Mechanical stretch induces hypertrophic responses in cardiac myocytes of angiotensin II type 1a receptor knockout mice

Many lines of evidence have suggested that angiotensin II (AngII) plays an important role in the development of cardiac hypertrophy through AngII type 1 receptor (AT1). To determine whether AngII is indispensable for the development of mechanical stress-induced cardiac hypertrophy, we examined the activity of mitogen-activated protein kinase (MAPK) family and the expression of the c-fos gene as hypertrophic responses after stretching cultured cardiac myocytes of AT1a knockout (KO) mice. When cardiac myocytes were stretched by 20% for 10 min, extracellular signal-regulated protein kinases (ERKs) were strongly activated in KO cardiomyocytes as well as wild type (WT) myocytes. Both basal and stimulated levels of ERKs were higher in cardiomyocytes of KO mice than in those of WT mice. Activation of another member of the MAPK family, p38(MAPK), and expression of the c-fos gene were also induced by stretching cardiac myocytes of both types of mice. An AT1 antagonist attenuated stretch-induced activation of ERKs in WT cardiomyocytes but not in KO cardiomyocytes. Down-regulation of protein kinase C inhibited stretch-induced ERK activation in WT cardiomyocytes, whereas a broad spectrum tyrosine kinase inhibitor (genistein) and selective inhibitors of epidermal growth factor receptor (tyrphostin, AG1478, and B42) suppressed stretch-induced activation of ERKs in KO cardiac myocytes. Epidermal growth factor receptor was phosphorylated at tyrosine residues by stretching cardiac myocytes of KO mice. These results suggest that mechanical stretch could evoke hypertrophic responses in cardiac myocytes that lack the AT1 signaling pathway possibly through tyrosine kinase activation.

Detection and diagnosis of delirium in the elderly: psychiatrist diagnosis, confusion assessment method, or consensus diagnosis?

The clinical diagnosis of delirium has traditionally been based on an assessment by one or more physicians. Because of the transient, ubiquitous, and fluctuating nature of the symptoms of delirium, however, this approach may be flawed. Therefore, we decided to compare diagnosis based on one assessment by a psychiatrist, diagnosis by a nurse clinician (using the Confusion Assessment Method [CAM] and multiple observation points), and diagnosis by consensus. The study subjects were 87 patients aged 65 and over who were admitted consecutively from the emergency department to the medical wards, and who scored 3 or more on the Short Portable Mental Status Questionnaire. All subjects were assessed independently by one of three psychiatrists (a chart review and clinical examination) and a nurse clinician (using the CAM and multiple observation points). A consensus conference, attended by the three psychiatrists and the nurse clinician, used all available information to reach a consensus diagnosis. Compared to the consensus diagnosis, the clinical diagnosis by a psychiatrist had a sensitivity of .73 (95% confidence interval [CI]: .61-.85), a specificity of .93 (95% CI: .79-1.0), and an agreement kappa coefficient of .58 (95% CI: .41-.74). The nurse clinician diagnosis had a sensitivity of .89 (95% CI: .81-.97), a specificity of 1.00, and an agreement kappa coefficient of .86 (95% CI: .75-.97). These results suggest that one clinical assessment by a psychiatrist may not be the best method for detecting and diagnosing delirium in the elderly. A consensus diagnosis or diagnosis by a trained rater (using the CAM and multiple observation points) may be more sensitive approaches.

Hydrophobic forces dominate the thermodynamic characteristics of UvrA-DNA damage interactions

The Escherichia coli DNA repair proteins UvrA, UvrB and UvrC work together to recognize and incise DNA damage during the process of nucleotide excision repair (NER). To gain an understanding of the damage recognition properties of UvrA, we have used fluorescence spectroscopy to study the thermodynamics of its interaction with a defined DNA substrate containing a benzo[a]pyrene diol epoxide (BPDE) adduct. Oligonucleotides containing a single site-specifically modified N2-guanine (+)-trans-, (-)-trans-, (+)-cis-, or (-)-cis-BPDE adducts were ligated into 50-base-pair DNA fragments. All four stereoisomers of DNA-BPDE adducts show an excitation maximum at 350 nm and an emission maximum around 380 to 385 nm. Binding of UvrA to the BPDE-DNA adducts results in a five to sevenfold fluorescence enhancement. Titration of the BPDE-adducted DNA with UvrA was used to generate binding isotherms. The equilibrium dissociation constants for UvrA binding to (+)-trans-, (-)-trans-, (+)-cis-, and (-)-cis- BPDE adduct were: 7.4+/-1.9, 15. 8+/-5.4, 11.3+/-2.7 and 22.4+/-2.0 nM, respectively. There was a large negative change in heat capacity DeltaCpo,obs, (-3.3 kcal mol-1 K-1) accompanied by a relatively unchanged DeltaGoobs with temperature. Furthermore, varying the concentration of KCl showed that the number of ions released upon formation of UvrA-DNA complex is about 3.4, a relatively small value compared to the contact size of UvrA with the substrate. These data suggest that hydrophobic interactions are an important driving force for UvrA binding to BPDE-damaged DNA.

Effective treatment of early endobronchial cancer with regional administration of liposome-p53 complexes

BACKGROUND

Lung cancer originates in a diffusely damaged bronchial epithelium as a result of sequential and cumulative genetic alterations. We investigated the feasibility of in vivo gene replacement in endobronchial precancerous and cancerous cells by a regionally administered nonviral delivery system.

METHODS

After evaluating the in vitro transfection efficiency and cytotoxicity of a variety of cationic liposome-p53 formulations, a specific formulation, DP3-p53, was selected for further in vitro and in vivo evaluation. The ability of DP3-p53 to introduce the p53 gene in the normal bronchial epithelium was studied in transgenic mice that lack the p53 gene. The therapeutic effect of DP3-p53 administered intratracheally was studied in two nude mouse models of endobronchial human lung cancer by use of H358 (p53-null) and H322 (p53-mutant) cells.

RESULTS

DP3-p53 was able to effectively introduce and express the p53 gene and induce G1 arrest and apoptosis in H358 cells in vitro and to introduce and transcribe the p53 gene in the bronchial epithelium of transgenic mice that lack the p53 gene in vivo. In therapeutic experiments using groups of four or five mice each, administration of five intratracheal doses of DP3-p53 (2 microg or 8 microg DNA per dose) on days 4, 8, 12, 16, and 20 after intratracheal tumor inoculation significantly inhibited lung tumor formation and prolonged by approximately twofold the survival of mice bearing H358 or H322 endobronchial tumor cells in contrast to the survival among untreated mice and mice treated with the DP3-empty vector (P = .007 [two-sided logrank test] for mice bearing H358 cells and P = .008 [two-sided logrank test] for those bearing H322 cells).

CONCLUSIONS/IMPLICATIONS

Liposome-based p53 delivery through the airways is a potentially effective strategy for the treatment of early endobronchial cancer. These results have important implications for the gene therapy and prevention of human lung cancer.

[Subcloning and expression of coding region for cellulase binding domain of CBH I from P. janthinellum in E. coli]

The in vitro DNA manipulations, included the nested deletions, of cbh1 from P. janthinellum inserted into pUC18-181 were carried out. The two ends of fragments were modified into blunt ends and the fragments were self-ligated. Then, the encircled plasmids were transformed to E. coli JM109. Utilizing the characterization of CBD binding to crystalline cellulose, one catalytic domain deletion transformant producing active LacZ-CBD fusion protein was isolated from 24 transformants randomly picked from 400 transformants. The molecular weight of the LacZ-CBD fusion protein is 21 kD. The plasmid was designated pUC 18C. The LacZ-CBD fusion protein produced by JM109(pUC18C) was able to be purified by procedure of adsorption-desorption to cellulose. The pNPC activity of crude enzyme solution of JM109(pUC18C) induced by IPTG were zero, identified the JM109(pUC18C) has no CBHI activity.

