on day 4 of the cycle (oestrus = day 0) and assigned in a 2 x 2 factorial arrangement, to receive either 1.5 mg ovine serum proteins (SP) or oCSP containing 25 micrograms ovine trophoblast protein 1 (oTP-1) (by radioimmunoassay) in 1.5 mg total protein into each uterine horn, via catheters, twice a day on days 11, 12, 13 and 14. Ewes received 200 mg progesterone per day (i.m.) from day 4 to day 10 or 15. Oxytocin-induced prostaglandin F2 alpha was measured as 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) on days 11, 12, 13 and 14 in plasma from three integrated, 10 min (10 ml) blood samples (0-10, 10-20, 20-30 min) obtained after intravenous injection of 20 iu oxytocin, and in a pre-oxytocin (-10 to 0 min) sample collected via an indwelling jugular catheter. The pre-oxytocin samples were also assayed for progesterone. Oxytocin-induced turnover of inositol phosphate was determined in endometrium on day 15 after hysterectomy. In ewes receiving progesterone to day 10, plasma progesterone decreased from about 12 to 2 ng ml-1 (SEM +/- 2.6) during the treatment period (days 11-14), but remained high (12-20 +/- 2.6 ng ml-1) in ewes that received progesterone to day 15. Intrauterine injection of oCSP resulted in high basal concentrations of PGFM on days 12 and 13 compared with SP-treated ewes (P less than 0.01). Treatments with progesterone did not affect basal PGFM concentrations. Treatment with oCSP abolished oxytocin-induced endometrial secretion of prostaglandin only if progesterone was maintained to day 15 (P less than 0.01); in ewes receiving such treatment, oCSP inhibited (P less than 0.01), but SP did not inhibit, oxytocin-induced endometrial turnover of inositol phosphate (P less than 0.06), which was greater in ewes treated with progesterone to day 10 than in those treated to day 15 (P less than 0.05). Ewes that responded to oxytocin with increased PGFM exhibited increased oxytocin-stimulated turnover of inositol phosphate on day 15. These results indicate that the antiluteolytic action oTP-1 exerts on the endometrium requires progesterone and that this mechanism involves inhibition of oxytocin-stimulated turnover of inositol phosphate.

Prevention of urinary tract infection and bacteremia following transurethral surgery: oral lomefloxacin compared to parenteral cefotaxime

A multicenter, randomized, open label study compared the safety and efficacy of a single dose of oral lomefloxacin, a broad-spectrum antimicrobial agent of the quinolone class, to a single parenteral dose of cefotaxime, a third generation cephalosporin, for prophylaxis in transurethral surgery. Of the 230 patients initially recruited 182 were considered evaluable: 92 in the lomefloxacin group and 90 in the cefotaxime group. Both study groups were well balanced with respect to demographics and transurethral procedures. Efficacy and safety were evaluated with urine cultures, clinical laboratory evaluations and monitoring of adverse events. The success rate among the lomefloxacin patients was 98% versus 94% in the cefotaxime patients. The difference was not statistically significant. Adverse events, regardless of attributability, were reported by 16% of the lomefloxacin patients and 17% of the cefotaxime patients, respectively. Our results indicate efficacy and safety profiles of lomefloxacin equivalent to cefotaxime. Lomefloxacin has the economic advantage of an oral route of administration compared to the parenteral route of cefotaxime for prophylaxis in transurethral genitourinary procedures.

Diffusion-weighted magnetic resonance imaging: rapid and quantitative detection of focal brain ischemia

We examined serial changes of diffusion- (DWI) and T2-weighted (T2WI) magnetic resonance images 30 minutes to 3 hours after intraluminal suture occlusion of the middle cerebral artery (MCA) in eight rats and after sham occlusion in four. We correlated the abnormal areas on DWI and T2WI with postmortem areas of infarction determined by 2,3,5-triphenyltetrazolium chloride (TTC), 24 hours after the operation. The 30-minute DWI in each MCA-occluded rat demonstrated increased signal intensity in the ipsilateral MCA territory, while T2WI showed no changes. At 3 hours, the ipsilateral DWI signal intensity increased further and the area of abnormality slightly increased. In some animals, the 3-hour T2WI disclosed an area of hyperintensity significantly smaller than that seen on the 30-minute DWI. TTC staining demonstrated an extensive MCA infarction in all rats with permanent MCA occlusion, confirmed by hematoxylin and eosin staining. The percent infarcted area of coronal brain sections, as determined by TTC staining, correlated significantly with areas on similar DWI sections at both 30 minutes and 3 hours. Sham-occluded control animals did not display any changes on DWI, T2WI, or TTC staining. The present study suggests that DWI is a very sensitive modality for detecting early ischemic brain injury, being highly correlated with post-mortem area of infarction, and may be useful to assess pharmacologic intervention.

