Transgenic potato plants expressing osmotin gene inhibits fungal development in inoculated leaves

Osmotin, a 24-KD protein isolated from Nicotiana tabacum 'Xanthi nc' was very toxic to Phytophthora infestans in vitro assay. Transgenic potato plants expressing wild osmotin protein delayed the emergence of symptoms of disease. Two osmotin mutants have been produced by PCR mutagenesis. One mutant, delta C18 osmotin, had a nonsense mutation near the C-terminus that deleted the carboxyl terminal prepropeptide (CTPP) of 18 amino acids. Another mutant, osmotin-P, had amber mutation at 96th amino acid. Both mutant genes driven by CaMV d35S promoter were introduced in potato by Agrobacterium mediated genetic transformation. The expression and osmotin protein accumulation in transgenic potato were detected by Southern, Northern, and Dot-blot ELISA assay. Disease resistance test using P.infestens complex race showed that expression of both osmotin mutants in transgenic potato reduced the lesion growth rate in inoculated leaves. The results showed that accumulation of osmotin protein in intercellular spaces (delta C18osmotin) inhibited the development of fungal disease in inoculated leaves. Based on the results we suggest that antifungal activity was possibly located at N end of osmotin protein (osmotin-P).

Tumor-specific PAX3-FKHR transcription factor, but not PAX3, activates the platelet-derived growth factor alpha receptor

The t(2;13) chromosomal translocation occurs at a high frequency in alveolar rhabdomyosarcoma, a common pediatric tumor of muscle. This translocation results in the production of a chimeric fusion protein derived from two developmentally regulated transcription factors, PAX3 and FKHR. The two DNA binding modules, the paired domain and the homeodomain, of PAX3 are fused in frame to the transactivation domain of FKHR. Previously, tumor-specific PAX3-FKHR has been shown to bind to DNA sequences normally recognized by wild-type PAX3 and to exhibit relatively enhanced transcriptional activity. The DNA binding sites used to demonstrate that PAX3-FKHR is a more potent transcriptional activator than PAX3 have included recognition sequences for the paired domain of PAX3. In this report, we demonstrate the ability of PAX3-FKHR to activate the product of a growth control gene, platelet-derived growth factor alpha receptor (PDGFalphaR), by recognizing a paired-type homeodomain binding site located in the PDGFalphaR promoter. PAX3 alone cannot mediate transcriptional activation of this promoter under the conditions tested. This provides the first evidence that chromosomal translocation results in altered target gene specificity of PAX3-FKHR and suggests a transcriptional target that may play a significant role in oncogenic activity and rhabdomyosarcoma development.

Identification of denitrifier strain T1 as Thauera aromatica and proposal for emendation of the genus Thauera definition

Bacterial strain, T1, originally isolated by P.J. Evans on the basis of its capacity for toluene degradation under denitrifying conditions, has been classified as Thauera aromatica. In a comprehensive study of strains of this species, it was found that the cells have a different type of flagellar insertion from that of cells of the type species of the genus, Thauera selenatis, suggesting the convenience of an emendation of the description of the genus Thauera. Further studies on a larger collection of strains with the above characteristics may serve in the future as the basis for the creation of a new generic designation.

[Otoacoustic emissions and tinnitus]

Methods of objective tinnitus testing exploration causes of tinnitus and the relationship between OAE and tinnitus are reported. In 306 ears with tinnitus (with or without hearing loss), Distortion Products Otoacoustic Emission (DPOAE), Spontaneous OAE (SOAE) and Transiently Evoked OAE (TEOAE) were tested by ILO92 Otodynamics Analyzer. Results indicated that 1. In these cases there was no correlation between the frequency of tinnitus and SOAE. 2. In 94.8% of sensorineural hearing loss with tinnitus the DPOAE-gram presented lower amplitude or was absent within the frequency range of elevated pure-tone-thresthold; In 59% of cases with normal hearing and tinnitus the amplitude of DPOAE at nearby frequencies of tinnitus was decreased and there was no SOAE detectable. At frequencies other than that of tinnitus, the amplitude of DPOAE was normal and SOAE could be recorded. So OAE could reflect cochlear lesion in early stage.