Evaluation of ocular safety: tirapazamine plus cisplatin in patients with metastatic melanomas

Ninety-six patients with metastatic melanoma treated with two consecutive tirapazamine-cisplatin combination chemotherapy regimens were followed for signs of therapy-related ocular toxicity. Baseline and follow-up data were obtained such that each patient acted as his own control. A battery of vision-related tests was performed. These included: best corrected visual acuity, color vision, retinal fundus examination and electro-oculograms (EOG). A brief health-related quality of vision test was administered at each follow-up visit to detect and evaluate self-perceived changes in visual status. In the first study, 48 patients received i.v. tirapazamine over 2 h at 260 mg/m2 (group 1) while in the second study 48 patients (group 2) received i.v. tirapazamine at 390 mg/m2. Visual system assessment was conducted at three timepoints: first at baseline, then at 6 weeks post-baseline, i.e. after two courses of chemotherapy and visit two upon discontinuation of therapy. There was no difference in visual acuity between group 1 and group 2 at baseline, follow-up 1 or at follow-up 2. Grouped data indicate that visual acuity was not affected by either dosage of chemotherapy. Group 1 at baseline found 15% below the normal EOG cutoff point, increasing to 23% at follow-up 1 and increasing at follow-up visit 2 to 33%. Group 2 demonstrated the same EOG findings, but the results were more magnified: baseline, 24%; follow-up 1, 44%; and follow-up 2, 44%. After eliminating those with abnormal color vision baselines, 21% (nine of 42) group 1 patients demonstrated abnormal color vision total error scores at follow-up 1 and 16.7% (four of 24) at follow-up 2. Few individuals showed changes in the higher dosage group. With the exception of one person in each dosage group, all changes were along the blue-yellow (tritan) axis, which is associated with acquired color defects. Of 96 patients examined, proven fundus changes were found in only four subjects. These fundus findings included retinal hemorrhages, retinal nerve fiber layer infarcts (cotton wool spots) and small retinal pigment epithelium detachments. There was no systematic statistical significant difference among the various measures of visual system outcome between groups or test times. Data from all tests for individual patients in both groups reveals a sporadic distribution of changes in visual system tests. If toxicity were pronounced, one would expect consistency in the findings and all or most of the assessment tests would be abnormal for a particular patient. However, patients who were abnormal on one measure of acuity were not necessarily abnormal on the other measures.

Mapper: an intelligent restriction mapping tool

MOTIVATION

To determine the most powerful artificial intelligence techniques for automated restriction mapping, and use them to create a powerful multiple-enzyme restriction mapping tool.

RESULTS

The most effective search engine utilized model-driven exhaustive search and a form of binary logic pruning based on Pratt's separation theory. Additional experimentation led to the development of an input preprocessing module which significantly speeds up searches, and an output post-processing module which enables users to analyze large solution sets and reduce their apparent complexity.

AVAILABILITY

An executable version of the resultant tool, Mapper, can be downloaded from our Web site (http://www.ai.eecs.uic.edu) by selecting the 'Software' option.

CONTACT

nelson@eecs.uic.edu (http://www.ai.eecs.uic.edu/ñelson).

Involvement of molecular chaperonins in nucleotide excision repair. Dnak leads to increased thermal stability of UvrA, catalytic UvrB loading, enhanced repair, and increased UV resistance

UvrA is one of the key Escherichia coli proteins involved in removing DNA damage during the process of nucleotide excision repair. The relatively low concentrations (nanomolar) of the protein in the normal cells raise the potential questions about its stability in vivo under both normal and stress conditions. In vitro, UvrA at low concentrations is shown to be stabilized to heat inactivation by E. coli molecular chaperones DnaK or the combination of DnaK, DnaJ, and GrpE. These chaperone proteins allow sub-nanomolar concentrations of UvrA to load UvrB through >10 cycles of incision. Guanidine hydrochloride-denatured UvrA was reactivated by DnaK, DnaJ, and GrpE to as much as 50% of the native protein activity. Co-immunoprecipitation assays showed that DnaK bound denatured UvrA in the absence of ATP. UV survival studies of a DnaK-deficient strain indicated an 80-fold increased sensitivity to 100 J/m2 of ultraviolet light (254 nm) as compared with an isogenic wild-type strain. Global repair analysis indicated a reduction in the extent of pyrimidine dimer and 6-4 photoproduct removal in the DnaK-deficient cells. These results suggest that molecular chaperonins participate in nucleotide excision repair by maintaining repair proteins in their properly folded state.

Signal transduction in arteriosclerosis: mechanical stress-activated MAP kinases in vascular smooth muscle cells (review)

Vascular smooth muscle cell (SMC) proliferation is a key event in the development of (spontaneous) atherosclerosis, hypertension-related arteriosclerosis, angioplasty-induced restenosis and venous bypass graft arteriosclerosis. Many factors or environmental stimuli are believed to be responsible for SMC growth or hypertrophy in the vessel wall. How these environmental stimuli or signals applied onto the surface of SMCs are transduced into the cell nucleus resulting in quantitative and qualitative changes in gene expression in SMCs of arterial walls is largely unknown. Mitogen-activated protein (MAP) kinases are rapidly activated in cells stimulated with various extracellular signals by dual phosphorylation of tyrosine and threonine residues. They are thought to play a pivotal role in transmitting transmembrane signals required for cell growth and differentiation. Recent studies have focused on the signalling events in vascular tissues in vivo and in cultured SMCs in vitro. It has been demonstrated that acute hypertension and angioplasty rapidly induced MAP kinase activation in the arterial wall. Kinase activation is followed by an increase in c-fos and c-jun gene expression and enhanced transcription factor AP-1 DNA-binding activity. A similar MAP kinase activation can be mimicked in in vitro cultured SMCs stimulated by either shear stress or cyclic strain stretch, suggesting direct effects of mechanical force. Interestingly, physical forces rapidly resulted in phosphorylation of platelet-derived growth factor (PDGF) receptor, an activated state, in cultured SMCs. Thus, mechanical stresses may directly perturb the cell surface or alter receptor conformation, thereby initiating signalling pathways usually used by growth factors. These findings have significantly enhanced our knowledge concerning the pathogenesis of arteriosclerosis and provide a basis for therapeutic intervention on vascular diseases.

Acute pressure overload could induce hypertrophic responses in the heart of angiotensin II type 1a knockout mice

Increasing evidence has suggested that locally produced angiotensin II (Ang II) plays an important role in the development of cardiac hypertrophy through the Ang II type 1 receptor (AT1). We and others have recently reported that Ang II is critical for mechanical stress-induced hypertrophic responses in vitro. Using AT1a knockout (KO) mice, we examined whether Ang II is indispensable for pressure overload-induced cardiac hypertrophy in the present study. Reverse-transcriptase polymerase chain reaction analysis revealed that AT1 mRNA levels were <10% in the heart of KO mice compared with wild-type (WT) mice, but the Ang II type 2 receptor gene was expressed at almost the same levels in the hearts of both mice. Intravenous infusion of subpressor dose of Ang II induced c-fos gene expression in the hearts of WT mice but not KO mice. Acute pressure overload, however, induced expressions of immediate-early response genes and activations of mitogen-activated protein kinases in the hearts of KO mice as well as WT mice. Both basal and activated levels of all these responses were significantly higher in KO mice than in WT mice. Pressure overload markedly increased the heart weight-to-body weight ratio in both mice strains at 14 days after aortic banding. These results suggest that acute hypertrophic responses could be induced by pressure overload in the in vivo heart without AT1 signaling.

[Polymorphism analysis of 4 loci of X-chromosome in a Chinese population of the Han nationality]

OBJECTIVE

To investigate the polymorphism of 4 loci of X-chromosome in the Hans.

METHODS

Using PCR-SSLP, the authors analysed the polymorphism of DXS1068, DXS7132, DXS6804 and DXS6799 in the X-chromosome in 70 randomly selected female Hans.

RESULTS

The number of alleles in the 4 loci were 5,5,5 and 6 respectively; there were no significant differences between the observed and estimated and genotype probabilities of the 4 loci; the estimates of heterozygosity of 4 loci were 0.6819, 0.6895, 0.7659 and 0.6483 respectively and there were no significant differences between the observed and estimated heterozygosity of the 4 loci.