Living arrangements and survival among middle-aged and older adults in the NHANES I epidemiologic follow-up study

BACKGROUND

There is concern about but little information on how living alone affects the health and survival of older adults.

METHODS

We examined the association between living arrangements (living alone, with a spouse, or with someone other than a spouse) and survival among 7651 adults, aged 45 to 74 years in the National Health and Nutrition Examination Survey (NHANES I) (1971-1975) and traced at the NHANES I Follow-up Study (1982-1984), to see whether certain sociodemographic factors (race, education, income, and employment), health behaviors (alcohol, smoking, physical activity, and obesity), or chronic medical conditions were influential in the association.

RESULTS

We found a stronger association of living arrangements with survival for men than for women, and for middle-aged men than for older men. For men, those living alone and those living with someone other than a spouse were equally disadvantaged in terms of survival. Income, race, employment, and physical activity influenced the association of living arrangements and survival, but their impact varied by age, gender, and living arrangement.

CONCLUSION

Living arrangements had a weak impact on survival among men, but had no effect among women.

Is calcium oxalate an adequate explanation for nonvisualization of breast specimen calcifications?

This study was initiated to determine whether the apparent calcium loss during histologic breast specimen processing could be explained by the presence of birefringent, transparent calcium oxalate crystals (type I). In previous investigations, the authors had noted a possible loss of 26.2% of calcium during the processing and sectioning of breast specimens. Two hundred thirteen histologic slides prepared from blocks demonstrating calcium radiographically but not histologically were reviewed with polarized light. An additional 506 slides from 19 malignancies appearing as microcalcifications were also reviewed with polarized light. Only one slide from each group (0.2% and 0.5% from the malignant and benign groups, respectively) demonstrated birefringent calcium oxalate (type I). Thus, the presence of calcium oxalate does not sufficiently explain the non-visualization of calcium, which is due instead to processing of breast specimens.

Modulation of iododeoxyuridine-mediated radiosensitization by 5-fluorouracil in human colon cancer cells

The incorporation of 5-iodo-2'-deoxyuridine (IdUrd), a thymidine analog radiosensitizer, can be increased by the use of modulators such as 5-fluorouracil (FUra). FUra is a particularly attractive potential modulator to use against colorectal cancer, as it is the most active single agent in the treatment of this disease. To begin to define the conditions for the optimal combination of IdUrd and FUra in the treatment of patients with colorectal cancer, a study was conducted of the effect of FUra on IdUrd-mediated radiosensitization in cultured HT29 human colon cancer cells. It was found that when cells were exposed to concentrations of IdUrd typical of those obtained through intravenous exposure (1-3 microM), FUra (1 microM) increased radiosensitization beyond that which would be predicted for the same extent of incorporation produced by incubation with IdUrd alone. This increase appeared to result from a combination of at least two effects: FUra-mediated cell cycle redistribution and increased IdUrd incorporation. When a higher concentration of IdUrd (10 microM) was used with FUra (1 microM), cell cycle distribution returned to nearly normal, and radiosensitization was equal to that predicted by the extent of incorporation of IdUrd. These data demonstrate that the combination of FUra and IdUrd can produce radiosensitization both through increased IdUrd incorporation and cell cycle redistribution. Furthermore, they suggest that, in the presence of a modulator, it may not be necessary to achieve high levels of IdUrd incorporation to produce significant tumor radiosensitization.

Age and sex differences in variation of nutrient intakes among U.S. adults

Studies assessing associations of diet with health frequently use multi-day dietary records to estimate usual dietary intakes. We examined variation in intakes of 13 nutrients for 13,388 U.S. adults using 3 days of dietary data from the 1977-1978 Nationwide Food Consumption Survey. Ratios of within-person variability to between-person variability in intakes were large and would result in attenuated linear regression estimates of diet-health associations. For many nutrients, the magnitude of the attenuation decreased with age for both sexes but particularly for men, implying that fewer days of dietary intake per person would correctly assess diet-health associations among older adults than have been suggested for younger adults.