Functional analysis of the CAAT box in the major late promoter of the subgroup C human adenoviruses

Comparisons among sequences predicted to encode the major late promoter (MLP) of adenoviruses from a wide variety of host species show that an inverted CAAT box is among the most highly conserved transcription elements found in the putative MLPs. The high degree of conservation suggests that the CAAT box plays an important role in the function of the MLP in vivo, an idea supported by a previous mutational analysis of the core CCAAT sequence. To address the importance of the CAAT box, in terms both of quantitative levels of transcription and of specificity, a further set of mutations was created and examined in the context of the viral genome. One mutation, CAAT5, contains individual changes at five positions, four of which correspond to invariant residues in a CAAT box consensus derived either by computer analysis or empirically. The CAAT5 mutation had no discernible phenotype by itself but when coupled with the previously described USF0 mutation, which disrupts binding of the upstream stimulating factor (USF) but is otherwise phenotypically silent, gave rise to virus with a severe replication deficiency. Nuclear run-on assays showed that transcription initiation at the mutant MLP was significantly reduced compared with that of the wild type or the virus containing CAAT5 alone. Replication of the double mutant was lower than that of the previously described USF0::CCCAT virus, suggesting that the additional mutations in the CAAT box had further lowered the binding of transcription factor CP1 (also called CBF, NF-Y). Replacement of the CAAT box by an ATF binding site or an OCT1 binding site had no phenotypic effect in an otherwise wild-type background, but replacement in a USF0::CCCAT background led to only partial restoration of the wild-type phenotype. The failure to restore the functional redundancy normally exhibited by the CAAT box and the proximal upstream activating element is consistent with the idea that in the adenovirus MLP the CAAT box is preferred over others as the distal transcriptional element.

A Generalized Drop Length-Height Method for Determination of Contact Angle in Drop-on-Fiber Systems

A generalized drop length-height method is introduced here for the determination of contact angle in the drop-on-fiber systems. This method overcomes some of the difficulties encountered in the practice by applying the common maximum drop length-height method to determine the contact angle. Furthermore, with this new generalized method a large part of a drop profile can be used in the calculation, which reduces the statistical error of the determination and improves the reliability and accuracy of the obtained results. The method has been examined using both the theoretically simulated and the experimentally obtained drop profiles. The accuracy of the method has been estimated to be in order of 0.5-1degrees for the drop profiles of usual experimental quality, which can be obtained using common digital image processing hardware and software. Copyright 1998 Academic Press. Copyright 1998Academic Press

Detection of genomic instability in lung cancer tissues by random amplified polymorphic DNA analysis

Genomic instability resulting in multiple mutations is believed to be a driving force in the carcinogenic process. In this study, the random amplified polymorphic DNA (RAPD) technique, a simple PCR-based DNA polymorphism assay system, was used for detecting genomic instability in lung cancer tissues. DNAs from 20 lung cancer (18 non-small cell lung cancers and two small cell lung cancers) and their corresponding normal tissues were amplified individually by RAPD with seven different 10-base arbitrary primers. PCR products from RAPD were electrophoretically separated in agarose gels and banding profiles were visualized by ethidium bromide staining. The ability to detect genomic instability in 20 cancer tissues by each single primer ranged from 15 to 75%. DNA changes were detected by at least one primer in 19 (95%) cancer tissues. These results seem to indicate that genomic rearrangement is associated with lung carcinogenesis and that RAPD analysis is useful for the detection of genomic instability in lung cancer tissues.

Functional characterization of the major late promoter of mouse adenovirus type 1

During the late phase of adenovirus infection, the major late promoter (MLP) controls the regulated expression of the genes that encode most viral structural proteins. Recently, the region of the genome of mouse adenovirus type 1 (MAV-1), predicted to contain the MLP, was sequenced and compared to that of the human virus MLP. The general organization of the transcriptional elements of the putative MAV-1 MLP is similar to that of the human virus counterpart, with some interesting differences. We wished to investigate the function of the predicted MLP of MAV-1 and to determine the significance of the differences found in the MAV-1 MLP. To test the activity of the predicted MLP of MAV-1, both Northern blot and primer extension analyses were performed on intracellular RNA isolated from cells infected with MAV-1. The results show that late RNA can be detected 48 hr postinfection and increases up to 6 days p.i. Primer extension analysis revealed that the major start sites of transcription are 28 and 31 nt downstream of the first T residue of the predicted TATA box. To analyze the functional significance of the predicted transcriptional elements, a transient transfection system, using the firefly luciferase gene controlled by the MAV-1 MLP sequence, was established. The predicted MLP sequence was capable of directing luciferase gene expression, to a level some 60% of that of the human virus MLP. Mutations were created in the inverted CAAT box, the SP1 site, and the TATA box, either singly or in combination. Each single-element mutation causes a marked reduction in luciferase gene expression, with the SP1 mutation showing the greatest effect. Double mutations were even more deficient, suggesting a level of functional redundancy among the various transcriptional elements. Finally, the putative SP1-binding site was examined by gel mobility shift assay and shown to interact with purified SP1 protein specifically, supporting the functional significance of this transcriptional element. These findings contribute to a better understanding of gene expression in MAV-1 and to its development as an appropriate model for the study of the molecular basis of pathogenesis in a natural host animal.

