Resistance-minimizing strategies for introducing a novel antibiotic for gonorrhea treatment: a mathematical modeling study

Background

Gonorrhea is a highly prevalent sexually transmitted infection and an urgent public health concern due to increasing antibiotic resistance. Only ceftriaxone remains as the recommended treatment in the U.S. The prospect of approval of new anti-gonococcal antibiotics raises the question of how to deploy a new drug to maximize its clinically useful lifespan.

Methods

We used a compartmental model of gonorrhea transmission in the U.S. population of men who have sex with men to compare strategies for introducing a new antibiotic for gonorrhea treatment. The strategies tested included holding the new antibiotic in reserve until the current therapy reached a threshold prevalence of resistance; using either drug, considering immediate and gradual introduction of the new drug; and combination therapy. The primary outcome of interest was the time until 5% prevalence of resistance to both the novel drug and to the current first-line drug (ceftriaxone).

Findings

The reserve strategy was consistently inferior for mitigating antibiotic resistance under the parameter space explored. The reserve strategy was increasingly outperformed by the other strategies as the probability of de novo resistance emergence decreased and as the fitness costs associated with resistance increased. Combination therapy tended to prolong the development of antibiotic resistance and minimize the number of annual gonococcal infections.

Interpretation

Our study argues for rapid introduction of new anti-gonococcal antibiotics, recognizing that the feasibility of each strategy must incorporate cost, safety, and other practical concerns. The analyses should be revisited once robust estimates of key parameters-likelihood of emergence of resistance and fitness costs of resistance for the new antibiotic-are available.

Funding

U.S. Centers for Disease Control and Prevention (CDC), National Institute of Allergy and Infectious Diseases.

An Audit and Comparison of pH, Measured Concentration, and Particulate Matter in Mannitol and Hypertonic Saline Solutions

Background: The preferred hyperosmolar therapy remains controversial. Differences in physical properties such as pH and osmolality may be important considerations in hyperosmolar agent selection. We aimed to characterize important physical properties of commercially available hyperosmolar solutions.

Methods: We measured pH and concentration in 37 commonly-used hyperosmolar solutions, including 20 and 25% mannitol and 3, 5, 14.6, and 23.4% hypertonic saline. pH was determined digitally and with litmus paper. Concentration was determined by freezing point and vapor pressure osmometry. Salinity/specific gravity was measured with portable refractometry. Particulate matter was analyzed with filtration and light microscopy and with dynamic light scattering nephelometry.

Results: pH of all solutions was below physiological range (measured range 4.13–6.80); there was no correlation between pH and solution concentration (R² = 0.005, p = 0.60). Mannitol (mean 5.65, sd 0.94) was less acidic than hypertonic saline (5.16, 0.60). 14/59 (24%) pH measurements and 85/111 concentration measurements were outside manufacturer standards. All 36/36 mannitol concentration measurements were outside standards vs. 48/72 (67%) hypertonic saline (p < 0.0001). All solutions examined on light microscopy contained crystalline and/or non-crystalline particulate matter up to several hundred microns in diameter. From nephelometry, particulate matter was detected in 20/22 (91%) solutions.

Conclusion: We present a novel characterization of mannitol and hypertonic saline. Further research should be undertaken, including research examining development of acidosis following hyperosmolar therapy, the relevance of our findings for dose-response, and the clinical relevance of particulate matter in solution.

CNS inflammation and neurodegeneration: sequelae of peripheral inoculation with spinal cord tissue in rat

OBJECTIVE

Recent research demonstrates that victims of spinal cord injury (SCI) are at increased risk for dementia and that encephalitis can occur as a consequence of isolated SCI. We theorize that autoimmunity to the central nervous system (CNS) could explain these phenomena and undertook this study to determine whether peripheral inoculation with spinal cord homogenate on 1 or 2 occasions is associated with CNS-directed autoimmunity and neurodegeneration in a rat model.