CONCLUSION

The distribution of alleles and genotype probabilities of 4 loci all observe the Hardy-Weinberg equilibrium.

Role of ion channels and exchangers in mechanical stretch-induced cardiomyocyte hypertrophy

We have previously reported that stretching of cardiomyocytes activates the phosphorylation cascade of protein kinases, including Raf-1 kinase and mitogen-activated protein (MAP) kinases, followed by an increase in protein synthesis partly through enhanced secretion of angiotensin II and endothelin-1. Membrane proteins, such as ion channels and exchangers, have been postulated to first receive extracellular stimuli and evoke intracellular signals. The present study was performed to determine whether mechanosensitive ion channels and exchangers are involved in stretch-induced hypertrophic responses. Neonatal rat cardiomyocytes cultured on expandable silicone dishes were stretched after pretreatment with a specific inhibitor of stretch-sensitive cation channels (gadolinium and streptomycin), of ATP-sensitive K+ channels (glibenclamide), of hyperpolarization-activated inward channels (CsCl), or of the Na+-H+ exchanger (HOE 694). Pretreatment with gadolinium, streptomycin, glibenclamide, and CsCl did not show any inhibitory effects on MAP kinase activation by mechanical stretch. HOE 694, however, markedly attenuated stretch-induced activation of Raf-1 kinase and MAP kinases by approximately 50% and 60%, respectively, and attenuated stretch-induced increase in phenylalanine incorporation into proteins. In contrast, HOE 694 did not inhibit angiotensin II-and endothelin-1-induced Raf-1 kinase and MAP kinase activation. These results suggest that among many mechanosensitive ion channels and exchangers, the Na+-H+ exchanger plays a critical role in mechanical stress-induced cardiomyocyte hypertrophy.

Effect of cataract surgery on ocular axial length elongation in young children

PURPOSE

To evaluate the influence of cataract surgery on eyes of children between 1-5 years old.

MATERIALS AND METHODS

Forty-seven cases of pediatric cataract, including 31 cases of bilateral congenital cataract and 16 cases of unilateral posttraumatic cataract, were retrospected. Of the 31 cases of congenital cataract, 19 cases (group 1) had undergone cataract extraction with intraocular lens (IOL) implantation, 12 (group 2) had undergone cataract extraction without IOL implantation. Each of them had their two eyes operated separately at an interval of 1 year or longer. Of the 16 cases of posttraumatic cataract, 6 (group 3) had undergone cataract extraction with IOL implantation and 10 (group 4) had undergone cataract extraction without IOL implantation. Mean age at the time of interested surgery was 2.9 years (range from 1.1 to 5.1 years). Ocular axial length of both eyes measured by A-scan ultrasonography before and after the surgery of the earlier operated eye in the congenital groups and the operated eye in the post-traumatic groups was recorded. The elongation of axial length of the earlier operated eye in the congenital groups and the operated eyes in the posttraumatic groups of each case were compared with that of the fellow eye statistically with paired t-test.

RESULTS

The mean follow-up was 2.6 years (ranged from 1.0 to 6.4 years). In all the 4 groups, the elongation of axial length between the earlier operated eye and later operated eye in the congenital groups and between the operated and unoperated eyes in the posttraumatic groups of each case was not significantly different (p > 0.05).

CONCLUSION

Cataract surgery, either extraction with or without IOL implantation, did not retard axial elongation in children above 1 year old.

[Analysis of chemical components from Pheretima]

The total fat, total nitrogens, free amino acids, inorganic elements of Pheretima have been determined. It will provide scientific evidence for the establishment of quality standards of pheretima.

Cell type-specific angiotensin II-evoked signal transduction pathways: critical roles of Gbetagamma subunit, Src family, and Ras in cardiac fibroblasts

Angiotensin II (Ang II) induces hypertrophy of cardiac myocytes and hyperplasia of cardiac fibroblasts. To determine the molecular mechanism by which Ang II displayed different effects on cardiac myocytes and fibroblasts, we examined signal transduction pathways leading to activation of extracellular signal-regulated kinases (ERKs). Ang II-induced ERK activation was abolished by pretreatment with pertussis toxin and by overexpression of the Gbetagamma subunit-binding domain of the beta-adrenergic receptor kinase 1 in cardiac fibroblasts but not in cardiac myocytes. Inhibition of protein kinase C strongly inhibited activation of ERKs by Ang II in cardiac myocytes, whereas inhibitors of tyrosine kinases but not of protein kinase C abolished Ang II-induced ERK activation in cardiac fibroblasts. Overexpression of C-terminal Src kinase (Csk), which inactivates Src family tyrosine kinases, suppressed the activation of transfected ERK in cardiac fibroblasts. Ang II rapidly induced phosphorylation of Shc and association of Shc with Grb2. Cotransfection of the dominant-negative mutant of Ras or Raf-1 kinase abolished Ang II-induced ERK activation in cardiac fibroblasts. Overexpression of Csk or the dominant-negative mutant of Ras had no effects on Ang II-induced ERK activation in cardiac myocytes. These findings suggest that Ang II-evoked signal transduction pathways differ among cell types. In cardiac fibroblasts, Ang II activates ERKs through a pathway including the Gbetagamma subunit of Gi protein, tyrosine kinases including Src family tyrosine kinases, Shc, Grb2, Ras, and Raf-1 kinase, whereas Gq and protein kinase C are important in cardiac myocytes.

Efficient inhibition of the development of cardiac remodeling by a long-acting calcium antagonist amlodipine

The purpose of the present study was to examine the effects of a long-acting calcium antagonist, amlodipine, on the development of cardiac remodeling. Dihydropyridine calcium antagonists have been used widely for many years in the treatment of hypertension and angina pectoris. It has been reported, however, that a prototype of dihydropyridines, nifedipine, does not reduce mortality of patients with ischemic heart disease, possibly because of reflex stimulation of the sympathetic nervous system. A calcium antagonist, amlodipine, has been reported to have potential benefits by virtue of a gradual onset of action and a long duration of effects. Amlodipine (8 mg/kg per day, once a day) or nifedipine (24 mg/kg per day, three times a day) was administered to spontaneously hypertensive 12-week-old rats for 12 weeks. Left ventricular wall thickness was measured by echocardiography, and relative amounts of myosin heavy chain isoforms were assessed by pyrophosphate gels. Expressions of "fetal type" genes and type 1 collagen gene were examined by Northern blot analysis. Amlodipine and nifedipine both markedly reduced systolic blood pressure. However, the decrease in systolic blood pressure caused by nifedipine continued for no more than 8 hours, whereas the blood pressure-lowering effect of amlodipine continued for more than 16 hours post dose. Amlodipine markedly reduced left ventricular wall thickness, whereas nifedipine only weakly attenuated an increase in the wall thickness. Amlodipine, but not nifedipine, prevented an increase in the relative amount of V3 myosin heavy chain isoform and suppressed an increase in mRNA levels of beta-myosin heavy chain, skeletal alpha-actin, and type 1 collagen. Unlike nifedipine, amlodipine effectively prevented cardiac remodeling secondary to high blood pressure at biochemical levels and morphological levels. These results suggest that a long-acting calcium antagonist is more effective than a short-acting one in preventing organ injury in hypertensive subjects.

Abundance of platelet-derived growth factors (PDGFs), PDGF receptors and activation of mitogen-activated protein kinases in brain decline with age

Platelet-derived growth factors (PDGFs) specifically bind to PDGF receptors (PDGFRs), resulting in their activation via autophosphorylation and subsequent triggering of a cascade of phosphorylation events that include mitogen-activated protein (MAP) kinases. Most of our knowledge concerning MAP kinase activation comes from studies of cultured cells in vitro, and little is known about their activation in vivo. In the present study, we determined PDGF and PDGFR levels and MAP kinase activities, including extracellular signal-regulated protein kinases (ERK) and c-Jun NH2-terminal protein kinases (JNK) or stress-activated protein kinases (SAPK) in brain of young and older mice. Both PDGF and PDGFR proteins were most abundant in protein extracts from brain (cerebral cortex) among tissues of heart, liver, spleen, lung and kidney, as determined by Western blot analysis. PDGFR proteins in brain differed significantly between young (1 or 8 weeks) and older (14 months) mice and PDGFR phosphorylation was seen in all age groups examined by a specific antibody against phosphotyrosine. The highest activity ERK2 was also observed in brain tissues, and this activity declined with age, although ERK1 and ERK2 protein levels were not significantly altered during development and aging. Furthermore, the activity and amount of JNK/SAPK proteins were the most abundant in brain tissues and did not change with age. Thus, our findings demonstrate that the highest levels of PDGFs and PDGFRs existed in brain, and constitutive activation of MAP kinases declined with age, suggesting that signal pathways mediated by PDGF-MAP kinase cascades are important components in coordinating growth and differentiation of neurone and glial cells during development and aging.