Distribution of p53 and K-ras mutations in human lung cancer tissues

Studies were performed to examine the mutational pattern of K-ras exons 1 and 2 and p53 exons 5-8 in lung cancer tissues from 27 Chinese patients (10 smokers, 17 non-smokers) using single-stranded conformational polymorphism and DNA sequencing. K-ras mutations were found in 13/27 tumors (48%); all mutations were clustered in exon 1 and distributed between codons 9 and 32. The frequency and number of patients with K-ras mutations between smokers and non-smokers were not different, except that a high frequency of G --> A transitions (11/11) was found in non-smokers. Among cell types, K-ras mutations were found in 7/13 (54%) squamous cell carcinoma (SC) and 5/12 (42%) adenocarcinoma (AC) patients. A --> T transversions (all six transversions) were present only in SC. In p53, 18/27 (67%) tumors contained mutations in exons 7 and 8, frequently at codons 226, 270, 275 and 281. The number of tumors with p53 mutations in smokers (70%) and in non-smokers (65%) was similar, and the mutation frequency did not differ except for a higher number of G --> A (6/7) and T --> C (5/6) transitions in non-smokers. Among cell types, the number of tumors with p53 mutations was 9/13 (69%) in SC and 8/12 (67%) in AC. The A --> G (11/16) transitions and A --> C (4/4) transversions in p53 were more frequent in SC than in AC (P < 0.04 for A --> G; P < 0.02 for A --> C). The varying mutation patterns in both the K-ras and p53 genes between smokers and non-smokers and among cell types suggest that other than cigarette smoke, environmental and dietary factors may also be involved in the genesis of lung cancer among these patients.

Studies of renal injury. II. Activation of the glucose transporter 1 (GLUT1) gene and glycolysis in LLC-PK1 cells under Ca2+ stress

Injury to the renal proximal tubule is common and may be followed by either recovery or cell death. The survival of injured cells is supported by a transient change in cellular metabolism that maintains life even when oxygen tension is reduced. This adaptive process involves the activation of the gene encoding the glucose transporter GLUT1, which is essential to maintain the high rates of glucose influx demanded by glycolysis. We hypothesized that after cell injury increases of cell Ca2+ (Ca2+i) initiate the flow of information that culminates with the upregulation of the stress response gene GLUT1. We found that elevations of Ca2+i caused by the calcium ionophore A23187 activated the expression of the GLUT1 gene in LLC-PK1 cells. The stimulatory effect of Ca2+i on GLUT1 gene expression was, at least in part, transcriptional and resulted in higher levels of GLUT1 mRNA, cognate protein, cellular hexose transport activity, glucose consumption, and lactate production. This response was vital to the renal cells, as its interruption severely increased Ca2+-induced cytotoxicity and cell mortality. We propose that increases of Ca2+i initiate stress responses, represented in part by activation of the GLUT1 gene, and that disruption to the flow of information originating from Ca2+-induced stress, or to the coordinated expression of the stress response, prevents cell recovery after injury and may be an important cause of permanent renal cell injury and cell death.

