Mechanical transmission of dengue virus by Aedes aegypti may influence disease transmission dynamics during outbreaks

BACKGROUND

Dengue virus outbreaks are increasing in number and severity worldwide. Viral transmission is assumed to require a minimum time period of viral replication within the mosquito midgut. It is unknown if alternative transmission periods not requiring replication are possible.

METHODS

We used a mouse model of dengue virus transmission to investigate the potential of mechanical transmission of dengue virus. We investigated minimal viral titres necessary for development of symptoms in bitten mice and used resulting parameters to inform a new model of dengue virus transmission within a susceptible population.

FINDINGS

Naïve mice bitten by mosquitoes immediately after they took partial blood meals from dengue infected mice showed symptoms of dengue virus, followed by mortality. Incorporation of mechanical transmission into mathematical models of dengue virus transmission suggest that this supplemental transmission route could result in larger outbreaks which peak sooner.

INTERPRETATION

The potential of dengue transmission routes independent of midgut viral replication has implications for vector control strategies that target mosquito lifespan and suggest the possibility of similar mechanical transmission routes in other disease-carrying mosquitoes.

FUNDING

This study was funded by grants from the National Health Research Institutes, Taiwan (04D2-MMMOST02), the Human Frontier Science Program (RGP0033/2021), the National Institutes of Health (1R01AI143698-01A1, R01AI151004 and DP2AI152071) and the Ministry of Science and Technology, Taiwan (MOST104-2321-B-400-016).

Honey bee foraging ability suppressed by imidacloprid can be ameliorated by adding adenosine

Honey bees are important pollinators in most ecosystem, but they are currently facing many threats, which have led to a reduction in their population. Previous studies have indicated that neonicotinoid pesticide can impair the memory and learning ability of honey bees, which can eventually lead to a decline in their foraging and homing abilities. In this study, we investigated the homing ability barrier from the perspective of energy supply. We believe that when worker bees experience stress, their energy supply may shift from pro-movement to pro-resistance; this will lead to inadequate energy provision to the flight muscles, causing a reduction in wingbeat frequency and impairing the flight ability of the worker bees. To test this, the worker bees were treated with imidacloprid, and wing beats between the treatment groups were compared. Their glucose, glycogen, trehalose, and ATP contents were also measured, and their genes for energy metabolism and resistance were analyzed. The addition of adenosine improved the ATP content and helped recover the wingbeat frequency of the worker bees. The preliminary results obtained showed that wingbeat frequency and glucose content in the worker bees treated with imidacloprid were significantly lower than those in the control group. This result is consistent with our hypothesis and demonstrates that energy supply imbalances can prevent worker bees from returning to their hives.

CLEC5A mediates Zika virus-induced testicular damage

BACKGROUND

Zika virus (ZIKV) infection is clinically known to induce testicular swelling, termed orchitis, and potentially impact male sterility, but the underlying mechanisms remain unclear. Previous reports suggested that C-type lectins play important roles in mediating virus-induced inflammatory reactions and pathogenesis. We thus investigated whether C-type lectins modulate ZIKV-induced testicular damage.

METHODS

C-type lectin domain family 5 member A (CLEC5A) knockout mice were generated in a STAT1-deficient immunocompromised background (denoted clec5a^-/-stat1^-/-) to enable testing of the role played by CLEC5A after ZIKV infection in a mosquito-to-mouse disease model. Following ZIKV infection, mice were subjected to an array of analyses to evaluate testicular damage, including ZIKV infectivity and neutrophil infiltration estimation via quantitative RT-PCR or histology and immunohistochemistry, inflammatory cytokine and testosterone detection, and spermatozoon counting. Furthermore, DNAX-activating proteins for 12 kDa (DAP12) knockout mice (dap12^-/-stat1^-/-) were generated and used to evaluate ZIKV infectivity, inflammation, and spermatozoa function in order to investigate the potential mechanisms engaged by CLEC5A.

RESULTS

Compared to experiments conducted in ZIKV-infected stat1^-/- mice, infected clec5a^-/-stat1^-/- mice showed reductions in testicular ZIKV titer, local inflammation and apoptosis in testis and epididymis, neutrophil invasion, and sperm count and motility. CLEC5A, a myeloid pattern recognition receptor, therefore appears involved in the pathogenesis of ZIKV-induced orchitis and oligospermia. Furthermore, DAP12 expression was found to be decreased in the testis and epididymis tissues of clec5a^-/-stat1^-/- mice. As for CLEC5A deficient mice, ZIKV-infected DAP12-deficient mice also showed reductions in testicular ZIKV titer and local inflammation, as well as improved spermatozoa function, as compared to controls. CLEC5A-associated DAP12 signaling appears to in part regulate ZIKV-induced testicular damage.

CONCLUSIONS

Our analyses reveal a critical role for CLEC5A in ZIKV-induced proinflammatory responses, as CLEC5A enables leukocytes to infiltrate past the blood-testis barrier and induce testicular and epididymal tissue damage. CLEC5A is thus a potential therapeutic target for the prevention of injuries to male reproductive organs in ZIKV patients.

Demographic Characteristics and Population Simulation of Newly Invasive Fall Armyworm on Arachis hypogaea (Fabales: Fabaceae) and Dominant Green Manure Plant in Taiwan

Spodoptera frugiperda (J.E. Smith) is a severe and fast-spreading pest of numerous agro-economic crops, including miscellaneous, vegetables, and green manure crops. Understanding pest ecology represents a core component in integrated pest management decision-making. In Taiwan, peanut (Arachis hypogaea L.) is an important miscellaneous crop, whereas sesbania (Sesbania roxburghii Merr.) is the most frequently used green manure crop. To improve the S. frugiperda management in Taiwan, the demographic characteristics and population simulation of this pest reared on peanut and sesbania leaves were analyzed using the age-stage, two-sex life table theory. The intrinsic rate of increase, finite rate of increase, and net reproductive rate of S. frugiperda were higher when reared on peanut (0.1625 d-1, 1.1764 d-1, 264.9 offspring) than on sesbania (0.0951 d-1, 1.0997 d-1, and 30.3 offspring). Population projection of S. frugiperda on peanut demonstrated that this crop is a more suitable host plant than sesbania. Yet, this suboptimal host still assures an increasing trend of more than 357-fold individuals in 75 d, from the initial cohort of 10 eggs. Our data suggest that green manure plants in fallowing fields may support the pest's survival all year round, and may be responsible for a successful establishment and unexpected outbreaks of this invasive pest on the neighboring crops in Taiwan. Our study thus highlights the importance of assessing the population dynamics and areawide pest management of an invasive polyphagous pest on a noneconomic crop to mitigate the potential risk of reinfestation and thus outbreaks.

Carbohydrate metabolism is a determinant for the host specificity of baculovirus infections

Baculoviruses Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) and Bombyx mori nucleopolyhedrovirus (BmNPV) have highly similar genome sequences but exhibit no overlap in their host range. After baculovirus infects nonpermissive larvae (e.g., AcMNPV infecting B. mori or BmNPV infecting Spodoptera litura), we found that stored carbohydrates, including hemolymph trehalose and fat body glycogen, are rapidly transformed into glucose; enzymes involved in glycolysis and the TCA cycle are upregulated and produce more ATP; adenosine signaling that regulates glycolytic activity is also increased. Subsequently, phagocytosis in cellular immunity and the expression of genes involved in humoral immunity increase significantly. Moreover, inhibiting glycolysis and the expression of gloverins in nonpermissive hosts increased baculovirus infectivity, indicating that the stimulated energy production is designed to support the immune response against infection. Our study highlights that alteration of the host's carbohydrate metabolism is an important factor determining the host specificity of baculoviruses, in addition to viral factors.