[Study on substance P immunoreactivity after acute crush injury to facial nerve]

This paper presents the change in substance P immunoreactivity (SP-IR) after acute crush injury to the vertical part of facial nerve of normal cats by using immunohistochemical and immunocytochemical techniques combined with immunoelectronic microscopy. The electroneuromyogram (ENOG) shows that the cats have suffered from fully peripheral facial paralysis. It is found that the SP-IR positive products and fibers increase in the other part of facial nerve (including the non-injured part of vertical segment and level segment) after injury, especially six days later. As a result, it is suggested that the regeneration and repair of facial nerve might be in close relationship with substance P after acute crush injury to it.

A precise interchromosomal reciprocal exchange between hot spots for cleavable complex formation by topoisomerase II in amsacrine-treated Chinese hamster ovary cells

Among the aprt mutations induced in confluence-arrested Chinese hamster ovary D422 cells by the topoisomerase II poison amsacrine, there was a reciprocal exchange between the aprt gene and an unrelated sequence, accompanied by a chromosomal translocation at the aprt locus. The breakpoints in both parental sequences were hot spots for amsacrine-stimulated DNA cleavage in vitro, and the novel junctions formed were precisely as expected for a mechanism involving reciprocal exchange of topoisomerase II subunits followed by resealing of the breaks and correction of mismatches in the cohesive ends. The results are consistent with a role for direct subunit exchange in the production of chromosomal translocations by topoisomerase poisons, although more complex models involving double-strand breakage and repair could produce reciprocal exchanges of similar specificity.

Highly conservative reciprocal translocations formed by apparent joining of exchanged DNA double-strand break ends

Chromosomal translocations induced by ionizing radiation and radiomimetic drugs are thought to arise by incorrect joining of DNA double-strand breaks. To dissect such misrepair events at a molecular level, large-scale, bleomycin-induced rearrangements in the aprt gene of Chinese hamster ovary D422 cells were mapped, the breakpoints were sequenced, and the original non-aprt parental sequences involved in each rearrangement were recovered from nonmutant cells. Of seven rearrangements characterized, six were reciprocal exchanges between aprt and unrelated sequences. Consistent with a mechanism involving joining of exchanged double-strand break ends, there was, in most cases, no homology between the two parental sequences, no overlap in sequences retained at the two newly formed junctions, and little or no loss of parental sequences (usually Collapse

Key Words

• bleomycin
• nonhomologous recombination
• dna repair
• dna end-joining
• gene rearrangements

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MESH Headings

• Adenine Phosphoribosyltransferase/genetics
• Animals
• Base Sequence
• Bleomycin/pharmacology
• CHO Cells
• Cricetinae
• DNA Damage
• Free Radicals
• Gene Rearrangement
• In Situ Hybridization, Fluorescence
• Molecular Sequence Data
• Mutagenesis
• Mutagens/pharmacology
• Recombination, Genetic
• Sequence Analysis, DNA
• Translocation, Genetic

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Grants

• R01 CA040615 NCI NIH HHS
• HD33527 NICHD NIH HHS
• CA40615 NCI NIH HHS

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Oxidative stress activates extracellular signal-regulated kinases through Src and Ras in cultured cardiac myocytes of neonatal rats

A growing body of evidence has suggested that oxidative stress causes cardiac injuries during ischemia/reperfusion. Extracellular signal-regulated kinases (ERKs) have been reported to play pivotal roles in many aspects of cell functions and to be activated by oxidative stress in some types of cells. In this study, we examined oxidative stress-evoked signal transduction pathways leading to activation of ERKs in cultured cardiomyocytes of neonatal rats, and determined their role in oxidative stress-induced cardiomyocyte injuries. ERKs were transiently and concentration-dependently activated by hydrogen peroxide (H2O2) in cardiac myocytes. A specific tyrosine kinase inhibitor, genistein, suppressed H2O2-induced ERK activation, while inhibitors of protein kinase A and C or Ca2+ chelators had no effects on the activation. When CSK, a negative regulator of Src family tyrosine kinases, or dominant-negative mutant of Ras or of Raf-1 kinase was overexpressed, activation of transfected ERK2 by H2O2 was abolished. The treatment with H2O2 increased the number of cells stained positive by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and induced formation of DNA ladder and activation of CPP32, suggesting that H2O2 induced apoptosis of cardiac myocytes. When H2O2-induced activation of ERKs was selectively inhibited by PD98059, the number of cardiac myocytes which showed apoptotic death was increased. These results suggest that Src family tyrosine kinases, Ras and Raf-1 are critical for ERK activation by hydroxyl radicals and that activation of ERKs may play an important role in protecting cardiac myocytes from apoptotic death following oxidative stress.

Protein kinase A and protein kinase C synergistically activate the Raf-1 kinase/mitogen-activated protein kinase cascade in neonatal rat cardiomyocytes

Adrenoceptor agonists play an important role in cardiac hypertrophy. In cardiomyocytes, activation of alpha- and beta-adrenoceptors induces a variety of hypertrophic responses via activation of protein kinase C (PKC) and protein kinase A (PKA), respectively. Although PKC evokes activation of the Raf-1 kinase (Raf-1)/mitogen-activated protein (MAP) kinase cascade, PKA has been shown to inhibit the activation of Raf-1 and MAP kinases induced by growth factors in various cell types. The present study was performed to elucidate the role of PKA and PKC in cardiomyocyte hypertrophy. PKA activators such as forskolin (FSK), isobutylmethylxanthine, dibutyryl cAMP and isoproterenol, significantly activated Raf-1 and MAP kinases with a peak at 2 and 8 min, respectively, followed by an increase in protein synthesis in cardiac myocytes. Similar responses were observed when cardiomyocytes were stimulated with PKC activators such as 12-O-tetradecanoylphorbol-13-acetate (TPA), angiotensin II, phenylephrine and mechanical stretch. After depleting extracellular Ca2+ with EGTA, FSK did not activate MAP kinases, while down-regulation of PKC by long exposure with TPA did not influence FSK-induced MAP kinase activation. Furthermore, FSK and TPA synergistically activated Raf-1. Similar synergistic activation of MAP kinases was observed when other PKC activators were added to cardiac myocytes with FSK at the same time. In conclusion, unlike other cell types, PKA activates Raf-1 and MAP kinases followed by an increase in protein synthesis in cardiac myocytes.

[Protection of hepatocyte growth factor against carbon tetrachloride injury in primary rat hepatocyte culture]

The protective effect of recombinant human hepatocyte growth factor (r-hHGF) against carbon tetrachloride (CCl4) injury in cultured rat hepatocytes was investigated. It was found that r-hHGF had cytoprotective effect on hepatocytes anainst CCl4 poisoning. Pretreatment with r-hHGF significantly increased the viability of cultured hepatocytes, reduced the leakage of intracellular alanine transaminase and potassium into the culture medium, as compared with the CCl4 group. The results suggest that r-hHGF may protect hepatocytes against CCl4 injury through lessening the severity of membrane lesion, preventing intracellular alanine transaminase and potassium leakage and sustaining the integrity of hepatocyte membrane.