METHODS

Rats were subcutaneously inoculated with saline or 75 mg of allogeneic spinal cord tissue on 1 or 2 occasions. Animals underwent Morris Water Maze testing, and serial serum samples were collected. Animals were sacrificed 8 weeks following the first inoculation. Autoantibody titers to myelin antigens MAG and GM1 were measured in serum. Immunohistochemistry was used to identify autoantibodies targeting NeuN-labeled neurons and CC1-labeled oligodendrocytes. Quantitative real-time polymerase chain reaction (qPCR) and western blotting were performed for pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 and the cell death marker caspase 3 as well as the neurodegenerative proteins tau and β-amyloid in both brain and spinal cord. Fluoro-Jade B was used to stain degenerating neurons, facilitating counting.

RESULTS

Animals inoculated with spinal cord homogenate exhibited increased titers of autoantibodies to MAG and GM1 and autoantibodies binding to neurons and oligodendrocytes. Double-inoculated animals demonstrated a significant increase in the expression of pro-inflammatory cytokines in the brain (TNF-α, p = 0.016; IL-6, p = 0.009) as well as the spinal cord (TNF-α, p = 0.024; IL-6, p = 0.002). The number of degenerating neurons was significantly increased in the brain and spinal cord of inoculated animals (p < 0.0001 and p = 0.028, respectively). Elevated expression of tau and β-amyloid was seen in brain of double-inoculated animals (p = 0.003 and p = 0.009, respectively). Inflammatory marker expression in the brain was positively correlated with anti-myelin autoimmune antibody titers and with tau expression in the brain. Inoculated animals showed impaired memory function in Morris Water Maze testing (p = 0.043).

CONCLUSIONS

The results of these experiments demonstrate that peripheral exposure to spinal cord antigens is associated with CNS-directed autoimmunity and inflammation in the brain and spinal cord as well as degeneration of CNS cells, memory impairment, and production of neurodegenerative proteins particularly when this exposure is repeated. These data support CNS autoimmunity as a candidate mechanism for the dementia that can follow SCI and perhaps other posttraumatic dementias such as chronic traumatic encephalopathy.

Influence of myeloperoxidase on colon tumor occurrence in inflamed versus non-inflamed colons of Apc(Min/+) mice

Control of colorectal cancer needs to be tailored to its etiology. Tumor promotion mechanisms in colitis-associated colon cancer differ somewhat from the mechanisms involved in hereditary and sporadic colorectal cancer. Unlike sporadic or inherited tumors, some experimental models show that colitis-associated colon tumors do not require cyclooxygenase (COX) expression for progression, and non-steroidal anti-inflammatory drugs (NSAIDs) which prevent sporadic or inherited colon cancer do not prevent colitis-associated colon cancer. We report that myeloperoxidase (MPO), an ancestor of the COX isoenzymes, is a determinant of colitis-associated colon tumors in Apc^Min/+ mice. During experimentally induced colitis, inhibition of MPO by resorcinol dampened colon tumor development. Conversely, in the bowels of Apc^Min/+ mice without colitis, resorcinol administration or ‘knockout’ of MPO gene coincided with a slight, but discernible increase in colon tumor incidence. Acrolein, a by-product of MPO catalysis, formed a covalent adduct with the phosphatase tensin homolog (PTEN) tumor suppressor and enhanced the activity of the Akt kinase proto-oncogene in vitro and in vivo. Thus, MPO may be an important determinant of diet and inflammation on colon cancer risk via its effect on endogenous exposure to oxidants and acrolein. We propose a hypothetical model to explain an apparent dichotomy between colon tumor occurrence and MPO inhibition in inflamed versus non-inflamed colons.

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Myeloperoxidase is a determinant of colitis-associated colon tumors in Apc^Min/+ mice.

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Inhibition of MPO by resorcinol dampened colitis-associated colon tumor occurrence. Acrolein is a by-product of MPO catalysis.

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Acrolein forms a covalent adduct with the phosphatase tensin homolog tumor suppressor.

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Acrolein adducted PTEN enhances the activity of the Akt kinase proto-oncogene.