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Nonpermissive infections by AcMNPV and BmNPV alter host carbohydrate metabolism

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Increased carbohydrate metabolism produces energy to launch immune responses

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Immune responses including antimicrobial peptide production inhibit virus infection

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Host metabolic alterations affect the determination of virus's host specificity

Deformed wing virus infection affects the neurological function of Apis mellifera by altering extracellular adenosine signaling

Deformed wing virus (DWV) infection is believed to be closely associated with colony losses of honeybee (Apis mellifera) due to reduced learning and memory of infected bees. The adenosine (Ado) pathway is important for maintaining immunity and memory function in animals, and it enhances antivirus responses by regulating carbohydrate metabolism in insects. Nevertheless, its effect on the memory of invertebrates is not yet clear. This study investigated how the Ado pathway regulates energy metabolism and memory in honeybees following DWV infection. Decreased Ado receptor (Ado-R) expression in the brain of infected bees resulted in a carbohydrate imbalance as well as impairments of glutamate-glutamine (Glu-Gln) cycle and long-term memory. Dietary supplementation with Ado not only increased the brain energy metabolism but also rescued long-term memory loss by upregulating the expression of memory-related genes. The present study demonstrated the regulation of the Ado pathway upon DWV infection and provides insights into the mechanisms underlying energy regulation and the neurological function of honeybees.

Real-time monitoring of deformed wing virus-infected bee foraging behavior following histone deacetylase inhibitor treatment

Impairment in the learning/memory behavior of bees is responsible for the massive disappearance of bee populations and its consequent agricultural economic losses. Such impairment might be because of o both pesticide exposure and pathogen infection, with a key contributor deformed wing virus (DWV). The present study found that sodium butyrate (NaB) significantly increased survival and reversed the learning/memory impairment of DWV-infected bees. A next-generation sequencing analysis showed that NaB affected the expression of genes involved in glycolytic processes and memory formation, which were suppressed by DWV infection. In addition, we performed a large-scale movement tracking experiment by using a wireless sensor network-based automatic real-time monitoring system and confirmed that NaB could improve the homing ability of DWV-infected bees. In short, we demonstrated the mechanism of how epigenetic regulation can resume the memory function of honeybees and suggest strategies for applying NaB to reduce the incidence of colony losses.

MicroRNAs from Snellenius manilae bracovirus regulate innate and cellular immune responses of its host Spodoptera litura

To avoid inducing immune and physiological responses in insect hosts, parasitoid wasps have developed several mechanisms to inhibit them during parasitism, including the production of venom, specialized wasp cells, and symbioses with polydnaviruses (PDVs). These mechanisms alter the host physiology to give the wasp offspring a greater chance of survival. However, the molecular mechanisms for most of these alterations remain unclear. In the present study, we applied next-generation sequencing analysis and identified several miRNAs that were encoded in the genome of Snellenius manilae bracovirus (SmBV), and expressed in the host larvae, Spodoptera litura, during parasitism. Among these miRNAs, SmBV-miR-199b-5p and SmBV-miR-2989 were found to target domeless and toll-7 in the host, which are involved in the host innate immune responses. Microinjecting the inhibitors of these two miRNAs into parasitized S. litura larvae not only severely decreased the pupation rate of Snellenius manilae, but also restored the phagocytosis and encapsulation activity of the hemocytes. The results demonstrate that these two SmBV-encoded miRNAs play an important role in suppressing the immune responses of parasitized hosts. Overall, our study uncovers the functions of two SmBV-encoded miRNAs in regulating the host innate immune responses upon wasp parasitism.

Factors influencing different types of malocclusion and arch form-A review

AIM

This review intends to highlight malocclusion as a multifactorial issue and review the different factors that influence different types of malocclusion and arch form.

METHODS

An online article search was performed on the factors influencing malocclusion and arch form from January 1990 through April 2020. The search was performed within the Google, Rutgers library, PubMed, MEDLINE databases via OVID using the keywords mentioned in the PubMed and MeSH headings for the English language published articles January 1990 through April 2020, which evaluated different factors that influence malocclusion and arch form.

RESULTS

Of the 300 articles found in initial search results, 31 articles met the inclusion criteria set for this review. These 31 studies were directly related to the factors that impact malocclusion and different arch forms.

CONCLUSION

Genetic inheritance, genetic mutations, age, gender, ethnicity, dental anomalies like macrodontia, congenital diseases, muscular diseases, hormone imbalance, and human behaviour are all factors that influence malocclusion and arch forms. The elements within the individual's control like behaviours can aid in preventing malocclusion. However, it seems as if the underlying reason for most of these factors indicates that malocclusion is a by-product of genetics and pathology.

Adenosine Receptor Modulates Permissiveness of Baculovirus (Budded Virus) Infection via Regulation of Energy Metabolism in Bombyx mori

Although the modulation of host physiology has been interpreted as an essential process supporting baculovirus propagation, the requirement of energy supply for host antivirus reactions could not be ruled out. Our present study showed that metabolic induction upon AcMNPV (budded virus) infection of Bombyx mori stimulated virus clearance and production of the antivirus protein, gloverin. In addition, we demonstrated that adenosine receptor signaling (AdoR) played an important role in regulating such metabolic reprogramming upon baculovirus infection. By using a second lepidopteran model, Spodoptera frugiperda Sf-21 cells, we demonstrated that the glycolytic induction regulated by adenosine signaling was a conservative mechanism modulating the permissiveness of baculovirus infection. Another interesting finding in our present study is that both BmNPV and AcMNPV infection cause metabolic activation, but it appears that BmNPV infection moderates the level of ATP production, which is in contrast to a dramatic increase upon AcMNPV infection. We identified potential AdoR miRNAs induced by BmNPV infection and concluded that BmNPV may attempt to minimize metabolic activation by suppressing adenosine signaling and further decreasing the host's anti-baculovirus response. Our present study shows that activation of energy synthesis by adenosine signaling upon baculovirus infection is a host physiological response that is essential for supporting the innate immune response against infection.

Snellenius manilae bracovirus suppresses the host immune system by regulating extracellular adenosine levels in Spodoptera litura

Sufficient energy supply to the host immune system is important for resisting pathogens. Therefore, during pathogen infection, the host metabolism is reassigned from storage, growth, and development to the immune system. Previous studies in Drosophila melanogaster have demonstrated that systemic metabolic switching upon an immune challenge is activated by extracellular adenosine signaling, modulating carbohydrate mobilization and redistributing energy to the hemocytes. In the present study, we discovered that symbiotic virus (SmBV) of the parasitoid wasp Snellenius manilae is able to down-regulate the extracellular adenosine of its host, Spodoptera litura, to inhibit metabolism switching. The decreased carbohydrate mobilization, glycogenolysis, and ATP synthesis upon infection results in the host being unable to supply energy to its immune system, thus benefitting the development of wasp larvae. When we added adenosine to the infected S. litura larvae, we observed enhanced host immune responses that decreased the pupation rate of S. manilae. Previous studies showed that after pathogen infection, the host activates its adenosine pathway to trigger immune responses. However, our results suggest a different model: we found that in S. manilae, SmBV modulates the host adenosine pathway such that wasp eggs and larvae can evade the host immune response.