Breast specimen microcalcifications: radiographic validation and pathologic-radiologic correlation

A prospective analysis of specimens from location and biopsy of mammographically suspect microcalcifications in 108 patients was carried out to determine if microcalcifications were lost during histopathologic processing and the clinical relevance of such loss. Nine hundred sixty-eight paraffin blocks were prepared from 425 gross tissue slices containing calcifications identified at radiography of the specimens. Calcium was apparently lost both during preparation of the blocks (13.6%) and after slide preparation (12.6%), for a total possible loss of 26.2%. All specimens demonstrated calcification histologically. One pathology report was amended because of information obtained after recuts, but all cancers were detected on original slides whether or not calcifications were identified initially. The results indicate that, by following the suggestions offered to ensure adequate histopathologic sampling of calcification seen at mammography, most if not all of the calcification present can be detected on the original slide.

Fluorodeoxyuridine-mediated modulation of iododeoxyuridine incorporation and radiosensitization in human colon cancer cells in vitro and in vivo

A study was conducted to assess the potential of 5-fluoro-2'-deoxyuridine (FdUrd) to increase the incorporation and radiosensitizing properties of 5-iodo-2'-deoxyuridine (IdUrd) using HT29 human colon cancer cells both in vitro and in nude mice bearing these tumors as xenografts. The purpose of this study was to assess (a) whether FdUrd could increase IdUrd efficacy using clinically achievable concentrations of drugs; (b) the relationships among radiosensitization, DNA damage and repair, and analogue incorporation; and (c) whether FdUrd improved the selectivity of IdUrd incorporation into tumor cells compared to normal tissues. It was found that FdUrd, at clinically achievable concentrations (1-100 nM), significantly increased IdUrd incorporation under all conditions but particularly when the IdUrd concentration was less than or equal to 10 microM. FdUrd increased IdUrd-mediated radiosensitization in proportion to the increase in IdUrd incorporation. FdUrd potentiated the ability of IdUrd to increase radiation-induced DNA double-strand breaks and to slow their repair. When IdUrd alone (100 and 200 mg/kg/day) was infused into nude mice bearing tumors, the extent of thymidine replaced in the tumor was 1.6 +/- 0.4 (mean +/- SE) and 2.5 +/- 0.4%, respectively. The combination of FdUrd (0.1 mg/kg/day) and IdUrd (100 mg/kg/day) increased the incorporation in the tumor to 5.3 +/- 0.9% with less toxicity than resulted from the use of 200 mg/kg/day of IdUrd alone. These data show that FdUrd is an effective biomodulator, because, for the same extent of normal tissue incorporation, the combination of IdUrd and FdUrd produces significantly greater incorporation into the tumor compared to the use of IdUrd alone. Furthermore, they suggest that the regional application of FdUrd with IdUrd, either through the use of regional infusions or in combination with focused irradiation, could potentially improve the outcome of treatment of localized gastrointestinal cancer.

Insulin-like growth factors in sheep uterine fluids: concentrations and relationship to ovine trophoblast protein-1 production during early pregnancy

Uterine luminal fluids (ULFs) from Days 10, 12, 14, and 16 cyclic (C) and pregnant (Px) ewes were analyzed for presence of insulin-like growth factors (IGF-I, IGF-II) and other mitogenic factor(s). IGF content and non-IGF mitogenic activity were measured by IGF RIAs after removal of IGF binding proteins and by stimulatory effects on DNA synthesis of density arrested AKR-2B cells, respectively. ULF IGF-I content was not different between days, but differences in IGF-I between C and Px groups at Day 16 (C greater than Px) were found (p less than 0.05). ULF IGF-II content was not different between C and Px ewes; however, differences among days (p less than 0.01) were apparent. In both C and Px ewes, Day 14 ULF had highest IGF-II content (C: 4.60 +/- 0.98 ng/ml, Px: 5.39 +/- 1.38 ng/ml). In Day 12 and Day 14 (C and Px) ULF, IGF-II concentration was about 10-fold greater than that of IGF-I. AKR-2B mitogenic activity in ULF differed among days (p less than 0.01), but not between C and Px ewes. Highest activity was observed for Day 14 and Px ULF, whereas lowest activity was for Day 10 C and Day 16 Px ULF. Sephadex G-200 gel-filtration chromatography of ULF from Day 14 Px ewes demonstrated mitogenic activity in the column void volume fractions and in the 30-kDa size range of eluted proteins. Day 13 conceptuses were cultured in serum-free medium to define the effect of exogenous IGFs on ovine trophoblast protein-1 (oTP-1) secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Gadolinium-labeled liposomes containing various amphiphilic Gd-DTPA derivatives: targeted MRI contrast enhancement agents for the liver