Conservation of DNA sequence in the predicted major late promoter regions of selected mastadenoviruses

The major late promoter (MLP) of the subgroup C human adenoviruses is a preeminent model for the study of the mechanisms of basal and activated transcription, both in vivo and in vitro. However, while the structure and function of the human virus MLP has been the subject of extensive investigation, the conservation of the various promoter elements among the adenoviruses from different species has not been examined. Conservation of specific elements would strongly suggest the importance and universality of their function. To address this issue, sequences were obtained from cloned DNAs of several representative Mastadenoviridae, mouse adenovirus type 1 (MAV-1), Tupaia adenovirus type 1 (TAV-1), and two bovine adenoviruses of two distinct subgroups, BAV-3 and BAV-7. The results of the sequencing studies showed that the TATA box and an upstream inverted CAAT box are conserved in all species and that the binding site for transcription factor USF is present in all except MAV-1, in which a sequence similar to an Sp1-binding site is present at a similar position. The initiator element (INR) sequence is not well conserved, and only one or other of the two downstream activating elements, DE1 and DE2, is predicted to be present in the nonprimate virus MLP regions. Ribonuclease protection assays on RNA isolated from MAV-1-infected cells late in infection indicated that the predicted MLP is functional, and transcription initiation and splice donor sites were identified. The human virus MLP is embedded in the essential DNA polymerase sequence on the opposite DNA strand. The primary amino acid sequences of the C-terminal regions of the predicted DNA polymerases show strong conservation of sequence motifs observed in replicative polymerases ranging from prokaryotes to mammals, and additional regions of strong conservation among the adenovirus polymerases. Pairwise comparisons between the newly sequenced regions of the polymerases and previously published sequences show that BAV-7 is most dissimilar to all others, while TAV-1 has a greater similarity to the primate sequences than to the others. The sequence data from both strands were also used to construct phylogenetic trees, based on BAV-7 as the outgroup. The trees constructed from the two sets of sequences are broadly similar, showing close relationships between primate viruses, but differing in the order of divergence of TAV-1 and MAV-1 branches.

[Surgical treatment for congenital motive defect nystagmus by the parks (5, 6, 7, 8mm) procedure or the augmented Parks procedure]

PURPOSE

The purpose of the surgical treatment for patients with congenital motive detect nystagmus was to correct deviation of the eye and the head tilt, to improve vision and eliminate nystagmus.

METHODS

19 patients underwent the Parks (5, 6, 7, 8mm) or the augmented Parks procedure from 1987 to 1994. For patients with abnormal head turn > or = 30 degrees, We used a 40-60% augmented Parks procedure.

RESULTS

A follow up of 19 patients ofr an average of 22 months revealed a marked improvemtnts. After operation, the head turn was decreased form 30.5 degrees to 4.9 degrees, the intensity of nystagmus was decreased from 36.0 to 9.7, 21 eyes (55.3%) of 19 patients improved by two or more lines of Snellen visual acuity.

CONCLUSIONS

The Parks (5, 6, 7, 8mm) and the augmented Parks (5, 6, 7, 8mm) procedure produce a marked correction for congenital motive defect nystagmus.

Cell-type-specific expression of the platelet-derived growth factor alpha receptor: a role for GATA-binding protein

Platelet-derived growth factor alpha receptor (PDGF alpha R) is a transmembrane tyrosine kinase receptor for all three existing PDGF isoforms, AA, AB, and BB. Transcripts of PDGF alpha R are detected as early as in fertilized mouse eggs and throughout adulthood in a time- and space-specific manner, thereby suggesting an important role of PDGFs in mammalian development. In this study, we have investigated the mechanism involved in cell-type-specific PDGF alpha R gene expression during early embryonic development. Using F9 embryonic carcinoma cells as an in vitro study model, we identified a differentiation-dependent enhancer element within the PDGF alpha R promoter that controlled receptor expression during parietal endoderm cell differentiation induced by retinoic acid and dibutyryl cyclic AMP treatment. The differentiation-dependent enhancer element sequence bore no resemblance to consensus DNA-binding sites of either the retinoic acid receptor family or the cyclic AMP-responsive element-binding protein family. It was composed of two identical 12-bp direct repeats separated by a 17-bp insert sequence enriched in C and A nucleotides. Although only a single repeat was needed to form specific DNA-protein complexes with factors present in F9 parietal endoderm cell extracts, both repeats together were necessary to display cell-type-specific enhancing activity. Mutational analysis revealed that the protein-binding sites within the repeat sequences were identical to GATA-binding sites. In this study, we provided evidence to suggest that a member of the GATA transcription factor family (GATA-4) is responsible for parietal endoderm-specific PDGF alpha R expression.