Automated 3D-printed unibody immunoarray for chemiluminescence detection of cancer biomarker proteins

A low cost three-dimensional (3D) printed clear plastic microfluidic device was fabricated for fast, low cost automated protein detection. The unibody device features three reagent reservoirs, an efficient 3D network for passive mixing, and an optically transparent detection chamber housing a glass capture antibody array for measuring chemiluminescence output with a CCD camera. Sandwich type assays were built onto the glass arrays using a multi-labeled detection antibody-polyHRP (HRP = horseradish peroxidase). Total assay time was ∼30 min in a complete automated assay employing a programmable syringe pump so that the protocol required minimal operator intervention. The device was used for multiplexed detection of prostate cancer biomarker proteins prostate specific antigen (PSA) and platelet factor 4 (PF-4). Detection limits of 0.5 pg mL-1 were achieved for these proteins in diluted serum with log dynamic ranges of four orders of magnitude. Good accuracy vs. ELISA was validated by analyzing human serum samples. This prototype device holds good promise for further development as a point-of-care cancer diagnostics tool.

Chaperones and intimate physical examinations: what do male and female patients want?

INTRODUCTION

Many studies of patients' perception of a medical chaperone have focused on female patients; that of male patients are less well studied. Moreover, previous studies were largely based on patient populations in English-speaking countries. Therefore, this study was conducted to investigate the perception and attitude of male and female Chinese patients to the presence of a chaperone during an intimate physical examination.

METHODS

A cross-sectional guided questionnaire survey was conducted on a convenient sample of 150 patients at a public teaching hospital in Hong Kong.

RESULTS

Over 90% of the participants considered the presence of a chaperone appropriate during intimate physical examination, and 84% felt that doctors, irrespective of gender, should always request the presence of a chaperone. The most commonly cited reasons included the availability of an objective account should any legal issue arise, protection against sexual harassment, and to provide psychological support. This contrasted with the experience of those who had previously undergone an intimate physical examination of whom only 72.6% of women and 35.7% of men had reportedly been chaperoned. Among female participants, 75.0% preferred to be chaperoned during an intimate physical examination by a male doctor, and 28.6% would still prefer to be chaperoned when being examined by a female doctor. Among male participants, over 50% indicated no specific preference but a substantial minority reported a preference for chaperoned examination (21.2% for male doctor and 25.8% for female doctor).

CONCLUSIONS

Patients in Hong Kong have a high degree of acceptance and expectations about the role of a medical chaperone. Both female and male patients prefer such practice regardless of physician gender. Doctors are strongly encouraged to discuss the issue openly with their patients before they conduct any intimate physical examination.

Paper-based electrochemical immunoassay for rapid, inexpensive cancer biomarker protein detection

Inexpensive, reusable electrochemical sensor chips were fabricated from gold CDs. All reagents were loaded onto a paper disk sequentially, then placed on the chip to detect cancer biomarker prostate specific antigen (PSA) in serum at pg mL-1 levels in ∼15 mins.

Simulation of A Low Loss Optical Modulator for Fabrication in Simox Material

A novel phase modulator has been designed and analysed, assuming fabrication in a silicon-on-insulator material such as SIMOX. The proposed modulator is based upon a transverse p-i-n structure, utilising the plasma dispersion effect to produce the desired refractive index change in an optical rib waveguide. The device has been studied using the MEDICI two dimensional device simulation package to optimise the injected carrier interaction with the propagating optical mode. Whilst the device is designed to support a single optical mode, it measures several micrometers in cross sectional dimensions, thereby simplifying fabrication and allowing efficient coupling to other single mode devices such as optical fibers. Furthermore the device has an extremely high figure of merit, predicting over 200 degrees of induced phase shift per volt per mm. This implies a short active length together with a low power requirement.

Flavin specificity and subunit interaction of Vibrio fischeri general NAD(P)H-flavin oxidoreductase FRG/FRase I

Apoenzyme of the major NAD(P)H-utilizing flavin reductase FRG/FRase I from Vibrio fischeri was prepared. The apoenzyme bound one FMN cofactor per enzyme monomer to yield fully active holoenzyme. The FMN cofactor binding resulted in substantial quenching of both the flavin and the protein fluorescence intensities without any significant shifts in the emission peaks. In addition to FMN binding (K(d) 0.5 microM at 23 degrees C), the apoenzyme also bound 2-thioFMN, FAD and riboflavin as a cofactor with K(d) values of 1, 12, and 37 microM, respectively, at 23 degrees C. The 2-thioFMN containing holoenzyme was about 40% active in specific activity as compared to the FMN-containing holoenzyme. The FAD- and riboflavin-reconstituted holoenzymes were also catalytically active but their specific activities were not determined. FRG/FRase I followed a ping-pong kinetic mechanism. It is proposed that the enzyme-bound FMN cofactor shuttles between the oxidized and the reduced form during catalysis. For both the FMN- and 2-thioFMN-containing holoenzymes, 2-thioFMN was about 30% active as compared to FMN as a substrate. FAD and riboflavin were also active substrates. FRG/FRase I was shown by ultracentrifugation at 4 degrees C to undergo a monomer-dimer equilibrium, with K(d) values of 18.0 and 13.4 microM for the apo- and holoenzymes, respectively. All the spectral, ligand equilibrium binding, and kinetic properties described above are most likely associated with the monomeric species of FRG/FRase I. Many aspects of these properties are compared with a structurally and functionally related Vibrio harveyi NADPH-specific flavin reductase FRP.

Nuclear localization of E-cadherin expression in Merkel cell carcinoma

CONTEXT

Cadherins are cell-cell adhesion proteins that act as tumor suppressor genes and have a critical role in cell sorting and tissue formation during organogenesis. The pattern of cadherin expression constitutes a useful diagnostic and prognostic tool in the evaluation of tumors and for determining the histogenesis of tumor cells. We have previously characterized the cell types of several tumors based on the expression of individual cadherins.

OBJECTIVE

To investigate the expression of cadherins in Merkel cell carcinomas.

DESIGN

Paraffin immunohistochemical analysis of the 3 best-studied cadherins was performed on 35 cases of Merkel cell carcinoma.

RESULTS

E-cadherin was expressed in 34 (97%) of 35 Merkel cell carcinomas examined, N-cadherin was expressed in 22 (63%) of 35 cases, and P-cadherin was expressed in 15 (43%) of 35 cases. This frequency of cadherin expression was similar to a group of small cell and neuroendocrine tumors from other primary sites. Interestingly, the localization of E-cadherin expression was unique in Merkel cell carcinomas compared with other primary neuroendocrine tumors. Merkel cell carcinomas showed marked preference for nuclear versus membrane localization, whereas small cell tumors from other sites showed fewer cases of nuclear E-cadherin expression. The nuclear localization of E-cadherin did not correlate with cadherin-associated protein beta-catenin nuclear expression.

CONCLUSIONS

Our findings show that E-cadherin is the most frequently expressed cadherin in Merkel cell carcinoma, followed in frequency by N-cadherin then P-cadherin. The pattern of nuclear E-cadherin expression is more frequent for Merkel cell carcinoma than small cell tumors of other primary sites. These observations suggest that E-cadherin expression and function are altered in Merkel cell carcinoma, and this finding has potential use in the differential diagnosis of these tumors.