Unique paramagnetic liposomal contrast agents were synthesized and utilized for selective augmentation of T1 MR imaging of the livers of normal Balb/c mice. A series of amphipathic gadolinium complexes, which mimic phospholipids, was incorporated into the lamella of small unilamellar liposomes such that they become an integral part of its surface. The amphipathic complexing agents consisted of DTPA reagents in which two stearyl chains are attached via amide, ester, and thioester linkages. The in vitro stability and the in vivo lifetimes of the new amphipathic agents were dependent on the method used to attach the long-chain alkyl groups.

Fine-structure analysis of the P1 plasmid partition site

P1 plasmid partition requires two plasmid-encoded Par proteins and a cis-acting site. The site, parS, lies in a region consisting of a 13-bp palindrome and an adjacent AT-rich sequence. A series of point mutations were analyzed for their effects on partition site activity. The results indicated that only the left arm of the palindrome and some adjacent bases were needed. The limits of the functional site were further refined to a maximum of 22 bp, which includes binding sites for the P1 ParB protein. Mutations in the 22-bp site cause concomitant defects in partition and the ability to exert partition-mediated incompatibility. Like the region immediately to the left of the 22-bp region, the right arm of the palindrome is not essential for partition but does contain information that affects the specificity of incompatibility.

Knee osteoarthritis and physical functioning: evidence from the NHANES I Epidemiologic Followup Study

Although osteoarthritis (OA) is common among adults, little is known about its long-term impact on physical function. Therefore, in a cohort of 2,884 adults aged 45 years or older, [National Health and Nutrition Examination Survey I (NHANES I 1971-1975)] we examined the association of baseline radiographic knee OA and difficulty in physical functioning 10 years later (NHANES I Followup Study 1982-1984). In sex specific analyses, after controlling for age, race and length of followup, persons with radiographic knee OA were more likely than persons without knee OA to report difficulty with physical functioning, particularly for activities involving mobility, transfer and instrumental activities of daily living. However, the association of knee OA with physical functioning was influenced by the radiographic grade of OA and knee pain at NHANES I, suggesting that disease severity and pain are important in anticipating difficulties with physical functioning in persons with knee OA.

Induction of megabase DNA fragments by 5-fluorodeoxyuridine in human colorectal tumor (HT29) cells

Current evidence suggests that DNA fragmentation plays an integral role in mediating cytotoxicity that results from thymidine nucleotide depletion ("thymineless death"). Recently, Ayusawa et al. [Mutat. Res. 200:221-230 (1988)] reported that dTMP starvation induces cellular processes that result in the release of 50-200-kilobase (kb) DNA fragments in FM3A cells, as detected by pulsed field gel electrophoresis (PFGE). The present study was undertaken to determine whether a similar DNA fragmentation process occurs in a human cell line in response to fluoropyrimidine treatment and, if so, to quantitate this process. When human colorectal tumor (HT29) cells were treated with 100 nm 5-fluorodeoxyuridine (FdUrd), this regimen induced the formation of high molecular weight DNA fragments, which were analyzed using three different PFGE protocols. Field inversion PFGE revealed that, in contrast to the discrete size range reported for FM3A cells, FdUrd-induced fragments in HT29 cells were broadly distributed from about 50 kb to sizes beyond the resolution of the field inversion mode (i.e., greater than 600 kb). Analysis of these same samples by contour-clamped homogeneous electric field PFGE showed that the bulk of these fragments migrated in the 1-5-megabase region. In contrast, fragments from DNA that was broken randomly by gamma-radiation appeared to be primarily in a zone corresponding to approximately 5-10 megabases. Equitoxic FdUrd and radiation treatments (100 nM FdUrd for 48 hr versus 10-Gy gamma-radiation) each increased the fraction of DNA entering the gel from about 0.07-0.09 (untreated cells) to about 0.22-0.25. To a first approximation, the time course and quantity of DNA fragmentation induced by 100 nM FdUrd appeared to correlate with the loss of clonogenicity within the 48-hr period analyzed. These findings suggest that the processes responsible for DNA fragmentation in response to a thymineless state may be different in FM3A and HT29 cells, that in both cases the breaks caused do not appear to be located randomly with respect to the entire genome, and that these processes may be related to the chain of events by which temporary dTMP starvation is made into a lethal insult.