Salivary EGF regulates eosinophil-derived TGF-alpha expression in hamster oral wounds

Using hamster as an oral wound healing model, we examined eosinophils and their expression of transforming growth factor-alpha (TGF-alpha) and transforming growth factor-beta 1 (TGF-beta 1). Oral wounds healed approximately two times faster than their cutaneous counterparts. Eosinophils infiltrated prominently into oral wounds; however, unlike the dual expression of TGF-alpha and TGF-beta 1 in skin wounds, oral wound-associated eosinophils expressed TGF-beta 1, but not TGF-alpha. Because saliva is present in oral environments and contains epidermal growth factor (EGF) and TGF-alpha, sialoadenectomy was performed in this model to determine whether the lack of TGF-alpha expression by eosinophils in oral wounds is due to the presence of salivary EGF and/or TGF-alpha. We found that eosinophils in sialoadenectomized hamsters did express TGF-alpha during oral wound healing but that such expression was suppressed when EGF was added to their drinking water. Taken together, our findings suggest that eosinophil-derived TGF-alpha and salivary TGF-alpha/ EGF may have complementary roles in contributing to TGF-alpha in oral wound healing.

Diet is a risk factor in cisplatin ototoxicity

This study demonstrates that cisplatin ototoxicity depends on dietary factors and correlates with decreased levels of cochlear glutathione and serum albumin. After 12 days of injections, cisplatin (1 mg/kg body weight, s.c.) caused a small hearing loss in guinea pigs fed a regular, full-protein diet (9 +/- 6 dB at 8 kHz and 10 +/- 9 dB at 18 kHz) but a significantly higher hearing loss in animals on a low-protein diet (23 +/- 17 dB at 8 kHz and 32 +/- 23 dB at 18 kHz). Animals on the low-protein diet gained significantly less weight than those on the regular diet, and cisplatin treatment lowered the weight gain in both groups. The low-protein diet also significantly reduced cochlear glutathione levels from 180 +/- 50 to 90 +/- 21 nmol/mg protein and serum albumin from 2.32 +/- 0.04 to 1.75 +/- 0.06 g/dl. Cisplatin treatment tended to decrease glutathione and serum albumin in animals on a full-protein diet but not on the low-protein diet. Renal function was assessed by measuring blood urea nitrogen (BUN) and serum creatinine. While BUN and creatinine values indicated some cisplatin-induced nephrotoxicity, there was no correlation with the severity of ototoxicity. Furthermore, serum platinum levels did not differ between animals on either diet, ruling out a potential influence of altered pharmacokinetics on ototoxicity. These results suggest that the metabolic state of the animal is a risk factor for cisplatin ototoxicity.

Detection of antibodies to rabbit haemorrhagic disease virus: an immunoblotting method using virus-coated human erythrocyte membranes

The virus of rabbit haemorrhagic disease (RHDV) was purified from infected rabbit liver homogenate by using its property to bind to human red blood cells. Lysates from virus coated cells contained a 60 kDa protein identified as the major viral protein. Immunoblots prepared with that preparation were proved to be useful for immunochemical analysis since the 60 kDa component was intensively stained by subsequent incubation with rabbit sera from infected rabbits and with a secondary labelled antibody. The sera from 114 rabbits were analysed with this test and the data were compared with those obtained by using the haemagglutination inhibition test (HIT). Among the 114 field sera tested by Western blot, 86 contained antibodies to the 60 kDa RHDV antigen whereas only 76 showed positive reaction by HIT. The sensitivity and the specificity of the Western blot were 0.85 and 0.45, respectively, with a concordance between the two techniques of 0.72. Additionally, the European brown hare syndrome virus antibodies reacted with the 60 kDa RHDV protein on immunoblots.

[Surgical treatment of colonic and rectal cancer with hepatic metastasis]

In 568 patients with colonic and rectal cancer treated in our hospital from January 1970 to January 1991, 266 had colonic cancer and 302 rectal cancer. 469 patients (263 rectal and 233 colonic) were operated on. A total of 382 patients (186 and 196 colonic) were resectable. The average resection rate was 76.6%. 68 patients (30 rectal and 38 colonic) had hepatic metastasis with a rate of 11.97%. 13 patients (19.1%) had hepatic metastasis focus resected.