Epidermal growth factor receptor vIII enhances tumorigenicity in human breast cancer

Epidermal growth factor receptor vIII (EGFRvIII) is a tumor-specific, ligand-independent, constitutively active variant of the EGFR. Its expression has been detected in gliomas and various other human malignancies. To more fully characterize the function and potential biological role of EGFRvIII in regulating cell proliferation and in tumorigenesis, we transfected EGFRvIII cDNA into a nontumorigenic, interleukin 3 (IL-3)-dependent murine hematopoietic cell line (32D cells). We observed 32D cells expressing high levels of EGFRvIII (32D/EGFRvIII P5) to be capable of abrogating the IL-3-dependent pathway in the absence of ligands. In contrast, the parental cells, 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells, all depended on IL-3 or EGF-like ligands for growth. 32D/EGFRvIII P5 cells subjected to long-term culture conditions in the absence of IL-3 revealed further elevation of EGFRvIII expression levels. These results suggested that the IL-3-independent phenotype is mediated by EGFRvIII. The level of expression is a critical driving force for the IL-3-independent phenotype. Dose-response analysis revealed 32D/EGFRvIII cells to require 500-fold higher concentrations (50 ng/ml) of EGF to further stimulate the EGF-mediated proliferation than in the 32D/EGFR cells (100 pg/ml). Similar effects were also observed in beta-cellulin-mediated proliferation. Moreover, 32D cells expressing high levels of EGFRvIII formed large tumors in nude mice, even when no exogenous EGF ligand was administered. In contrast, no tumors grew in mice injected with 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells or low-expressing clone 32D/EGFRvIII C2 cells or the parental 32D cells. The changes of the ligand specificity support the notion for an altered conformation of EGFRvIII to reveal an activated ligand-independent oncoprotein with tumorigenic activity analogous to v-erbB. These studies clearly demonstrate that EGFRvIII is capable of transforming a nontumorigenic, IL-3-dependent murine hematopoietic cell line (32D cells) into an IL-3-independent and ligand-independent malignant phenotype in vitro and in vivo. To delineate the biological significance of EGFRvIII in human breast cancer, we expressed EGFRvIII in the MCF-7 human breast cancer cell line. Expression of EGFRvIII in MCF-7 cells produced a constitutively activated EGFRvIII receptor. Expression of EGFRvIII in MCF-7 cells also elevated ErbB-2 phosphorylation, presumably through heterodimerization and cross-talk. These MCF-7/EGFRvIII transfectants exhibited an approximately 3-fold increase in colony formation in 1% serum with no significant effect observed at higher percentages of serum. A similar result was also seen in anchorage-dependent assays. Furthermore, EGFRvIII expression significantly enhanced tumorigenicity of MCF-7 cells in athymic nude mice with P < 0.001. Collectively, these results provide the first evidence that EGFRvIII could play a pivotal role in human breast cancer progression.

Probing the mechanisms of the biological intermolecular transfer of reduced flavin

NAD(P)H-flavin oxidoreductases [flavin reductases (FR)] are a class of enzymes capable of producing reduced flavin for bacterial bioluminescence and other biological processes. Bacterial luciferase utilizes oxygen, reduced FMN (FMNH2) and a long-chain aliphatic aldehyde as substrates for light emission. The Vibrio harveyi luciferase and FRP (for which we have cloned the gene and determined the crystal structure) is a model for the elucidation of the reduced flavin transfer mechanism using both a flavin reductase single-enzyme assay monitoring the NADPH oxidation and a flavin reductase-luciferase coupled assay measuring bioluminescence intensity or quantum output. The FRP exhibits a ping-pong kinetic pattern in the single-enzyme assay but changes to a sequential pattern in the coupled assay. Furthermore, FMN at >2x10(-6) mol/L reduced both the light intensity and quantum yield of the coupled reaction by noncompetitively inhibiting NADPH and competitively inhibiting luciferase. These results support a scheme in which the luciferase forms specific complex(es) with FRP. Indeed, such complexes were shown by fluorescence anisotropy to exist between luciferase and monomeric FRP either in the holo- or apoenzyme form. Furthermore, the reduced flavin cofactor of FRP is transferred directly to luciferase for bioluminescence, whereas the reduced flavin product of FRP is inefficient in supporting the luminescence reaction. The mechanism of reduced flavin transfer is apparently flavin and flavin reductase specific.

Anti-HER2 antibody enhances the growth inhibitory effect of anti-oestrogen on breast cancer cells expressing both oestrogen receptors and HER2

Anti-oestrogen is effective for the treatment of oestrogen receptor (ER)-positive breast carcinomas, but most of these tumours become resistant to anti-oestrogen. It has been suggested that anti-oestrogen therapy may induce a HER2 signalling pathway in breast cancer cells and this may cause resistance to anti-oestrogen. Thus, it is conceivable that combined therapy with anti-oestrogen and anti-HER2 antibody might be more effective. In the present study, we investigated the effect of combined treatment with a humanized anti-HER2 monoclonal antibody, rhumAbHER2 (trastuzumab), and an anti-oestrogen, ICI 182,780, on the cell growth of three human breast cancer cell lines which respectively express different levels of ER and HER2. The combined treatment enhanced the growth inhibitory effect on ML-20 cells, which express a high level of ER and a moderate level of HER2, but showed no additive effect on either KPL-4 cells, which express no ER and a moderate level of HER2, or MDA-MB-231 cells, which express no ER and a low level of HER2. It is also suggested that both the antibody and anti-oestrogen induce a G1-S blockade and apoptosis. These findings indicate that combined treatment with anti-HER2 antibody and anti-oestrogen may be useful for the treatment of patients with breast cancer expressing both ER and HER2.

Ribozyme-mediated down-regulation of ErbB-4 in estrogen receptor-positive breast cancer cells inhibits proliferation both in vitro and in vivo

ErbB-4 is a recently discovered member of the class I receptor tyrosine kinase family (ErbB). Little is known about its expression and its importance in human malignancy. To delineate the biological function of ErbB-4 receptors in breast cancer, we used a hammerhead ribozyme strategy to achieve down-regulation of ErbB-4 receptors in various breast cancer cell lines. We observed that down-regulation of ErbB-4 in estrogen receptor-positive (ER+) human breast cancer cell lines (MCF-7 and T47D), which express relatively high levels of ErbB-4, significantly inhibited colony formation. No effects were observed in estrogen receptor-negative (ER-) MDA-MB-453 cells, which express low levels of endogenous ErbB4 and high levels of ErbB-2 and ErbB-3. This occurred despite the fact that fluorescence-activated cell sorter analysis of these latter cells revealed that the expression of the ErbB-4 receptor was completely abrogated by ribozyme treatment. Furthermore, down-regulation of ErbB-4 in T47D and MCF-7 cells significantly inhibited tumor formation in athymic nude mice (P < 0.03 and P < 0.001, respectively). In addition, NRG-stimulated phosphorylation of ErbB-4- and NRG-induced colony formation was significantly reduced in ribozyme-transfected T47D cells. These data provide the first evidence that elevation of ErbB-4 expression plays a role in the proliferation of some ER+ human breast cancer cell lines (T47D and MCF-7) that express high levels of ErbB-4. We have also investigated the expression of ErbB-4 in human primary breast carcinoma specimens, using immunohistochemical staining with an anti-ErbB-4 monoclonal antibody. ErbB-4 expression was found in 60% of the 50 primary breast tumors examined, and high intense immunoreactivity of ErbB-4 was detected in 18% of these primary breast tumors. ErbB-4 receptor expression appeared to correlate with ER+ primary breast tumors. A similar correlation was also observed in the human breast cancer cell lines. These results provide a better understanding of the biological significance of ErbB-4 receptor in breast cancer. Our data suggest that elevation of the ErbB-4 receptor plays a role in ER+ breast cancer cell proliferation. Moreover, ribozyme technology provides a useful tool to delineate the role of a particular gene product.