Gadolinium-labeled liposomes containing amphiphilic Gd-DTPA derivatives of varying chain length: targeted MRI contrast enhancement agents for the liver

Paramagnetic liposomal contrast agents were synthesized and utilized for selective augmentation of T1 MR imaging of the livers of normal Balb/c mice. Amphiphilic gadolinium complexes, which mimic phospholipids, were incorporated into the lamella of small unilamellar liposomes (SUV) such that they become an integral part of its surface. The amphiphilic complexing agents consisted of DTPA reagents in which a pair of alkyl chains of varying lengths are attached via amide linkages. The in vivo lifetimes of the amphiphilic agents were found to be dependent on the chain length of the alkyl groups.

Obesity and osteoarthritis of the knee: evidence from the National Health and Nutrition Examination Survey (NHANES I)

The importance of systemic/metabolic factors in the association of obesity with radiographic knee osteoarthritis (OA) was examined for 3,905 adults aged 45 to 74 from the United States National Health and Nutrition Examination Survey, 1971 to 1975 (NHANES I). Obesity was associated with both bilateral and unilateral OA, but more strongly with bilateral OA. Obesity was also associated with both symptomatic and nonsymptomatic knee OA. Controlling for age, sex, serum cholesterol, serum uric acid, diabetes, body fat distribution, bone density, and blood pressure did not significantly reduce the association between obesity and knee OA. Findings from these data are not supportive of a metabolic link between obesity and knee OA.

Living arrangements and dietary quality of older U.S. adults

The association between living arrangement and dietary quality of older U.S. adults was investigated in 4,402 adults aged 55 years or older who participated in the Nationwide Food Consumption Survey, 1977 to 1978. Dietary quality was based on percent of Recommended Dietary Allowances for 3-day intakes of nine nutrients. More men living alone consumed a poor-quality diet than did men living with a spouse, particularly those 75 years or older; for women, this effect was seen only in the 55- to 64-year-old group. In general, more women than men had poor-quality diets. A number of factors (economic, employment, health status, energy intake, body mass index, and nutrient supplement use) were examined for their importance in accounting for differences in dietary quality of older men and women living alone compared with those living with a spouse. Energy intake was the most important variable accounting for the association of living arrangement with dietary quality. Evidence indicated that older adults living alone did not make poorer food choices than those living with a spouse, but rather that they consumed fewer calories.

Body fat distribution and osteoarthritis

The association of body fat distribution with single and combined site osteoarthritis was investigated using data from the US Health Examination Survey I, 1960-1962 (HES I) and the first National Health and Nutrition Examination Survey I, 1971-1975 (NHANES I). The study included 1,636 adults aged 35-79 years from HES I with hands and feet radiographs and four anthropometric fat distribution measures--subscapular and triceps skinfolds, waist girth, and seat breadth--and 3,885 adults aged 45-74 from NHANES I with knee radiographs and subscapular and triceps skinfold measures. Sex-specific data, adjusted for age, race, and body mass index, were analyzed using polychotomous logistic regression. There was a positive association of body mass index with knee osteoarthritis and with combined hands and feet osteoarthritis. A peripheral body girth pattern was associated with combined site osteoarthritis of the hands and feet; however, there was no consistent pattern of association of body fat distribution with knee osteoarthritis nor with osteoarthritis of the hands or feet only. These findings suggest that the central body fat pattern observed in previous studies to be associated with cardiovascular and gallbladder disease, and with diabetes, is not associated with osteoarthritis of the hands, feet, or knees.