Sequence of the mouse adenovirus serotype-1 DNA encoding the precursor to capsid protein VI

The nucleotide sequence predicted to encode the precursor to virion structural protein VI (preVI) of mouse adenovirus (Ad) serotype-1 (MAV-1) was determined. The 237-amino-acid sequence has 45% identity and 66% similarity to the human Ad serotype-2 preVI sequence. There is a marked conservation at the C terminus, the last eleven residues of which may be necessary for activating the Ad endoproteinase, and at the N terminus, including the consensus endoproteinase cleavage site.

Gene expression of epithelial glucose transporters: the role of diabetes mellitus

The functions of absorption of dietary glucose by the small intestine and reabsorption of filtered glucose by the renal proximal tubule are strikingly similar in their organization and in the way they adapt to uncontrolled diabetes mellitus. In both cases, transepithelial glucose and Na+ fluxes are augmented. The epithelial adaptations to hyperglycemia of uncontrolled diabetes are accomplished by increasing the glucose transport surface area and the number of the efflux glucose transporter GLUT2 located in the basolateral membrane. The signals that modify the size of the epithelium and the overexpression of basolateral GLUT2 are not known. It was speculated that high glucose levels and enhanced Na+ flux may be important factors in the signaling event that culminates in a renal and intestinal epithelium that is modified to transport higher rates of glucose against a higher extracellular level of glucose.

Cyclic AMP-dependent protein kinase regulates basal and cyclic AMP-stimulated but not phorbol ester-stimulated transcription of the tyrosine hydroxylase gene

To define the precise role of cyclic AMP (cAMP)-dependent protein kinase (PKA) in transcriptional regulation of the tyrosine hydroxylase (TH) gene, we performed transient cotransfection analyses of a reporter construct containing the upstream 2,400 bp sequence of the rat TH gene with expression plasmids encoding a heat-stable specific inhibitor of PKA (PKI), a mutant regulatory subunit of PKA, or the catalytic subunit of PKA. Inhibition of PKA activity by expression of either PKI or mutant regulatory subunit blocked cAMP-stimulated induction and reduced basal transcription of the TH-reporter construct. Expression of the catalytic subunit of PKA induced the expression of the TH-reporter construct up to 50-fold in a dose-dependent manner. Primer extension analysis confirmed that PKA-mediated induction of TH-reporter expression occurred at the correct transcription initiation site. Expression of PKI did not affect induction following phorbol ester treatment, suggesting that PKA and protein kinase C (PKC) induce TH transcription by independent mechanisms. Finally, a double mutation within the cAMP response element (CRE) of TH2400-CAT diminished its basal and forskolin-stimulated transcription to the level of the promoterless plasmid, pBLCAT3, but did not alter the induction following treatment with phorbol ester, indicating that the CRE is not required for PKC-mediated transcriptional induction. Our results indicate that PKA, via the CRE, plays a crucial role for basal and cAMP-inducible transcription of the TH gene.

Intravitreal pharmacokinetics of liposome-encapsulated amikacin in a rabbit model

BACKGROUND

Intravitreal injection of antibiotics has become a standard therapy for bacterial endophthalmitis. The duration of effective antimicrobial levels in the vitreous after single injection, however, may not be long enough to get optimal response. The authors prepared liposome-encapsulated amikacin for prolonging the duration of intravitreal therapeutic concentrations and investigated the intravitreal pharmacokinetics of the liposomes and amikacin in phosphate buffer solution (PBS) as control.

METHODS

The liposome-encapsulated amikacin was prepared by reverse-phase evaporation method. The intravitreal pharmacokinetics of the liposomes was compared with amikacin in PBS by fluorescence polarization immunoassay. Albino rabbits were randomly distributed into 12 groups. Rabbits in groups 1 to 6 and in groups I to VI (control groups) received an intravitreal injection of the liposome-encapsulated amikacin and amikacin in PBS, respectively.

RESULTS

The encapsulation rate of amikacin was 91%. The time of 50% spontaneous degradation (half-life) of the liposomes in PBS (38 degrees C, pH 7.4) was 47.6 days, and the time of 50% release (half-life) of the drug from the liposomes in PBS was 84.8 hours. The vitreous amikacin concentrations in groups 1 to 6 were significantly greater (P < 0.05) than those in control groups I to VI in every time interval, except in groups 1 to 3 at 1 hour after injection. The difference was particularly obvious in the endophthalmitis groups. The clearance of encapsulated amikacin in vitreous appeared to be related to the state of blood-ocular barrier and to the structural integrity of vitreous. The distribution, the absorption, and the elimination of encapsulated amikacin in vitreous showed the first-order kinetics.