P+HA- charge recombination reaction rate constant in Rhodobacter sphaeroides reaction centers is independent of the P/P+ midpoint potential

The kinetics of the P+HA- (oxidized donor, reduced bacteriopheophytin acceptor) recombination reaction was measured in a series of reaction center mutants of Rhodobacter sphaeroides with altered P/P+ midpoint potentials between 410 and 765 mV. The time constant for P+HA- recombination was found to range between 14 and 26 ns and was essentially independent of P/P+ midpoint potential. Previous work has shown that the time constant for initial electron transfer in these mutants at room temperature is also only weakly dependent on the P/P+ midpoint potential, ranging from about 2.5 ps to about 50 ps. These results, taken together, imply that heterogeneity in the P/P+ midpoint potential within the reaction center population is not likely the dominant cause of the substantial kinetic complexity observed in the decay of the excited singlet state of P on the picosecond to nanosecond time scale. In addition, the pathway of P+HA- decay appears to be direct or via P+BA- rather than proceeding back through P, even in the highest-potential mutant, as is evident from the fact that the rate of P+HA- recombination is unaltered by pushing P+HA- much closer to P in energy. Finally, the midpoint potential independence of the P+HA- recombination rate constant suggests that the slow rate of P+HA- recombination arises from an inherent limitation in the maximum rate of this process rather than because it occurs in the inverted region of a classical Marcus rate vs free energy curve.

Cripto-1 indirectly stimulates the tyrosine phosphorylation of erb B-4 through a novel receptor

Cripto-1 (CR-1) is a recently discovered protein of the epidermal growth factor family that fails to directly bind to any of the four known erb B type 1 receptor tyrosine kinases. The present study demonstrates that CR-1 indirectly induces tyrosine phosphorylation of erb B-4 but not of the epidermal growth factor-related receptors erb B-2 and erb B-3 in different mouse and human mammary epithelial cell lines. In addition, down-regulation of erb B-4 in NMuMG mouse mammary epithelial cells and in T47D human breast cancer cells, using an anti-erb B-4 blocking antibody or a hammerhead ribozyme vector targeted to erb B-4 mRNA, impairs the ability of CR-1 to fully activate mitogen-activated protein kinase. Finally, chemical cross-linking of 125I-CR-1 to mouse and human mammary epithelial cell membranes results in the labeling of two specific bands with a molecular weight of 130 and 60 kDa, suggesting that the CR-1 receptor represents a novel receptor structurally unrelated to any of the known type I receptor tyrosine kinases. In conclusion, these data demonstrate that CR-1, upon binding to an unknown receptor, can enhance the tyrosine kinase activity of erb B-4 and that a functional erb B-4 receptor is required for CR-1-induced MAPK activation.

Isolation and characterization of a new human breast cancer cell line, KPL-4, expressing the Erb B family receptors and interleukin-6

A new human breast cancer cell line, KPL-4, was recently isolated from the malignant pleural effusion of a breast cancer patient with an inflammatory skin metastasis. This cell line can be cultured under serum-free conditions and is tumorigenic in female athymic nude mice. Flow cytometric analysis revealed the expression of Erb B-1, -2 and -3. Dot blot hybridization showed a 15-fold amplification of the erb B-2. Reverse transcription-polymerase chain reaction analysis showed a detectable level of mRNA expression of all the Erb B family receptors. In addition, all the receptors were autophosphorylated under a serum-supplemented condition. Unexpectedly, transplanted KPL-4 tumours induced cachexia of recipient mice. A high concentration of interleukin-6 (IL-6) was detected in both the culture medium and the serum of mice. The weight of tumours significantly correlated with the serum IL-6 level. The antiproliferative effect of a humanized anti-Erb B-2 monoclonal antibody, rhuMAbHER2, was investigated. This antibody significantly inhibited the growth of KPL-4 cells in vitro but modestly in vivo. Loss of mouse body weight was partly reversed by rhuMAbHER2. These findings suggest that KPL-4 cells may be useful in the development of new strategies against breast cancer overexpressing the Erb B family receptors and against IL-6-induced cachexia.

Dysregulated synthesis of intracellular type 1 and type 2 cytokines by T cells of patients with cutaneous T-cell lymphoma

Mycosis fungoides (MF) and Sezary syndrome (SS) are the two main clinical entities of cutaneous T-cell lymphoma (CTCL). As the disease progresses from MF to SS, a switch from a type 1 (interleukin [IL]-2 and gamma interferon [IFN-gamma]) to a type 2 (IL-4) cytokine production profile occurs. Although roles for type 1 and type 2 cytokines in the pathogenesis of CTCL have been proposed, the cellular origins of these cytokines are unclear. Using flow cytometry to identify individual T-cell subsets, we studied cytokine synthesis by the T cells of 13 patients with SS and 12 with MF and 9 hematologically healthy donors. Upon activation with phorbol 12-myristate 13-acetate (PMA), the numbers of T cells synthesizing IL-2 were similar for all study groups. Whereas the predominant T-cell producing IL-2 in healthy donors and in those with MF was CD7(+), in patients with SS, it was CD7(-). Although the number of IL-4(+) CD4(+) T cells was low for all study groups, there was a significantly higher number of IL-4(+) CD8(+) T cells in patients with MF than in those with SS or healthy donors. There was a decline in the number of IFN-gamma-producing T cells in CTCL donors compared to that in healthy donors. More importantly, there was a significant decrease in the number of IFN-gamma-producing T cells with disease progression from MF to SS. The inability of these T cells to synthesize IFN-gamma may have prognostic value in CTCL, since it may be responsible for the progression of the disease from MF to SS.

ErbB-4 ribozymes abolish neuregulin-induced mitogenesis

The epidermal growth factor-like receptor tyrosine kinase (ErbB) family is frequently overexpressed in a variety of human carcinomas, including breast cancer. To assist in characterizing the role of ErbB-4 in breast cancer, we generated three specific hammerhead ribozymes targeted to the ErbB-4 mRNA. These ribozymes, Rz6, Rz21, and Rz29, efficiently catalyzed the specific cleavage of ErbB-4 message in a cell-free system. We demonstrated that the neuregulin-induced mitogenic effect was abolished in ribozyme Rz29- and Rz6-transfected 32D/ErbB-4 cells. Inhibition of mitogenesis was characterized by ribozyme-mediated down-regulation of ErbB-4 expression. In addition, we provide the first evidence that different threshold levels of ErbB-4 expression and activation correlate with different responses to neuregulin stimulation. High levels of ErbB-4 expression, phosphorylation, and homodimerization are necessary for neuregulin-stimulated, interleukin 3-independent cell proliferation in the 32D/E4 cells. In the case of Rz29-transfected 32D/E4 cells, low levels of ErbB-4 expression allowed neuregulin-induced phosphorylation but were insufficient to couple the activated receptor to cellular signaling. Furthermore, expression of the functional ErbB-4 ribozyme in T47D human breast carcinoma cells led to a down-regulation of endogenous ErbB-4 expression and a reduction of anchorage-independent colony formation. These studies support the use of ErbB-4 ribozymes to define the role of ErbB-4 receptors in human cancers.