Leuprolide with and without flutamide in advanced prostate cancer

In a randomized, double-blind trial for metastatic prostate cancer (Stage D2), 603 men received leuprolide, a gonadotropin-releasing hormone analog that inhibits the release of gonadotropins, coupled with either placebo or flutamide, a nonsteroidal antiandrogen that inhibits the binding of androgens to the cell nucleus. The 303 men receiving androgen blockade with leuprolide and flutamide demonstrated a longer progression-free survival (16.9 vs. 13.9 months, P = 0.039) and an increased median length of survival (35.0 vs. 27.9 months, P = 0.035). In the subgroup of men with minimal disease and good performance status, the advantages of maximal androgen blockade were more pronounced. It is concluded that combined androgen blockade with leuprolide and flutamide was more effective than leuprolide alone for patients with metastatic cancer of the prostate. The therapeutic benefits, although greatest in patients with minimum disease, need to be evaluated in a prospective, randomized fashion in trials specifically designed for men with minimal disease and good performance status. Exploratory analyses using the black race as an explanatory variable were also performed. Black race is associated with shorter survival times and is also associated with other prognostic factors, including recent weight loss, anemia, elevated phosphatase levels, and pain. These findings suggest the need for future studies of the relationship of black race and response to prostate cancer therapy.

The effect of single versus double-strand substitution on halogenated pyrimidine-induced radiosensitization and DNA strand breakage in human tumor cells

To better understand the mechanism underlying halogenated pyrimidine-mediated cytotoxicity and radiosensitization in human tumor cells, a study was undertaken to determine the influence of unifilar (one DNA strand) versus bifilar (both DNA strands) substitution of thymidine by the halogenated bases 5-iodo-2'-deoxyuridine (IdUrd) and 5-bromo-2'-deoxyuridine (BrdUrd) in HT29 human colon cancer cells. Unifilar labeling was obtained by incubating cells with IdUrd or BrdUrd for one doubling time. Cells were incubated for at least three doublings to approximate bifilar substitution. Only IdUrd caused significant cytotoxicity, which correlated with incorporation into DNA. Both BrdUrd and IdUrd were potent radiosensitizers. Radiosensitization was linearly correlated with incorporation of both bases regardless of the number of strands in which thymidine was substituted. In contrast, the relationship between radiosensitization and DNA double-strand breakage was critically dependent in the case of IdUrd, but not for BrdUrd, on whether substitution was unifilar or bifilar. These findings suggest that incorporation is the best predictor of radiation sensitivity, and that the induction of DNA double-strand breaks alone does not account for radiosensitization mediated by halogenated pyrimidines in these human tumor cells.

The influence of Na+,K(+)-pump blockade on doxorubicin-mediated cytotoxicity and DNA strand breakage in human tumor cells

We have previously shown that blockade of the Na+,K(+)-pump by the cardiac glycoside ouabain produces doxorubicin resistance and decreases topoisomerase II-mediated DNA strand breakage in hamster cells. To determine if this were a general phenomenon, the effect of pump blockade on doxorubicin resistance was assessed in three human tumor cell lines: A549 lung and HT29 colon adenocarcinomas and U1 melanoma. When cells were exposed to 1 microM ouabain prior to and during incubation with doxorubicin, cytotoxicity was markedly reduced. Ouabain had no effect on either the influx or the efflux of doxorubicin. However, all cell lines showed a ouabain-induced decrease in doxorubicin-induced topoisomerase-mediated DNA strand breakage (SSB). These data suggest that blockade of the Na+,K+ pump decreases doxorubicin cytotoxicity in human tumor cells by inhibiting topoisomerase-mediated SSB. Furthermore, they indicate that altered ionic gradients are a potential cause of resistance to drugs that use topoisomerase II as a target.

The dependence of halogenated pyrimidine incorporation and radiosensitization on the duration of drug exposure

The influence of the duration of exposure to the halogenated pyrimidines iododeoxyuridine (IdUrd) and bromodeoxyuridine (BrdUrd) on incorporation into DNA and the resulting radiosensitization was studied in cultured human colon cancer cells. Cells were incubated with either 10 microM BrdUrd or IdUrd for periods up to 7 days. They were also assessed for up to 4 days after removal of drug from the medium. Replacement of thymidine by fraudulent bases was measured using a sensitive gas chromatographic, mass spectrometric (GC/MS) assay. Incorporation of BrdUrd and IdUrd plateaued at 35% and 30%, respectively, after 4 days of exposure. Prolonging the time of exposure to 7 days increased cytotoxicity without affecting either incorporation or radiosensitization. Incorporation remained constant for 1-2 days after removal of drug from the medium. Radiosensitization was linearly related to incorporation throughout the range of conditions assessed. These data suggest that it may be possible to develop a predictive assay for radiosensitization based on measurements of halogenated pyrimidine incorporation in a tumor biopsy specimen. They also suggest that a clinical approach based on repeated short exposures to halogenated pyrimidines may present certain advantages over the current practice of prolonged continuous exposure. A Phase I/II trial using IdUrd and external beam irradiation for the treatment of patients with poor prognosis soft tissue sarcomas has been initiated based on this concept.