Risk factors for bladder cancer: a case-control study in northeast China

A case-control study of risk factors for bladder cancer was carried out in Heilongjing Province, China. Between May 1989 and May 1990, 217 histologically confirmed cases of bladder cancer and 254 controls with non-neoplastic and non-urine system disease were recruited. Individuals were interviewed in the wards of six major hospitals. Controls were matched by sex, age and area of residence. Information was collected concerning economic status, occupation, histories of smoking and consumption of alcohol, use of tea, the taking of analgesics, dietary histories and previous diseases. Odds ratios (ORs) were calculated from stratified analysis and conditional logistic regression models. Increased risk was observed with increasing times per year and number of years of saccharine use. Compared with non-users, the use of saccharine for more than 19 times per year, and for more than 15 years, the adjusted ORs were 3.9 (95% CI = 1.8-8.67) and 5.1 (95% CI = 2.3-11.6), respectively. Statistically significant associations were also found for diseases related to the urinary system (OR = 2.8; 95% CI = 1.1-7.6). Increased consumption of fruit and vegetable may reduce the risk of bladder cancer. Cigarette smoking had no effect on the risk of bladder cancer in both genders. There was no association between the consumption of alcohol or tea, or types of water supply, with bladder cancer risk.

Genetic diversity analysis by RAPD inCathaya argyrophylla Chun et Kuang

Genetic diversity level ofCathaya argyrophylla was confirmed by random amplified polymorphic DNA (RAPD) markers. Seventy five samples (individuals), collected from Hunan and Sichuan provinces of China were used in the study. 21 10-mer oligonucleotide primers detected 106 sites, and 34 (32%) of them were polymorphic. The level of genetic variation in C.argyrophylla was lower than those of other conifers, and was considered to be associated with the complexity of habitats. The percentages of polymorphic sites (PPS) in the Hunan and Sichuan populations were 18% and 25% respectively. 7.99% of genetic variation existed between the two populations; this value was higher than the mean value (6.8%) among populations in conifers displayed by allozyme. Some subpopulations ofC. argyrophylla were greatly differentiated because of site mutation and genetic drift. The highest value of genetic difference between subpopulations amounted to 16. 23%. In addition, a concept of diversity coefficient (DC), a value used to measure the genetic diversity level, and its calculation were proposed. The low genetic diversity level ofC. argyrophylla was thought to be one of the factors causing its endangered status.

Annamycin circumvents resistance mediated by the multidrug resistance-associated protein (MRP) in breast MCF-7 and small-cell lung UMCC-1 cancer cell lines selected for resistance to etoposide

Annamycin (Ann) is a highly lipophilic anthracycline antibiotic that has been shown to circumvent MDR-1 both in vitro and in vivo. A liposomal formulation of Ann is currently in phase I clinical trials. The multidrug resistance-associated protein (MRP) has been found to be over-expressed in some human leukemias at relapse and to be a poor prognostic factor in neuroblastoma. We studied the in vitro cytotoxicity and the cellular uptake and efflux of Ann and doxorubicin (Dox) in 2 pairs of human cell lines, breast carcinoma MCF7 and small-cell lung cancer UMCC-1, and their MRP-expressing counterparts, MCF-7/VP and UMCC-1/VP. Resistance indexes were 1.1 and 1.4 for Ann vs. 6.9 and 11.6 for Dox. Ann cellular accumulation was 3- to 5-fold higher than that of Dox in both sensitive and resistant cells. No changes in drug efflux between sensitive and resistant cells were observed in the case of Ann, while Dox efflux at 1 hr was 20-25% higher in resistant than in sensitive cells. By confocal microscopy, the subcellular distribution of Ann was identical in sensitive and resistant cells, localizing mostly in the perinuclear structures, while that of Dox was exclusively nuclear in sensitive cells and nuclear and in the cell membrane in resistant cells. There was a good correlation between the extent of DNA breaks induced by each drug in the different cell lines and cytotoxic effect. Our results indicate that Ann may be effective in the treatment of malignancies in which MRP is a relevant mechanism of clinical resistance.

Norepinephrine induces the raf-1 kinase/mitogen-activated protein kinase cascade through both alpha 1- and beta-adrenoceptors

BACKGROUND

Although norepinephrine induces cardiac hypertrophy by activating protein kinase A and C through beta- and alpha 1-adrenoceptors, respectively, protein kinase A has been reported to inhibit cell growth in many other cell types.

METHODS AND RESULTS

To elucidate the molecular mechanism of norepinephrine-induced hypertrophic responses, we examined the effects of protein kinase A and protein kinase C on the activities of raf-1 kinase and mitogen-activated protein (MAP) kinases and on protein synthesis rates using cultured cardiomyocytes of neonatal rats. Norepinephrine-induced activation of MAP kinases was partially inhibited by either an alpha 1-adrenoceptor blocker (prazosin) or a beta-adrenoceptor blocker (propranolol) and was completely abolished by both blockers. Both a beta-adrenoceptor agonist, isoproterenol, and an alpha 1-adrenoceptor agonist, phenylephrine, increased the activities of raf-1 kinase and MAP kinases and phenylalanine incorporation into proteins. Furthermore, isoproterenol and phenylephrine synergistically activated these kinases and protein synthesis. Similar synergistic activation of MAP kinases was observed when other protein kinase A-activating agents such as forskolin, dibutyryl cAMP, and isobutyl-methylxanthine were used with a protein kinase C-activating agent at the same time. Chelation of extracellular Ca2+ completely abolished isoproterenol- and phenylephrine-evoked MAP kinase activation.

CONCLUSIONS

Norepinephrine activates the raf-1 kinase/MAP kinase cascade through both alpha 1- and beta-adrenergic stimulation, and signaling pathways from the two receptors synergistically induce cardiomyocyte hypertrophy.

Non-trans-scleral suture fixation of posterior chamber intraocular lenses in the absence of posterior capsular support

PURPOSE

To develop a new technique for fixation of posterior chamber intraocular lens (IOL) in the absence of posterior capsule support.

MATERIALS AND METHODS

We performed non-trans-scleral fixation of intraocular lenses on 24 cases (24 eyes) without posterior capsule support. Two scleral flaps with limbal incisions and two peripheral iridectomies were made at 1 o'clock and 7 o'clock positions respectively. A suture-leading needle was used to lead the prolene suture from the limbal incision and iridectomy on one side through the iridectomy and limbal incision on the other side. Intraocular lens (IOL) was then fixed in the ciliary sulcus.

RESULTS

After a mean follow-up of 6.6 months (range from 3 to 14 months), corrected visual acuity of 16 cases (16 eyes, 66.7%) got 0.5 or better. Postoperative complications included discoria (4 eyes), surface membrane formation (1 eye), choroidal detachment (1 eye) and tilt of IOL (1 eyes), but all were not severe.

CONCLUSION

In some situations such as low intraocular pressure, non-penetration scleral fixation may be a good way to implant IOL in the absence of posterior capsule support.

Formation of DNA repair intermediates and incision by the ATP-dependent UvrB-UvrC endonuclease

The Escherichia coli UvrB and UvrC proteins play key roles in DNA damage processing and incisions during nucleotide excision repair. To study the DNA structural requirements and protein-DNA intermediates formed during these processes, benzo[a]pyrene diol epoxide-damaged and structure-specific 50-base pair substrates were constructed. DNA fragments containing a preexisting 3' incision were rapidly and efficiently incised 5' to the adduct. Gel mobility shift assays indicated that this substrate supported UvrA dissociation from the UvrB-DNA complex, which led to efficient incision. Experiments with a DNA fragment containing an internal noncomplementary 11-base region surrounding the benzo[a]pyrene diol epoxide adduct indicated that UvrABC nuclease does not require fully duplexed DNA for binding and incision. In the absence of UvrA, UvrB (UvrC) bound to an 11-base noncomplementary region containing a 3' nick (Y substrate), forming a stable protein-DNA complex (Kd approximately 5-10 nM). Formation of this complex was absolutely dependent upon UvrC. Addition to this complex of ATP, but not adenosine 5'-(beta,gamma-iminotriphosphate) or adenosine 5'-(beta, gamma-methylene)triphosphate, caused incision three or four nucleotides 5' to the double strand-single strand junction. The ATPase activity of native UvrB is activated upon interaction with UvrC and enhanced further by the addition of Y substrate. Incision of this Y structure occurs even without DNA damage. Thus the UvrBC complex is a structure-specific, ATP-dependent endonuclease.