Involvement of heregulin-beta2 in the acquisition of the hormone-independent phenotype of breast cancer cells

The erbB-2 receptor plays an important role in the prognosis of breast cancer. Amplification or overexpression of the erbB-2 proto-oncogene has been detected in 30% of breast cancers and is associated with poor patient prognosis. The significance of erbB-3 and erbB-4 in breast cancer is not yet known. The discovery of the growth factor heregulin (HRG) has allowed us to investigate a number of biological events that are regulated by erbB-2, -3, and -4 signal transduction. To determine the role of HRG in breast cancer tumor progression, we have developed an in vitro/in vivo model. We transfected HRG cDNA into the estrogen receptor (ER)-positive breast cancer cell line, MCF-7, and studied these cells as they progressed from a hormone-dependent to -independent phenotype. The biochemical and biological characteristics presented here demonstrate that overexpression of HRG induces morphological changes in MCF-7 cells as well as erbB-2, erbB-3, and erbB-4 autophosphorylation. MCF-7/ heregulin-transfected cells, which express relatively high levels of HRG, developed estrogen independence and resistance to antiestrogens in vitro and in vivo. This is consistent with a more aggressive hormone-independent phenotype. In contrast with control parental/wild-type cells, estradiol-mediated down-regulation of erbB-2 expression is blocked completely in this particular model system. These results indicate that HRG plays a role in the disruption of ER function. When a transient transfection with an ERE-CAT construct was introduced into these HRG-transfected MCF-7 cells, we observed that the ER was transcriptionally inactive. This suggests that ER signaling is altered in HRG-transfected cells. We observed that overexpression of HRG induces a more aggressive, hormone-independent phenotype that is most likely directly related to the constitutive activation of the erbB-2, erbB-3, and erbB-4 receptor signaling cascade. The data presented here suggest a close cross-regulation between the erbB-2/4 receptors and ER and provide new insights into the mechanism by which breast cancer cells acquire a hormone-independent phenotype.

Malignant myoepithelioma of the parotid gland: case report and review of the literature

A 62-year-old male with a myoepithelioma of the right parotid gland was treated with surgical excision followed by adjuvant radiation therapy. Prior to the completion of radiation therapy, the patient developed progressive disease at local, regional, and distant metastatic sites. Combined modality treatment with radiation and chemotherapy resulted in a significant but transient shrinkage of the tumours at all sites. The patient succumbed to metastatic disease 212 days following the diagnostic biopsy. This case illustrates several of the distinctive clinical and pathological characteristics of this rare tumour.

Catalytically active forms of the individual subunits of Vibrio harveyi luciferase and their kinetic and binding properties

Contradictory findings have recently been reported regarding the (in)abilities of individual subunits of the Vibrio harveyi alpha beta dimeric luciferase to catalyze bioluminescence. We have produced individual alpha and beta subunits separately in Escherichia coli JM109 cells by recombinant DNA techniques. Both subunits were purified to more than 90% homogeneity and found to be catalytically active, with their general catalytic properties and the specific activities similar to those reported earlier (Sinclair, J. F., Waddle, J. J., Waddill, E. F., and Baldwin, T. O. (1993) Biochemistry 32, 5036-5044). Individual subunits were significantly distinct from the native luciferase with respect to inactivations by trypsin and N-ethylmaleimide, and the stability of the flavin 4a-hydroperoxide intermediate. The active species in isolated alpha and beta samples were each the predominant protein species, corresponding to a 42,000 M(r) alpha monomer and a 67,000 M(r) beta dimer, respectively. These findings clearly indicate that the activities of the individual subunits are not due to trace contaminations of the respective counter subunits. The much reduced specific activities of the individual subunits are, in part, a consequence of diminished abilities to oxidize the aldehyde substrate. Kinetic and equilibrium measurements indicate that alpha and beta 2 each contained a reduced flavin site, an aldehyde substrate site, and an aldehyde inhibitor site. The on and off rates of the decanal inhibitor binding were substantially slower than the bindings of decanal and reduced riboflavin 5'-phosphate substrates. These findings are consistent with a scheme that the aldehyde inhibitor blocks the binding of the reduced flavin substrate.

Nonlactational breast infection

Experiences with the treatment and results of treatment of 96 patients with acute or chronic periareolar abscesses are presented. A mammillary sinus or fistula was demonstrable in virtually every instance. The key to preventing recurrence is demonstrating and either removing or unroofing the sinus tract.

Neuroblastoma as a prominent component of a mixed germ cell tumor of testis

BACKGROUND

Primitive neuroectodermal tissue in teratomas of testis has been reported in the literature. A mixed germ cell tumor of testis with a prominent neuroblastoma component dictating the clinical behavior was found to be unique.

METHODS

Tissue sections were stained with hematoxylin and eosin, and immunohistochemical, ultrastructural, cytogenetic, and flow cytometric analyses were performed on the primitive neuroectodermal component of the testicular mass. Follow-up results at 2.5 years are included.

RESULTS

The microscopic findings on hematoxylin and eosin slides showed cells composing the majority of the neoplasm to have features of neuroblastoma. The immunohistochemical stains showed positivity for neuron-specific enolase in the cells comprising the neuroblastoma, and transmission electron microscopic study corroborated these findings by demonstrating microtubules and rare membrane-limited, dense-core granules in the cytoplasm. Flow cytometry showed a hypertetraploid population with a large aneuploid DNA content. Cytogenetics revealed a hypertriploid modal number of 74 chromosomes. The clinical features were dictated by the neuroblastoma component in a fashion similar to that of adult neuroblastomas and responded to the chemotherapeutic regimen designed for treating neuroblastoma.

CONCLUSIONS

The neuroblastoma component proved to be more aggressive than the other elements of this neoplasm. This finding suggests that mixed germ cell tumors showing a large neuroblastoma component should be treated promptly and aggressively with chemotherapy.

Basaloid squamous cell carcinoma of floor of mouth

BACKGROUND

Only five cases of basaloid squamous cell carcinoma (BSCC), a rare tumor of head and neck, have been reported to involve the floor of mouth.

METHODS

Clinicopathologic and immunohistochemical features of eight BSCC of floor of mouth were studied to evaluate the significance of the basaloid features.

RESULTS

Five patients were male and three were female. Their mean age was 52 years (range, 39-59). At presentation, one patient was diagnosed with Stage II disease, four were diagnosed with Stage III disease, and three were diagnosed with Stage IV disease. Aside from typical squamous differentiation, each patient had a component of basaloid cells arranged in irregular nests, cords, or pseudoglandular spaces with a brisk mitotic rate, myxoid stroma, and marked tendency for perineural invasion. A panel of immunostains yielded the following results: keratin, +8/8; carcinoembryonic antigen, +3/8; and S-100, chromogranin, and neuron-specific enolase were negative. Mucin stains were negative in all cases. Ultrastructural characterization of three BSCC revealed squamous differentiation of the basaloid cells and a peculiar basal membrane-like material in between them. No neurosecretory granules were present. Seven patients underwent surgery; six of them were also treated with postoperative radiation therapy. In two cases, chemotherapy was added at recurrence. One nonresectable patient received radiation and chemotherapy. At the last follow-up, five patients were dead of disease within 13 months from the diagnosis. One patient died of an unknown cause. Two patients were still alive at the time of this report, 4 and 2 months after treatment. Seven patients had recurrent disease. The authors compared these data with a control group of patients with conventional squamous cell carcinoma (SCC).

CONCLUSIONS

The authors' results indicate that BSCC of floor of mouth is an aggressive variant of SCC and is prognostically worse than the conventional SCC, regardless of the grade of the latter.

Basaloid squamous cell carcinoma of floor of mouth

BACKGROUND

Only five cases of basaloid squamous cell carcinoma (BSCC), a rare tumor of head and neck, have been reported to involve the floor of mouth.

METHODS

Clinicopathologic and immunohistochemical features of eight BSCC of floor of mouth were studied to evaluate the significance of the basaloid features.