Specificity switching of the P1 plasmid centromere-like site

The P1 plasmid partition site acts like a centromere, promoting accurate segregation of copies to daughter cells. A 34 bp segment is essential for partition and binds the plasmid ParB protein. Additional sequences act as specificity elements that direct the choice of copies for partition. They include a second ParB binding site and a site for the host integration host factor protein. Sites lacking one or more of these additional elements are switched to a different specificity. Defined mutants were scored for partition specificity and protein binding. The results suggest that the wild-type site is folded in a specific DNA-protein complex. Disruption of the complex leads to an open configuration which, while still active in partition, has altered recognition specificity.

Delayed treatment with a t-PA analogue and streptokinase in a rabbit embolic stroke model

Fibrinolytic therapy may be effective in the treatment of ischemic stroke, and clinical trials are under way. We evaluated two fibrinolytic agents, an analogue of tissue plasminogen activator (Fb-Fb-CF, the catalytic fragment of the tissue plasminogen activator molecule with a prolonged serum half-life, n = 10) and streptokinase (n = 7), in a rabbit model of embolic stroke. Both agents were given 3 hours after stroke onset, a time relevant to the clinical setting. Fb-Fb-CF was significantly better (p less than 0.04) than saline (n = 7) in restoring blood flow to previously occluded intracranial arteries, but streptokinase was ineffective. Neither fibrinolytic agent was associated with a substantial risk for intracerebral hemorrhagic side effects. Our study demonstrates that Fb-Fb-CF can safely and effectively reperfuse rabbit intracranial arteries 3 hours after occlusion, while streptokinase does not.

Dependence of etoposide-induced cytotoxicity and topoisomerase II-mediated DNA strand breakage on the intracellular ionic environment

We have found that blockade of the Na+,K+-pump by the cardiac glycoside ouabain protects human A549 and hamster V79 cells from the cytotoxic effects of the topoisomerase II poison etoposide. One thousand-fold higher concentrations of ouabain were required to protect V79 cells compared to A549 cells. Since this difference parallels previously measured differences in pump sensitivity, it suggests that protection is mediated directly through pump blockade. Ouabain affected neither the cellular influx nor efflux of etoposide. However, pump blockade did decrease the formation of etoposide-induced DNA-topoisomerase, II-cleavable complexes, assessed as single and double strand DNA breaks using alkaline and neutral elution. To determine if this decrease were a direct effect of change in ionic environment produced by pump blockade, experiments with isolated nuclei and partially purified topoisomerase II were performed. Etoposide-induced cleavable complex formation and topoisomerase-mediated decatenation were assessed in buffers which mimicked either normal intracellular ionic conditions or those produced by ouabain. Compared to the buffer which resembled the normal intracellular ionic conditions, the buffer that mimicked the conditions produced by pump blockade produced fewer etoposide-mediated cleavable complexes in isolated nuclei and less decatenating activity of partially purified topoisomerase II. These findings demonstrate that inhibition of the Na+,K+-pump causes an alteration in the intracellular ionic environment which decreases the activity of topoisomerase II, thus producing a decrease in etoposide-induced cleavable complex formation and cytotoxicity. Since ionic changes occur inside normal cells during progression through the cell cycle as well as in cells that have undergone transformation, these data suggest that the intracellular ionic environment plays a role in determining the sensitivity of normal and malignant cells to this group of chemotherapeutic agents.

A controlled trial of leuprolide with and without flutamide in prostatic carcinoma

To test the hypothesis that maximal androgen blockade improves the effectiveness of the treatment of prostatic cancer, we conducted a randomized, double-blind trial in patients with disseminated, previously untreated prostate cancer (stage D2). All 603 men received leuprolide, an analogue of gonadotropin-releasing hormone that inhibits the release of gonadotropins, in combination with either placebo or flutamide, a nonsteroidal antiandrogen that inhibits the binding of androgens to the cell nucleus. As compared with the 300 patients receiving leuprolide and placebo, the 303 patients randomly assigned to receive leuprolide and flutamide had a longer progression-free survival (16.5 vs. 13.9 months; P = 0.039) and an increase in the median length of survival (35.6 vs. 28.3 months; P = 0.035). The differences between the treatments were particularly evident for men with minimal disease and good performance status; however, further studies should be conducted in this subgroup. Symptomatic improvement was greatest during the first 12 weeks of the combined androgen blockade, when leuprolide alone often produces a painful flare in the disease. We conclude that in patients with advanced prostate cancer, treatment with leuprolide and flutamide is superior to treatment with leuprolide alone.