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MPO may have an effect on endogenous exposure to oxidants and acrolein. MPO may be an important determinant of diet and inflammation on colon cancer risk.

Diacylglycerol kinase η modulates oncogenic properties of lung cancer cells

PURPOSE

Lung cancer is a leading cause of cancer deaths and efforts are underway to identify novel therapies to treat these tumors. Diacylglycerol kinase η (DGKη), an enzyme that phosphorylates diacylglycerol to form phosphatidic acid, has been shown to modulate MAPK signaling downstream of EGFR, which is an oncogenic driver in some lung cancers. Since mutations in EGFR and K-Ras are common in lung cancer, we hypothesized that limiting the function of DGKη would attenuate oncogenic properties of lung cancer cells.

METHODS

We determined the expression levels of DGKη in a mouse models of mutant EGFR and K-Ras lung cancer and in human lung cancer cell lines with activating mutations in either EGFR or K-Ras. We also tested the effects of shRNA-mediated depletion of DGKη in lung cancer cells and tested if DGKη depletion augmented the effects of afatinib, a new generation EGFR inhibitor.

RESULTS

DGKη was expressed in malignant epithelium from mice with mutant EGFR or K-Ras lung cancer. It was also expressed in human lung cancer cell lines with EGFR or K-Ras mutations. Depleting DGKη in lung cancer cell lines, harboring mutant EGFR, reduced their growth on plastic and in soft agar and also augmented the effects of afatinib, an EGFR inhibitor. DGKη depletion also reduced growth of one of two lung cancer cell lines that harbored mutant K-Ras.

CONCLUSIONS

Our data indicate that DGKη is a potential therapeutic target in lung cancers, especially those harboring EGFR mutations. Our findings warrant further studies to examine the effects of limiting its function in vivo.

Prenatal allergen exposures prevent allergen-induced sensitization and airway inflammation in young mice

BACKGROUND

Immune-modulation such as tolerance induction appears to be an upcoming concept to prevent development of atopic diseases. Pregnancy might present a critical period for preventing allergic sensitization of the progeny. We investigated the effect of maternal allergen exposures during pregnancy on allergen-induced sensitization and airway inflammation in the offspring in a murine model.

METHODS

BALB/c mice were exposed to aerosolized ovalbumin (OVA) three times per week from day 7 of pregnancy until delivery (day 0). Offspring were systemically sensitized by six intraperitoneal injections with OVA between postnatal days 21 and 35, prior to airway allergen challenges on days 48, 49, and 50. Analyses were performed on day 52. To examine long-lasting effects of maternal OVA exposures some offspring were sensitized between days 115 and 129; analyses took place on day 147.

RESULTS

Compared to maternal placebo exposures, maternal OVA exposures suppressed OVA-specific IgE serum levels and inhibited development of allergen-induced airway inflammation in the OVA-sensitized offspring on both days 52 and 147. This protective effect was associated with a shift from a predominant Th2 immune response toward a predominant production of the cytokines IFN-γ and IL-10. Further, maternal OVA exposures were associated with development of CD25(+) Foxp3(+) regulatory T cells (T(regs)) in the OVA-sensitized offspring. Depletion of T(regs) or neutralization of IL-10 prior to allergen sensitization re-established OVA-induced sensitization and eosinophilic airway inflammation in the OVA-sensitized offspring.

CONCLUSIONS

In our model, maternal allergen exposures during pregnancy prevented later allergen-mediated sensitization and airway inflammation by allergen-specific tolerance induction in the offspring.

[Nephropathia epidemica caused by Puumala hantavirus infection: a case report from the outpatient sector]

HISTORY AND ADMISSION FINDINGS

A 42-year-old man without pre-existing health problems presented to his family practitioner in Baden-Württemberg with fever (up to 39˚ C for two days), headache, abdominal pain, back pain and aching limbs. Ten days before, he had done heavy gardening work. He felt diffuse pain on abdominal palpation. The physical examination of the skin, lymph nodes, the heart, the lungs and the oral mucosa was unremarkable.