CARP, a cardiac ankyrin repeat protein, is downstream in the Nkx2-5 homeobox gene pathway

To identify the molecular pathways that guide cardiac ventricular chamber specification, maturation and morphogenesis, we have sought to characterize factors that regulate the expression of the ventricular myosin light chain-2 gene, one of the earliest markers of ventricular regionalization during mammalian cardiogenesis. Previously, our laboratory identified a 28 bp HF-la/MEF-2 element in the MLC-2v promoter region, which confers cardiac ventricular chamber-specific gene expression during murine cardiogenesis, and showed that the ubiquitous transcription factor YB-1 binds to the HF-la site in conjunction with a co-factor. In a search for interacting co-factors, a nuclear ankyrin-like repeat protein CARP (cardiac ankyrin repeat protein) was isolated from a rat neonatal heart cDNA library by yeast two-hybrid screening, using YB-1 as the bait. Co-immunoprecipitation and GST-CARP pulldown studies reveal that CARP forms a physical complex with YB-1 in cardiac myocytes and immunostaining shows that endogenous CARP is localized in the cardiac myocyte nucleus. Co-transfection assays indicate that CARP can negatively regulate an HF-1-TK minimal promoter in an HF-1 sequence-dependent manner in cardiac myocytes, and CARP displays a transcriptional inhibitory activity when fused to a GAL4 DNA-binding domain in both cardiac and noncardiac cell context. Northern analysis revealed that carp mRNA is highly enriched in the adult heart, with only trace levels in skeletal muscle. During murine embryogenesis, endogenous carp expression was first clearly detected as early as E8.5 specifically in heart and is regulated temporally and spatially in the myocardium. Nkx2-5, the murine homologue of Drosophila gene tinman was previously shown to be required for heart tube looping morphogenesis and ventricular chamber-specific myosin light chain-2 expression during mammalian heart development. In Nkx2-5(−/−)embryos, carp expression was found to be significantly and selectively reduced as assessed by both whole-mount in situ hybridizations and RNase protection assays, suggesting that carp is downstream of the homeobox gene Nkx2-5 in the cardiac regulatory network. Co-transfection assays using a dominant negative mutant Nkx2-5 construct with CARP promoter-luciferase reporter constructs in cardiac myocytes confirms that Nkx2-5 either directly or indirectly regulates carp at the transcriptional level. Finally, a carp promoter-lacZ transgene, which displays cardiac-specific expression in wild-type and Nkx2-5(+/−) background, was also significantly reduced in Nkx2-5(−/−) embryos, indicating that Nkx2-5 either directly or indirectly regulates carp promoter activity during in vivo cardiogenesis as well as in cultured cardiac myocytes. Thus, CARP is a YB-1 associated factor and represents the first identified cardiac-restricted downstream regulatory gene in the homeobox gene Nkx2-5 pathway and may serve as a negative regulator of HF-1-dependent pathways for ventricular muscle gene expression.

[Effects of hepatocyte growth factor on dose- and time-response of DNA synthesis in rat hepatocytes in vitro]

Effects of recombinant human hepatocyte growth factor (r-hHGF) on dose- and time-response of DNA synthesis were observed by using the method of 3H-TdR incorporation into DNA in rat hepatocytes in vitro. The results showed that r-hHGF was the most potent mitogen for initiating DNA synthesis of hepatocytes, and there were dose-dependent increase in the range of 1 ng/ml (10 pmol/L)-10 ng/ml (100 pmol/L). The significant effect of r-hHGF was observed even at 1 ng/ml, and the maximal stimulatory effect was found at 10 ng/ml, which was 7-fold rise than the control. Beyond 10 ng/ml, r-hHGF inhibited hepatocyte DNA synthesis. In addition, time-response of r-hHGF on DNA synthesis was observed at 24 h, 48 h, 72 h and 96 h respectively, 3H-thymidine incorporation was higher than control group after 24 hours of incubation with r-hHGF, and reached top at 48 hours. DNA synthesis decreased after 72 and 96 hours of incubation with r-hHGF.

Angiotensin II stimulates c-Jun NH2-terminal kinase in cultured cardiac myocytes of neonatal rats

Many lines of evidence have suggested that angiotensin II (Ang II)plays an important role in cardiac hypertrophy. Ang II not only increases protein synthesis but also induces the reprogramming of gene expression in cultured cardiac myocytes. In the present study, to elucidate the mechanism by which Ang II regulates gene expression in cardiac myocytes, we examined whether Ang II activates c-Jun NH2-terminal kinase (JNK), which is a member of the mitogen-activated protein kinase family and activates the transcription factor, activator protein-1 (AP-1). The activity of JNK increased 5 minutes after the addition of Ang II, peaked at 20 minutes, and gradually decreased thereafter. Examination of the Ang II dose-response relation revealed detectable JNK activation at 10(-9) mol/L and maximal activation at 10(-6) mol/L. Ang II activated JNK through the AT1 receptor, and the activation was attenuated by the downregulation of protein kinase C or the chelation of intracellular Ca2+. Although the addition of either Ca2+ ionophore or phorbol ester resulted in little or no activation of JNK, simultaneous addition of both Ca2+ ionophore and phorbol ester markedly activated JNK. Slight expressions of the c-jun gene were observed in unstimulated cardiac myocytes, and Ang II increased expressions of the c-jun gene as well as the c-fos gene. Ang II increased transcription of the endothelin-1 gene through the AP-1 binding site. In conclusion, Ang II may activate JNK in cultured cardiac myocytes through an increase in intracellular Ca2+ and activation of protein kinase C, and the activated JNK may regulate gene expression by activating AP-1 during Ang II-induced cardiac hypertrophy.

Protein kinase C, but not tyrosine kinases or Ras, plays a critical role in angiotensin II-induced activation of Raf-1 kinase and extracellular signal-regulated protein kinases in cardiac myocytes

Angiotensin II (AngII) induces cardiac hypertrophy through activating a variety of protein kinases. In this study, to understand how cardiac hypertrophy develops, we examined AngII-evoked signal transduction pathways leading to the activation of extracellular signal-regulated protein kinases (ERKs), which are reportedly critical for the development of cardiac hypertrophy, in cultured cardiac myocytes isolated from neonatal rats. Inhibition of protein kinase C (PKC) with calphostin C or down-regulation of PKC by pretreatment with a phorbol ester for 24 h abolished AngII-induced activation of Raf-1 and ERKs, and addition of a phorbol ester conversely induced a marked increase in the activities of Raf-1 and ERKs. Pretreatment with two chemically and mechanistically dissimilar tyrosine kinase inhibitors, genistein and tyrphostin, did not attenuate AngII-induced activation of ERKs. In contrast, genistein strongly blocked insulin-induced ERK activation in cardiac myocytes. Although pretreatment with manumycin, a Ras farnesyltransferase inhibitor, or overexpression of a dominant-negative mutant of Ras inhibited insulin-induced ERK activation, neither affected AngII-induced activation of ERKs. Overexpression of a dominant-negative mutant of Raf-1 completely suppressed ERK2 activation by AngII, endothelin-1, and insulin. These results suggest that PKC and Raf-1, but not tyrosine kinases or Ras, are critical for AngII-induced activation of ERKs in cardiac myocytes.