The association of knee injury and obesity with unilateral and bilateral osteoarthritis of the knee

The strength of the associations of knee injury and obesity with osteoarthritis of the knee was studied for 3,885 adults aged 45-74 years who received knee x-rays in the First National Health and Nutrition Examination Survey, 1971-1975. Bilateral osteoarthritis was more prevalent (5%) than unilateral osteoarthritis (2%). Bilateral osteoarthritis was twice as prevalent in women as in men; however, there was no sex difference in the prevalence of unilateral osteoarthritis. Odds ratios calculated by means of polychotomous logistic regression indicated that obesity, knee injury, and age were significantly associated with both unilateral and bilateral knee osteoarthritis. Obesity was a stronger predictor of bilateral osteoarthritis than was knee injury (odds ratio (OR) = 6.6 for obesity, 3.5 for right knee injury, and 3.0 for left knee injury; 95% confidence interval (CI) 4.71-9.18, 1.80-6.83, and 1.51-6.11, respectively). Knee injury was a stronger predictor of unilateral osteoarthritis than was obesity (OR = 3.4 and 2.4 for obesity in the right and left knee, respectively (95% CI 1.55-7.29 and 0.96-5.75) and OR = 16.3 and 10.9 for injury in the right and left knee, respectively (95% CI 6.50-40.89 and 3.72-31.93]. These findings suggest that different pathogenetic processes may exist for unilateral and bilateral knee osteoarthritis.

Radiopharmaceuticals for radiation synovectomy: evaluation of two yttrium-90 particulate agents

Radiation synovectomy, a noninvasive therapeutic alternative to surgical synovectomy, has not gained widespread acceptance in the United States because of the lack of a suitable radiopharmaceutical. Two new radioactive particles, [90Y]Ca oxalate and [90Y]ferric hydroxide macroaggregates (FHMA), were developed in our laboratory and evaluated for size, stability, and joint leakage. More than 90% of the [90Y]Ca oxalate particles were in the optimal size range of 1-10 microns, and the unbound activity in serum and synovial fluid was 3.7% to 5.0%. Following injection in rabbit knees, leakage of [90Y]Ca oxalate was 5 +/- 2%, with localization primarily in the bone and virtually no uptake by the lymph nodes or liver. Yttrium-90 FHMA particles were larger (95% greater than 10 microns), and at least on a microscopic level, appeared to distribute homogeneously over the articular surface. Leakage of [90Y]FHMA was initially less but eventually slightly exceeded that of [90Y]Ca oxalate. Nevertheless, both radiopharmaceuticals can provide a satisfactory therapeutic dose to the knee with less than half the leakage and a marked reduction in absorbed dose to nontarget tissues compared to previously tested agents. Ease of preparation, physical characteristics of the 90Y beta ray, and apparent lack of substantial leakage from the joint make these agents extremely attractive for clinical evaluation in rheumatoid arthritis patients who are unresponsive to medical therapy.

Selective radiosensitization and cytotoxicity of human melanoma cells using halogenated deoxycytidines and tetrahydrouridine

The halogenated pyrimidines 5-chloro-2'-deoxycytidine (CldCyd) and 5-bromo-2'-deoxycytidine (BrdCyd) can act as radiosensitizers and cytotoxic agents. It was hypothesized that tumor cells and normal cells might use different metabolic pathways to incorporate these halogenated deoxycytidines into DNA. This difference could potentially be exploited to produce selective radiosensitization and cytotoxicity of human tumor cells compared to normal human fibroblasts. This hypothesis was tested using two human melanoma cell lines and two normal fibroblast cell lines. Either CldCyd or BrdCyd alone caused both cytotoxicity and radiosensitization of tumor and normal cells. The addition of the cytidine deaminase inhibitor tetrahydrouridine (H4U) significantly protected the normal cells but had relatively little effect on the tumor cells. These data indicate that it may be possible to exploit differences between the pyrimidine metabolism of normal cells and melanoma cells to improve the therapeutic index of halogenated pyrimidines both as radiosensitizers and as cytotoxic agents.