RESULTS

Five patients were male and three were female. Their mean age was 52 years (range, 39-59). At presentation, one patient was diagnosed with Stage II disease, four were diagnosed with Stage III disease, and three were diagnosed with Stage IV disease. Aside from typical squamous differentiation, each patient had a component of basaloid cells arranged in irregular nests, cords, or pseudoglandular spaces with a brisk mitotic rate, myxoid stroma, and marked tendency for perineural invasion. A panel of immunostains yielded the following results: keratin, +8/8; carcinoembryonic antigen, +3/8; and S-100, chromogranin, and neuron-specific enolase were negative. Mucin stains were negative in all cases. Ultrastructural characterization of three BSCC revealed squamous differentiation of the basaloid cells and a peculiar basal membrane-like material in between them. No neurosecretory granules were present. Seven patients underwent surgery; six of them were also treated with postoperative radiation therapy. In two cases, chemotherapy was added at recurrence. One nonresectable patient received radiation and chemotherapy. At the last follow-up, five patients were dead of disease within 13 months from the diagnosis. One patient died of an unknown cause. Two patients were still alive at the time of this report, 4 and 2 months after treatment. Seven patients had recurrent disease. The authors compared these data with a control group of patients with conventional squamous cell carcinoma (SCC).

CONCLUSIONS

The authors' results indicate that BSCC of floor of mouth is an aggressive variant of SCC and is prognostically worse than the conventional SCC, regardless of the grade of the latter.

Iron regulates the activity of the iron-responsive element binding protein without changing its rate of synthesis or degradation

The iron-responsive element binding protein (IRE-BP) interacts with specific sequence/structure motifs (iron-responsive elements) within the mRNAs encoding ferritin and the transferrin receptor and thereby post-transcriptionally regulates the expression of these two proteins involved in cellular iron homeostasis. The activity of the IRE-BP is itself regulated by iron such that when cells are treated with an iron source, the RNA binding activity is decreased. The expression of recombinant human IRE-BP in murine cells has been examined as have the expressions of the endogenous IRE-BP of both human and rabbit cells. In all cases, iron down-modulated the RNA binding activity of the IRE-BP, but in no instance was this decrease in activity accompanied by a decrease in the level of the protein as judged by quantitative Western blots. Moreover, the rate of synthesis of the IRE-BP and its rate of degradation have been found to be unaltered by iron manipulation of cells in culture. Consistent with IRE-BP regulation occurring post-translationally, the iron regulation of its activity was found to be unaffected by cycloheximide. These data are discussed in terms of a model of IRE-BP regulation involving the modification of the protein's iron-sulfur center.

[Effects of neutral oil of Ligusticum sinense Oliv. on anoxia]

The neutral oil at 2.5 and 5.0g/kg P.O. can significantly decrease the oxygen consumption and prolong survival time for mice, increase the ability of tissues to tolerate anoxia and extend survival time under cerebral ischemic anoxia in mice. It can also inhibit the pituitrin-induced depression of S point in rats.

On the mechanism of the interaction of ketamine and halothane in vitro

1. Electrically induced contraction of guinea pig ileum myenteric plexus-longitudinal muscle was inhibited by ketamine and halothane with IC50s of 2.1 x 10(-4) M and 1.8 v/v% respectively. 2. The inhibitory action of ketamine was partially antagonized by naloxone and the selective kappa antagonist nor-binaltorphimine. 3. The actions of ketamine and halothane were synergistic at high levels of response (above 30% inhibition). 4. The actions of ketamine and halothane became antagonistic after treatment with pertussis toxin. 5. The interaction of ketamine and halothane was similar to the interaction of morphine and halothane.

Reciprocal control of RNA-binding and aconitase activity in the regulation of the iron-responsive element binding protein: role of the iron-sulfur cluster

Several mechanisms of posttranscriptional gene regulation are involved in regulation of the expression of essential proteins of iron metabolism. Coordinate regulation of ferritin and transferrin receptor expression is produced by binding of a cytosolic protein, the iron-responsive element binding protein (IRE-BP) to specific stem-loop structures present in target RNAs. The affinity of this protein for its cognate RNA is regulated by the cell in response to changes in iron availability. The IRE-BP demonstrates a striking level of amino acid sequence identity to the iron-sulfur (Fe-S) protein mitochondrial aconitase. Moreover, the recombinant IRE-BP has aconitase function. The lability of the Fe-S cluster in mitochondrial aconitase has led us to propose that the mechanism by which iron levels are sensed by the IRE-BP involves changes in an Fe-S cluster in the IRE-BP. In this study, we demonstrate that procedures aimed at altering the IRE-BP Fe-S cluster in vitro reciprocally alter the RNA binding and aconitase activity of the IRE-BP. The changes in the RNA binding of the protein produced in vitro appear to match the previously described alterations of the protein in response to iron availability in the cell. Furthermore, iron manipulation of cells correlates with the activation or inactivation of the IRE-BP aconitase activity. The results are consistent with a model for the posttranslational regulation of the IRE-BP in which the Fe-S cluster is altered in response to the availability of intracellular iron and this, in turn, regulates the RNA-binding activity.

Cloning of the cDNA encoding an RNA regulatory protein--the human iron-responsive element-binding protein

Iron-responsive elements (IREs) are stemloop structures found in the mRNAs encoding ferritin and the transferrin receptor. These elements participate in the iron-induced regulation of the translation of ferritin and the stability of the transferrin receptor mRNA. Regulation in both instances is mediated by binding of a cytosolic protein to the IREs. High-affinity binding is seen when cells are starved of iron and results in repression of ferritin translation and inhibition of transferrin receptor mRNA degradation. The IRE-binding protein (IRE-BP) has been identified as an approximately 90-kDa protein that has been purified by both affinity and conventional chromatography. In this report we use RNA affinity chromatography and two-dimensional gel electrophoresis to isolate the IRE-BP for protein sequencing. A degenerate oligonucleotide probe derived from a single peptide sequence was used to isolate a cDNA clone that encodes a protein containing 13 other sequenced peptides obtained from the IRE-BP. Consistent with previous characterization of the IRE-BP, the cDNA encodes a protein of 87 kDa with a slightly acidic pI, and the corresponding mRNA of approximately 3.6 kilobases is found in a variety of cell types. The encoded protein contains a nucleotide-binding consensus sequence and regions of cysteine and histidine clusters. This mRNA is encoded by a single gene on human chromosome 9, a finding consistent with previous localization by functional mapping. The protein contains no previously defined consensus motifs for either RNA or DNA binding. The simultaneous cloning of a different, but highly homologous, cDNA suggests that the IRE-BP is a member of a distinct gene family.

Evidence for allosteric coupling between the ribosome and repressor binding sites of a translationally regulated mRNA

Escherichia coli ribosomal protein S4 is a translational repressor regulating the expression of four ribosomal genes in the alpha operon. In vitro studies have shown that the protein specifically recognizes an unusual mRNA pseudoknot secondary structure which links sequences upstream and downstream of the ribosome binding site for rpsM (S13) [Tang, C. K., & Draper, D. E. (1989) Cell 57, 531]. We have prepared fusions of the rpsM translational initiation site and lacZ that allows us to detect repression in cells in which overproduction of S4 repressor can be induced. Twenty-five mRNA sequence variants have been introduced into the S13-lacZ fusions and the levels of translational repression measured. Sets of compensating base changes confirm the importance of the pseudoknot secondary structure for translational repression. An A residue in a looped, single-stranded sequence is also required for S4 recognition and may contact S4 directly. Comparison of translational repression levels and S4 binding constants for the set of mRNA mutations show that nine mutants are repressed much more weakly than predicted from their affinity for S4; in extreme cases no repression can be detected for variants with unchanged S4 binding. We suggest that the mRNA contains functionally distinct ribosome and repressor binding sites that are allosterically coupled. Mutations can relieve translational repression by disrupting the linkage between the two sites without altering S4 binding. This proposal assigns to the mRNA a more active role in mediating translational repression than found in other translational repression systems.