CONCLUSION

The liposome-encapsulated amikacin prolonged half-life of the drug in vitreous. The results of the pharmacokinetic analysis suggested that in endophthalmitis, especially in severe cases, the liposomes may be preferable to conventional preparation.

A dual role for the cAMP-dependent protein kinase in tyrosine hydroxylase gene expression

Tyrosine hydroxylase (TH) catalyzes the conversion of L-tyrosine to 3,4-dihydroxy-L-phenylalanine, the first and rate-limiting step in catecholamine biosynthesis. The cAMP-dependent protein kinase (PKA) phosphorylates and activates the TH enzyme and is thought to mediate transcriptional induction of the TH gene. To better understand the functional role of PKA in TH gene regulation, we studied TH gene expression at the transcriptional, translational, and post-translational levels in several PKA-deficient cell lines derived from rat PC12 pheochromocytoma cells. Strikingly, all PKA-deficient cell lines analyzed in this study showed substantial deficits in basal TH expression as measured by TH enzymatic activity, level of TH immunoreactivity, TH protein level, and steady-state mRNA level. Interestingly, the steady-state level of mRNA correlated well with levels of TH activity, immunoreactivity, and protein. In addition, PKA-deficient cell lines lacked transcriptional induction of the TH gene following treatment with dibutyryl cAMP. Cotransfection of PKA-deficient cells with an expression plasmid for the catalytic subunit of PKA fully reversed transcriptional defect, as indicated by robust transcriptional induction of a reporter construct containing 2400 bp of TH upstream sequence in all PC12 cells tested. These data indicate that the PKA system regulates both the basal and the cAMP-inducible expression of the TH gene primarily at the transcriptional level in PC12 cells.

[A new virus of rabbit. III. Study on morphological superstructure and antigenicity of rabbit hemorrhagic disease virus (RHDV)]

In the spring 1986, an acute infectious disease occurred in Wuhan Second Producing Medical Manufactory, and the rabbit almost died. We tested the mortal symptom and confirmed rabbit Hemorrhagic Disease (RHD) as same as Huang Yinyao report. Hubei Traditional Chinese Medicine Institute appear this RHD also. After we purified virus of above two source by low speed, high speed and sucrose density gradient centrifugation, they can react with antiserum of RHDV from Nanjing Agricultural University in agar gel immunodiffusion tests. These results proved that they belong to the same serotype. Data indicate RHDV have difference morphological superstructure, viral polypeptides and especially RHDV can't react with antiserum of standard Parvovirus of rabbit and so on, so we suggest RHDV is a new virus.

Lambdoid phages as elements of bacterial genomes (integrase/phage21/Escherichia coli K-12/icd gene)

The lambdoid phages are a group of related temperate bacteriophages that lysogenize by site-specific recombination with the bacterial chromosome. Various members of the group have different specific chromosomal insertion sites, despite the fact that the enzymes catalyzing the insertion (integrases) appear to be all descended from a common ancestor. Insertion sites are not located randomly on the E. coli chromosome but are restricted to one segment of the map; also, most prophages are oriented in the same direction along the chromosome. Lambdoid phage 21 inserts within the isocitrate dehydrogenase gene and introduces an alternative 165 bp 3' end for that gene. A defective element (e14) inserts at the same position. We suggest that this mode of insertion arose from insertion of an ancestral phage to the right of icd which then picked up part of the icd gene by abnormal excision and speculate that, at an earlier time, phages may have arrived at their present locations by a process of chromosomal walking.