INVESTIGATIONS AND DIAGNOSIS

Erythrocytes, leukocytes and sporadic bacteria were found in the urine. Urine test strip analysis gave a threefold positive result for protein. The blood test revealed in an elevated C-reactive protein, leukocytosis, elevated creatinine and thrombocytopenia. Enlarged kidneys and an enlarged spleen were found on ultra sound examination. IgG and IgM tested for Hantavirus infection were detected by IFA (Immunofluorescence antibody assay) and by ELISA (enzyme-linked immunosorbent assay).

TREATMENT AND COURSE

The blood tests had returned to normal by 15 days after onset of the fever which had persisted for 7 days. Oliguria and/or anuria did not occur. After three weeks of illness, the blood pressure was found to be at hypertensive levels and the patient was treated with antihypertensive drugs.

CONCLUSION

A history of gardening work (exposure to rodents) and nonspecific symptoms (like headache and fever), in combination with elevated serum creatinine and thrombocytopenia, should raise the suspicion of nephropathia epidemica (hemorrhagic fever with renal syndrome) caused by hantavirus infection. As sequelae of hantavirus infection may persist, patients should subsequently be followed for clinical and laboratory evidence of renal disease. Hospitalization is not generally warranted.

Abstract 2274: Effect of myeloperoxidase inhibitor resorcinol on colon tumorigenesis in APCmin/+ mice

Beneficial actions of non-steroidal anti-inflammatory drugs (NSAIDs) on colorectal cancer progression are well accepted. Nevertheless, NSAIDs have had only a minor impact in primary or secondary prevention - even in high risk populations - for at least two reasons. First, NSAIDs are contra-indicated in some high risk conditions, such as colitis-associated colorectal cancer, because of their corrosive actions in the gut. Second, publicity about the cardiovascular safety of NSAIDs has thwarted their potential in primary or secondary prevention of sporadic polyps. Thus, we sought to identify molecular targets and agents that might work in these situations. Myeloperoxidase (MPOx) from neutrophils is distantly related to the cyclooxygenase (COX) enzymes. MPOx and its relative, eosinophil peroxidase (EPOx) constitute part of the innate immune process in the normal gut, and the pathology of colitis. Hypochlorite generated by MPOx oxidizes amino acids (serine, threonine) and polyunsaturated fatty acids (arachidonic acid). Several of these oxidative by-products generated by MPOx - hypochlorite are non-prostaglandin E2 (PGE2) mediators that enhance β-catenin signaling. Thus, we hypothesized that MPOx and its by-products may promote intestinal malignancy, comparable to the actions of COX and PGE2.

Using APCmin/+ mice we tested the effect of resorcinol, an irreversible MPOx inhibitor, under two experimental conditions: 1) colorectal and intestinal tumor promotion accompanying inflammation induced with dextran sodium sulfate (DSS); and 2) tumor formation in the normal intestine, without colitis, but with basal “inflammation” (para-inflamation) due to commensal bacteria in the gut. For APCmin/+ mice with DSS induced inflammation, 1.25mg/kg intraperitoneal (IP) resorcinol caused a 30% reduction in colorectal adenoma numbers, and a 40% reduction in average adenoma size (p&lt;0.05). Small intestinal polyp numbers were also reduced by 20%. Surprisingly, in APCmin/+ mice without DSS-induced colitis, but with basal “inflammation” of the normal gut, resorcinol 1.25mg/kg IP caused a modest, but detectable increase in adenoma formation. To reconcile these results we hypothesize that anti-inflammatory effects dominate the high intensity inflammation in the DSS colitis-APCmin/+ mouse, and manifest as reduced colitis-associated tumor formation. Conversely, we hypothesize that anti-inflammatory action in the lesser basal “inflammation” of normal APCmin/+ mice suppresses innate immune surveillance and elimination processes, which spares aberrant crypt foci. Alternatively, oxidation of resorcinol in the gut of normal APCmin/+ mice may be generating tumor promoting quinine metabolites. We are breeding an MPOx null-APCmin/+ mouse to help distinguish between these two alternatives.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2274.