Vasovasostomy in dogs using the carbon dioxide milliwatt laser: Part II

This is the second study of a two-prong investigation conducted to learn two different aspects of vasovasostomy in dog vas deferens by using the carbon dioxide milliwatt laser. This investigation involves the evaluation of patency and analysis of sperm. Six dogs underwent vasectomy, followed by vasovasostomies performed between 4 and 12 weeks later, utilizing two approximating sutures and welding with the carbon dioxide milliwatt laser. Metal clips were used both for x-ray analysis and localization of the vasovasostomy site. All dogs had pre-vasectomy semen analysis. Following vasectomy each dog underwent ejaculation until azoospermia was obtained. Vasovasostomy was performed and semen was examined. Prior to harvesting, vasography was also obtained. All ejaculates had active sperm noted and 12 of 12 vasograms (100%) revealed patency. The dogs were sacrificed at 4 weeks, 6 weeks, and 8 weeks post-vasovasostomy. The vasovasostomy specimens were studied with electron microscopy and by histological evaluation. The vasovasostomy was completed in under 90 minutes by using this laser-assisted technique. This procedure offers to the urologist a more simplified and reproducible operation that can be performed easily and with a potential decrease in hospital costs.

Carbon dioxide milliwatt laser in the vasovasostomy of vas deferens in dogs: Part I

This is the first arm of a two prong study conducted to learn two different aspects of vasovasostomy in dog vas deferens using the milliwatt carbon dioxide laser. The first study involved the evaluation of patency without collection of sperm. Six dogs were evaluated and all underwent vasectomy and subsequently had vasovasostomies performed between 4 and 12 weeks utilizing two approximating sutures and welding with the milliwatt carbon dioxide laser. Metal clips were used for both X-ray analysis and localization of the vasovasostomy site. In this investigation a vasogram was performed. Dogs were sacrificed at 4, 6, and 8 weeks postvasovasostomy. The vasovasostomy specimens were studied with electron microscopy and histological evaluation. The vasovasostomy was completed in under 120 minutes using this laser-assisted technique and was found to be a viable and promising technique for vasovasostomy.

Angiosarcoma of the axillary vein

Angiosarcoma is a malignant tumor of vascular origin. Malignant primary vein tumors are rare. The case of a 64-year-old patient who underwent a left forequarter amputation for angiosarcoma arising from the left axillary vein, a site not previously described, is presented. Also, the literature is reviewed.

Unusual mRNA pseudoknot structure is recognized by a protein translational repressor

Translation of ribosomal proteins in the alpha operon of E. coli is repressed by one of the encoded proteins, S4; it specifically recognizes an RNA fragment containing the translational initiation site for the first gene in the operon. RNA structure mapping experiments have suggested a pseudoknot structure for the S4 binding site: the loop of a hairpin is base paired to sequences downstream of the hairpin. Here, we systematically test this proposed structure by measuring S4 binding to an extensive set of site-directed mutations that create compensatory base pair changes in potential helices. The pseudoknot folding is confirmed, and two additional, unexpected interactions within the pseudoknot are also detected. The overall structure is an unusual "double pseudoknot" linking a hairpin upstream of the ribosome binding site with sequences 2-10 codons downstream of the initiation codon. Stabilization of this structure by S4 could account for translational repression.

Clear cell carcinoma of the skin: a tricholemmal carcinoma?

We report the light and electron microscopic findings of an unusual, locally aggressive cutaneous clear cell carcinoma involving extensively the left cheek and upper lip of a 61-year-old woman. The patient remained free of recurrence 5 years after wide local excision. Microscopically, the tumor was a poorly circumscribed and deeply invasive clear cell neoplasm characterized by large lobules and convoluted trabeculae of polygonal and columnar cells with palisading of the peripheral cells rimmed by thick basement membranes, and horn microcysts with tricholemmal keratinization. The tumor infiltrated the muscle and the salivary glands. Only slight cytologic atypia and a few mitotic figures were present. No definite ductal differentiation was found. Immunoperoxidase staining for carcinoembryonic and epithelial membrane antigens was negative. Ultrastructurally, the tumor cells were joined by desmosomes, and surrounded by thick basal lamina. The cytoplasm contained large pools of glycogen. Peculiar whorls of tonofilaments and aggregates of needle-shaped and club-shaped structures were observed in a small keratinizing focus. The tumor showed features resembling the outer root sheath of the hair follicle microscopically. Furthermore, the lack of duct-like structures and immunoreactivity of carcinoembryonic antigen tend to favor tricholemmal over sweat gland differentiation in this tumor which possibly represents a rare example of tricholemmal carcinoma.

Tissue carcinoembryonic antigen levels in benign and malignant diseases of the breast

The peroxidase-antiperoxidase histochemical method of staining for tissue carcinoembryonic antigen (CEA) was performed on 20 samples of malignant breast tissue, 20 samples of fibroadenomatous breast tissue, and 15 samples of breast tissue that variably contained minimal fibrosis (N = 7), ductal ectasia (N = 5), and sclerosing adenosis (N = 3; the fibrocystic changes of the breast). The intensity of staining was described to be either negative, weak, intermediate, or strong and was assigned a point value of 1, 2, 3, or 4, respectively. The following weighted average values of tissue CEA were obtained: carcinoma, 3.35 +/- 0.88; fibroadenomas, 2.85 +/- 0.67; fibrocystic changes, 2.13 +/- 0.52. Carcinomatous tissue is likely (55%) to display intense tissue staining, whereas fibrocystic disease (0%) or fibroadenoma (15%) are unlikely to exhibit such a reaction. The tissue CEA content between carcinoma and fibrocystic changes (P less than 0.01), carcinoma and fibroadenoma (P less than 0.01), and fibroadenoma and fibrocystic changes (P less than 0.05) are statistically significant.

Synergistic interaction of morphine and halothane in the guinea pig ileum

The present study describes the effects of halothane on morphine activity in the myenteric plexus-longitudinal muscle preparation of the guinea pig ileum. Morphine and halothane produced a dose-related inhibition of the electrically induced muscle contractions with IC50 of 1.9 X 10(-7) and 1.7 V/V%, respectively. The effects of morphine, but not halothane, were antagonized by naloxone. The IC50 of morphine was decreased in the presence of halothane (0.8-3.0 V/V%). Hill coefficients derived from dose-response curves were less than one for morphine or halothane alone, while it was 1.4 for the combination. The pA2 values (a measure of affinity of the antagonist for the opioid receptor) for naloxone in the absence and presence of halothane (1.6%) were 9.4 and 9.1, respectively. These results indicate that 1) halothane increases the potency of morphine in the guinea pig ileum at clinically relevant concentrations, 2) the interaction between the agents is synergistic, and 3) halothane does not modify the binding of naloxone to opioid receptors, but may affect membrane or intracellular processing of the receptor signal.

Effects of mu receptor agonists and droperidol on motor coordination in mice

The effects of morphine, fentanyl, sufentanil and droperidol on motor coordination in mice were studied. Animals were trained to complete successfully the rotarod test before assessing the effects of drugs. Administration of analgesic doses of the mu agonists morphine, fentanyl and sufentanil did not inhibit motor coordination. Droperidol produced a dose related inhibition of motor coordination. When a subthreshold dose of droperidol was administered followed by an opiate, a significant inhibition of motor coordination was observed. The results indicate that although analgesic doses of mu opioid agonists do not affect motor coordination, their combination with droperidol results in motor incoordination. The mechanisms and/or opioid receptor sub-types involved in this in vivo interaction remain to be established.