Mechanistic studies of the phototoxic potential of PD 117596, a quinolone antibacterial compound

PD 117596 is a novel quinolone compound that is being investigated for use as an antibacterial agent. Early investigations demonstrated a significant phototoxic liability associated with this compound. These studies were undertaken to investigate the mechanism of phototoxicity using an in vitro model. In the UVA region, PD 117596 was found to be a more efficient producer of singlet oxygen than rose bengal, ciprofloxacin, nalidixic acid, or PD 118879, another quinolone under investigation. The quantum yield of photoreaction for PD 117596 was relatively low (phi = 0.021); however, it was approximately 10-fold higher than other tested quinolones. In vitro studies using a mouse erythrocyte model were used to further investigate the mechanism of phototoxicity. PD 117596-induced photohemolysis was found to be oxygen dependent with a relatively rapid onset that progressed even after removal of light. Preirradiation of the compound prevented subsequent hemolytic or photohemolytic action. BHA, BHT, alpha-tocopherol, and the iron chelator DTPA were all found to be effective at ameliorating the photohemolytic response. The photohemolytic response was markedly enhanced when D2O was substituted for H2O in the incubation medium, indicating a singlet oxygen-mediated mechanism of action. A rise in thiobarbituric acid products was noted within 1 hr of irradiation and was maximal at the time of onset of overt photohemolysis. These data suggest that singlet oxygen production by irradiated PD 117596 is responsible for secondary changes in mouse red blood cells including lipid peroxidation and ultimately results in cellular lysis.

Immunohistochemical demonstration of epidermal growth factor receptor and ceruloplasmin in thyroid diseases

The expression of epidermal growth factor receptors (EGFR) and ceruloplasmin (CP) in thyroid diseases was investigated by immunohistochemical methods, and the results were compared with the expression of thyroglobulin (TG). Eighty-eight surgical specimens of thyroid diseases, including follicular carcinoma (7 cases), papillary carcinoma (20 cases), follicular adenoma (29 cases), adenomatous goiter (10 cases), diffuse hyperplasia (20 cases) and chronic thyroiditis (2 cases), were studied. All cases of follicular carcinoma and 18 cases (90%) of papillary carcinoma expressed the EGFR immunoreaction in the cytoplasm with a moderate to strong staining intensity. A weak immunoreaction for EGFR was noted in some benign thyroid diseases. CP showed various degrees of positivity in all cases of follicular carcinoma and 19 cases (95%) of papillary carcinoma. The benign thyroid lesions were consistently negative for this antigen, not counting one case of Hürthle cell adenoma. There was a positive correlation between EGFR and CP immunostaining intensity in thyroid carcinomas, representing higher expression of EGFR accompanied by a stronger staining intensity of CP. Except for two cases of papillary carcinoma, all cases showed immunoreaction for TG. The results indicate the enhanced expression of EGFR and CP in thyroid carcinomas. EGFR and CP thus appear to be valuable tools for differential diagnosis between benign and malignant thyroid neoplasms.

Codon preference and primary sequence structure in protein-coding regions

The stochastic complexity of a data base of 365 protein-coding regions is analysed. When the primary sequence is modeled as a spatially homogeneous Markov source, the fit to observed codon preference is very poor. The situation improves substantially when a non-homogeneous model is used. Some implications for the estimation of species phylogeny and substitution rates are discussed.

Spatial organization of axonal microtubules

Several workers have found that axonal microtubules have a uniform polarity orientation. It is the "+" end of the polymer that is distal to the cell body. The experiments reported here investigate whether this high degree of organization can be accounted for on the basis of structures or mechanisms within the axon. Substantial depolymerization of axonal microtubules was observed in isolated, postganglionic sympathetic nerve fibers of the cat subjected to cold treatment; generally less than 10% of the original number of microtubules/micron 2 remained in cross section. The number of cold stable MTs that remained was not correlated with axonal area and they were also found within Schwann cells. Microtubules were allowed to repolymerize and the polarity orientation of the reassembled microtubules was determined. In fibers from four cats, a majority of reassembled microtubules returned with the original polarity orientation. However, in no case was the polarity orientation as uniform as the original organization. The degree to which the original orientation returned in a fiber was correlated with the number of cold-stable microtubules in the fiber. We suggest that stable microtubule fragments serve as nucleating elements for microtubule assembly and play a role in the spatial organization of neuronal microtubules. The extremely rapid reassembly of microtubules that we observed, returning to near control levels within the first 5 min, supports microtubule elongation from a nucleus. However, in three of four fibers examined this initial assembly was followed by an equally rapid, but transient decline in microtubule number to a value that was significantly different than the initial peak. This observation is difficult to interpret; however, a similar transient peak has been reported upon repolymerization of spindle microtubules after pressure induced depolymerization.