Lyophilized preliposomal formulation of the non-cross-resistant anthracycline annamycin: effect of surfactant on liposome formation, stability and size

We report a method of preparing a submicron and stable liposome formulation of the non-cross-resistant anthracycline annamycin. The lipids were dimyristoylphosphatidyl choline (DMPC) and dimyristoylphosphatidyl glycerol (DMPG) at a 7:3 molar ratio and the optimal lipid:drug ratio was 50:1 (w/w). The selected formulation was a preliposome lyophilized powder that contained the phospholipids, annamycin, and Tween 20. The liposome suspension was obtained on the day of use by adding normal saline at 37 degrees C (1 ml/mg annamycin) and hand shaking for 1 min. The presence of Tween 20 was essential in shortening the reconstitution step (from > 2 h to 1 min), avoiding the early formation of free drug crystals, and reducing the median particle size by tenfold (from 1.5 microm to 0.15 microm) without destroying the liposome vesicles. At room temperature, the preliposome powder was chemically stable for > 3 months, and the liposome suspension was chemically and physically stable for > 24 h. The in vitro cytotoxicity of the formulation was equivalent to that of the same lipid composition prepared by the standard evaporation method. The results of the study indicate that small amounts of surfactant may be used to enhance the reconstitution step and reduce the size of liposome suspensions obtained from lyophilized preliposome powders. The formulation described is being used for ongoing clinical trials with liposomal annamycin.

Artificial neural network to assist psychiatric diagnosis

BACKGROUND

Artificial Neural Network (ANN), as a potential powerful classifier, was explored to assist psychiatric diagnosis of the Composite International Diagnostic Interview (CIDI).

METHOD

Both Back-Propagation (BP) and Kohonen networks were developed to fit psychiatric diagnosis and programmed (using 60 cases) to classify neurosis, schizophrenia and normal people. The programmed networks were cross-tested using another 222 cases. All subjects were randomly selected from two mental hospitals in Beijing.

RESULTS

Compared to ICD-10 diagnosis by psychiatrists, the overall kappa of BP network was 0.94 and that of Kohonen was 0.88 (both P < 0.01). In classifying patients who were difficult to diagnose, the kappa of BP was 0.69 (P < 0.01). ANN-assisted CIDI was compared with expert system assisted CIDI (kappa = 0.72-0.76); ANN was more powerful than a traditional expert system.

CONCLUSION

ANN might be used to improve psychiatric diagnosis.

[Preparation of galactosyl-cytochrome C and studies on its hepatic targeting property]

This paper reports the preparation of the coupling compound between thiogalactose and cytochrome C(Cyt-C). The binding tests of this compound to asialoglycoprotein receptor have also been carried out in vivo. The results show that the pharmacokinetics of this compound is in accordance with the basic characteristic of receptor induced binding. The highest uptake of liver reaches to 32.9% and at the same time the conjugate remains 78.6% the biological activity of Cyt-C. It is possibly a hepatic targeting drug or a hepatic targeting carrier.

Mechanical stretch activates the stress-activated protein kinases in cardiac myocytes

We have recently shown that mechanical stress activates a phosphorylation cascade of protein kinases including Raf-1 and the extracellular signal-regulated kinases (ERKs) in cultured cardiac myocytes partially through the enhanced secretion of angiotensin II. Osmotic stress in budding yeast has been shown to activate similar signaling molecules including Hog-1, a distant relative of the ERK family. In the present study, we examined whether mechanical stretch of cardiac myocytes activates the stress-activated protein kinases (SAPKs)/c-Jun NH2-terminal kinase, the mammalian homologs of yeast Hog-1 that regulate gene expression through activation of the transcription factor, AP-1. When cardiac myocytes of neonatal rats cultured on a deformable silicone dish were stretched, activity of SAPKs was increased from 10 min, peaked at 30 min, and gradually decreased thereafter. The increase in activity of SAPKs was proportional to the stretch. Unlike ERKs, the activation of SAPKs by stretching cardiac myocytes was not dependent on the secreted angiotensin II. The chelation of extracellular Ca2+ or down-regulation of protein kinase C did not attenuate activation of SAPKs by stretch. Transfection experiments using an AP-1 binding site-containing reporter gene revealed that stretch increases AP-1 activity in cardiac myocytes. In conclusion, like osmotic stress in yeast, mechanical stretch activates SAPKs in cardiac myocytes without the participation of angiotensin II. These results suggest that the activation of SAPKs may regulate gene expression during mechanical stress-induced cardiac hypertrophy.

Lipid-complexed camptothecin: formulation and initial biodistribution and antitumor activity studies

Water-soluble derivatives of camptothecin, and active topoisomerase I inhibitor, have shown a broad spectrum of activity against human tumors. Early clinical trials with the water-soluble sodium salt of camptothecin were hindered by significant cystitis, gastroenteritis, and leukopenia. Furthermore, the sodium salt of camptothecin has been shown to have significantly less activity than the water-insoluble lactone form of the compound. We describe a formulation of lipid-complexed CPT (LC-CPT; particle size range 20.8-208.1 nm) that is very easy to prepare and allows for intravenous administration in vivo in clinically relevant lipid-drug ratios (12.5:1 w/w). The lipid formulation had in vitro antitumor activity similar to that of CPT formulated without lipids and displayed similar cytotoxicity against MDR-1-negative and -positive tumor cells. The biodistribution of CPT was profoundly affected by lipid complexation; free CPT achieved the greatest concentration in the pulmonary parenchyma while LC-CPT achieved the highest concentration in the gastrointestinal tract. LC-CPT had significant antitumor activity in vivo against intraperitoneal L1210 and P338 leukemia and appeared to be more potent then free CPT.

[Determination of metronidazole in serum by HPLC]

This paper report a sensitive and rapid method for the determination of metronidazole (MTZ) using theophylline as the internal standard. High performance liquid chromatograph model 344 (Beckman) with a 254 nm wavelength UV detector and YWG-C18H37 column (10 microns, 250 x 4.6 mm) was used. To the serum sample 200 microliters, 100 microliters phosphate buffer (0.8 mol/L, pH 7.5) was added, then extracted with 3 ml chloroform containing 5% isopropyl alcohol. The organic layer was removed and evaporated to dryness under an air stream in a 40 degrees C water bath. The residue was dissolved in 30 microliters mobile phase and 20 microliters injected. The mobile phase of water-methanol (73:27) was pumped at 1.0 ml/min through the column. The detector operated at 0.005 aufs. The retention times for MTZ and theophylline were 5.78 and 6.81 min respectively. Standard curve was linear in the concentration range of 0.3125 to 20 mg/L. The detection limit in serum was 0.02 mg/L. Extraction recovery was 77%-82%; method recovery 99%-102%; withinday RSD less than 3.0%; inter-day RSD less than 3.5%.

Endothelin-1 is involved in mechanical stress-induced cardiomyocyte hypertrophy

We have recently shown that mechanical stress induces cardiomyocyte hypertrophy partly through the enhanced secretion of angiotensin II (ATII). Endothelin-1 (ET-1) has been reported to be a potent growth factor for a variety of cells, including cardiomyocytes. In this study, we examined the role of ET-1 in mechanical stress-induced cardiac hypertrophy by using cultured cardiomyocytes of neonatal rats. ET-1 (10(-8) approximately 10(-7) M) maximally induced the activation of both Raf-1 kinase and mitogen-activated protein (MAP) kinases at 4 and 8 min, respectively, followed by an increase in protein synthesis at 24 h. All of these hypertrophic responses were completely blocked by pretreatment with BQ123, an antagonist selective for the ET-1 type A receptor subtype, but not by BQ788, an ET-1 type B receptor-specific antagonist. BQ123 also suppressed stretch-induced activation of MAP kinases and an increase in phenylalanine uptake by approximately 60 and 50%, respectively, but BQ788 did not. ET-1 was constitutively secreted from cultured cardiomyocytes, and a significant increase in ET-1 concentration was observed in the culture medium of cardiomyocytes after stretching for 10 min. After 24 h, an approximately 3-fold increase in ET-1 concentration was observed in the conditioned medium of stretched cardiomyocytes compared with that of unstretched cardiomyocytes. ET-1 mRNA levels were also increased at 30 min after stretching. Moreover, ET-1 and ATII synergistically activated Raf-1 kinase and MAP kinases in cultured cardiomyocytes. In conclusion, mechanical stretching stimulates secretion and production of ET-1 in cultured cardiomyocytes, and vasoconstrictive peptides such as ATII and ET-1 may play an important role in mechanical stress-induced cardiac hypertrophy.