Diacylglycerol kinase delta and protein kinase C(alpha) modulate epidermal growth factor receptor abundance and degradation through ubiquitin-specific protease 8

Many human epithelial cancers are characterized by abnormal activation of the epidermal growth factor receptor (EGFR), which is often caused by its excessive expression in tumor cells. The abundance of EGFR is modulated, in part, by its ubiquitination, which targets it for degradation. The components responsible for adding ubiquitin to EGFR are well characterized, but this is a reversible process, and the mechanisms that modulate the removal of ubiquitin from the EGFR are not well known. We found that de-ubiquitination of EGFR was regulated by diacylglycerol kinase delta (DGKdelta), a lipid kinase that terminates diacylglycerol signaling. In DGKdelta-deficient cells, ubiquitination of EGFR was enhanced, which attenuated the steady-state levels of EGFR and promoted its ligand-induced degradation. These effects were not caused by changes in the ubiquitinating apparatus, but instead were due to reduced expression of the de-ubiquitinase, ubiquitin-specific protease 8 (USP8). Depletion of protein kinase Calpha (PKCalpha), a target of diacylglycerol, rescued the levels of USP8 and normalized EGFR degradation in DGKdelta-deficient cells. Moreover, the effects of PKCalpha were caused by its inhibition of Akt, which stabilizes USP8. Our data indicate a novel mechanism where DGKdelta and PKCalpha modulate the levels of ubiquitinated EGFR through Akt and USP8.

Multiple enzyme activities of flavivirus proteins

Dengue viruses (DENV) have 5'-capped RNA genomes of (+) polarity and encode a single polyprotein precursor that is processed into mature viral proteins. NS2B, NS3 and NS5 proteins catalyse/activate enzyme activities that are required for key processes in the virus life cycle. The heterodimeric NS2B/NS3 is a serine protease required for processing. Using a high-throughput protease assay, we screened a small molecule chemical library and identified -200 compounds having > or = 50% inhibition. Moreover, NS3 exhibits RNA-stimulated NTPase, RNA helicase and the 5'-RNA triphosphatase activities. The NTPase and the 5'-RTPase activities of NS3 are stimulated by interaction with NS5. Moreover, the conserved, positively charged motif in DENV-2 NS3, 184RKRK, is required for RNA binding and modulates the RNA-dependent enzyme activities of NS3. To study viral replication, a variety of methods are used such as the in vitro RNA-dependent RNA polymerase assays that utilize lysates from DENV-2-infected mosquito or mammalian cells or the purified NS5 along with exogenous short subgenomic viral RNAs or the replicative intracellular membrane-bound viral RNAs as templates. In addition, a cell-based DENV-2 replicon RNA encoding a luciferase reporter is also used to examine the role of cis-acting elements within the 3' UTR and the RKRK motif in viral replication.

Helicity amplitudes A1/2 and A3/2 for the D13(1520) resonance obtained from the gamma-->p-->-->ppi(0) Reaction

The helicity dependence of the gamma-->p-->-->ppi(0) reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.

International conferences on violence against women

Violence against women has been written about as an international health issue. Since 1975 international conferences and organizations have addressed the problems. The resulting resolutions requested that measures be taken to eliminate violence against women.

Results of the single-radial-diffusion test with formaldehyde-treated influenza virus

We found reduced values for formaldehyde-treated influenza virus in the single-radial-diffusion test by comparison with non-treated virus. The reduction correlates with the formaldehyde concentration. Hemagglutination and neuraminidase activities were not affected by the same treatment. We therefore suggest that this reduction is not based on antigen destruction.

Freeze-drying of a purified human diploid cell rabies vaccine

A rabies vaccine prepared in human diploid cell strains was purified by continuous-flow sucrose density gradient centrifugation. The peak fractions containing 35-40% sucrose were diluted with a stabilizer consisting of degraded gelatine in a Tris-EDTA-buffer, and then inactivated with beta-propiolactone and freeze-dried to a residual moisture of approximately 2.5%. This vaccine was stable as proved by accelerated stability tests.