Activation of p70 S6 protein kinase is necessary for angiotensin II-induced hypertrophy in neonatal rat cardiac myocytes

Although many lines of evidence have suggested that angiotensin II (Ang II) plays an important role in development of cardiac hypertrophy, the mechanism by which Ang II increases protein synthesis in cardiac myocytes remains unclear. It has been reported that the phosphorylation of S6 protein in 40 S ribosome is correlated to the efficiency of protein synthesis. In the present study, we have examined whether Ang II activates p70 S6 kinase (p70S6K), which has been reported to phosphorylate S6 protein. Ang II activated p70S6K through AT1 receptor. An immunosuppressant agent, rapamycin, inhibited Ang II-induced p70S6K activation but not the activation of MAP kinases or the induction of c-fos gene expression. Rapamycin also abolished Ang II-induced increase in protein synthesis. These results suggest that Ang II induces cardiac hypertrophy by activating p70S6K.

[Control of growth and expression of protooncogenes in regenerating liver]

There are many humoral factors involved in the control of growth in regenerating liver. The complete hepatocyte mitogens such as hepatocyte growth factor (HGF), hepatic stimulator substance (HSS) can strongly stimulate hepatocyte DNA synthesis and mitosis. The hepatocyte growth inhibitors such as transforming growth factor beta 1 (TGF beta 1), however, do not stimulate DNA synthesis, but inhibit EGF mitogenesis. In addition, the comitogens such as norepinephrine and insulin are necessary to regulate the growth of regenerating liver. It has become clear that the hepatocyte proliferation and protooncogenes are linked closely. Some protooncogenes can express specifically as markers in the different phases of the cell cycle and in hepatocytes that enter the cell cycle (G0 to G1 transit) and continue to progress.

Effects of geometric isomerism and ligand substitution in bifunctional dinuclear platinum complexes on binding properties and conformational changes in DNA

The DNA binding profile of a series of dinuclear platinum complexes [{trans-PtCl-(L)2}2H2N(CH2)nNH2]2+ (L = NH3 or py; 1,1/t,t/NH3 and 1,1/t,t/py, respectively) and [{cis-PtCl-(NH3)2H2N(CH2)nNH2]2+ (1,1/c,c/NH3) was examined to compare the effects of geometrical isomerism and the presence of ligands other than NH3 in the coordination sphere. Steric effects, because of the geometry of the leaving groups cis to the diamine bridge or the presence of planar pyridine ligands, result in diminished binding to calf thymus DNA for these isomers. In contrast, the pyridine derivative shows a distinct binding preference for poly(dG-dC).poly(dG-dC) in comparison to both NH3 isomers. Both NH3 complexes induced the B-->Z transition in poly(dG-dC).poly(dG-dC), but the presence of a pyridine ligand stabilized the B conformation. The bifunctional binding of the NH3 isomers results in unwinding of supercoiled pUC19 plasmid DNA equivalent to cis-DDP, while the unwinding of the pyridine derivative is approximately twice that of the mononuclear trans-[PtCl2(py)2]. DNA-DNA interstrand cross-linking is very efficient for all three agents, but sequencing studies indicated that only the 1,1/t,t/NH3 derivative is capable of forming a (Pt,Pt) intrastrand cross-link to the adjacent guanines of a d(GpG) sequence. The effects on DNA caused by bifunctional binding of dinuclear complexes are compared with those from the mononuclear [PtCl2(NH3)2] isomers. The results are discussed with respect to the antitumor activity of the dinuclear series.

Preclinical toxicity of liposome-incorporated annamycin: selective bone marrow toxicity with lack of cardiotoxicity

Annamycin (Ann) is a new lipophilic anthracycline antibiotic with a marked ability to circumvent typical multidrug resistance both in vitro and in vivo. Because of its high affinity for lipid membranes and very low solubility in water, Ann has been prepared in a submicron liposome formulation (L-Ann) that is currently being investigated in a Phase I clinical study. We studied the preclinical toxicity of L-Ann in mice and beagle dogs and compared it with that of free Ann in suspension and the parent compound doxorubicin (Dox). In mice, free Ann was about twice as toxic as Dox (LD50 after a single i.v. bolus administration, 8.8 versus 19.9 mg/kg; P < 0.01). The liposomal carrier reduced Ann toxicity by 2-fold (LD50, 15.74 mg/kg for L-Ann versus 8.8 mg/kg for free Ann; P < 0.01). Granulocytopenia was the main toxicity of Ann, either free or liposome incorporated, and was much more profound than with an equitoxic dose of Dox as assessed by blood counts and pathological studies. In chronic mouse studies, L-Ann was remarkably less cardiotoxic than Dox. Cumulative toxicity with the weekly administration of a given fraction of the subacute LD10 was markedly higher with Dox than with L-Ann as assessed by body weight and mortality studies. L-Ann also had less vesicant toxicity than Dox after intradermal administration in mice. Beagle dogs tolerated the mouse-equivalent LD10 dose of L-Ann (1.4 mg/kg) with no side effects, changes in the hematological and biochemical blood parameters, or pathological changes. Our results indicate that: (a) L-Ann is more selectively myelotoxic than Dox and is noncardiotoxic; (b) the liposome carrier plays a major role in the favorable toxicity profile of L-Ann; and (c) the standard one-tenth of the LD10 should be a safe starting dose for Phase I clinical trials with L-Ann in humans.

Interaction of the UvrABC nuclease system with a DNA duplex containing a single stereoisomer of dG-(+)- or dG-(-)-anti-BPDE

Oligonucleotides containing site-specifically-modified N2-guanine (+)-trans-, (-)-trans-, (+)-cis-, and (-)-cis-BPDE adducts were ligated into 50-base-pair DNA fragments. These substrates were used in reactions with the Escherichia coli UvrABC nuclease system. The interaction of the UvrA2 and UvrA2B complexes with these four stereoisomers was probed using DNase I footprinting and gel mobility shift assays. DNase I digestion of substrates containing each stereoisomer of BPDE displayed a unique pattern which was consistent with the known structure of these DNA adducts. UvrA and UvrA2B appeared to interact very similarly with all four substrates. Binding of UvrA2 to these substrates produced a 33-bp footprint, and the UvrB--DNA complex resulted in footprint of 24 bp. The UvrABC nuclease system produced bimodal incisions at the eighth phosphate 5' and the fifth, sixth, or seventh phosphate 3' to the modified guanine. The variation of the 3' incision site was linked to the stereochemistry and orientation of the BPDE adduct. For example, the 3' incision of the 50-bp duplex containing (-)-trans-BPDE-N2-guanine was inhibited at the fifth phosphate. UvrABC nuclease incision kinetics revealed a hierarchy of specificity. The intercalative cis isomers were incised more efficiently than the corresponding trans isomers which lie in the minor groove. The (+) enantiomers were incised more efficiently than the (-) form for both cis and trans isomers. These observations reveal that UvrABC nuclease recognition and incision are directly influenced by the conformation of the DNA adduct.

Nd: YAG laser lysis of the fibrinous membrane and remnant substance on the anterior surface of intraocular lens

PURPOSE

To determine the effects of Nd: YAG laser to disrupt the fibrinous membrane and remnant substance on the anterior surface of intraocular lens.

METHODS

Nd: YAG laser was applied on 23 cases of fibrinous membrane formation and 8 cases of remnant substance on the anterior surface of intraocular lenses (IOL) which had not responded well to steroid therapy. Eighteen cases were male and 13 female. The mean age was 49.7 years (range, 5 approximately 78 years). The interval between IOL implantation and laser therapy was 0.5 approximately 30 months in the fibrinous membrane cases and 3 approximately 10 days in the remnant substance cases. The energy applied was 0.8 approximately 3.0 mJ/exp. with 2 approximately 112 exposures. Mean follow-up period was 3.6 months.

RESULTS

Complications during therapy included only 2 cases of slight iris bleeding. Visual acuity after therapy was improved 1 line in 16 cases, 2 lines in 11 cases, 3 lines in 1 case, 4 lines in 1 case and 5 lines in 2 cases. No post-therapy complication was found.

CONCLUSIONS

Nd: YAG laser lysis is an effective alternative to remove the fibrinous membrane and remnant substances on the anterior surface of IOL.