Biological Features of Human Papillomavirus-related Head and Neck Cancers Contributing to Improved Response

Head and neck squamous cell carcinomas (HNSCC) are the sixth most common malignancy globally, and an increasing proportion of oropharyngeal HNSCCs are associated with the human papillomavirus (HPV). Patients with HPV-associated tumours have markedly improved overall and disease-specific survival compared with their HPV-negative counterparts when treated with chemoradiation. Although the difference in outcomes between these two groups is clearly established, the mechanism underlying these differences remains an area of investigation. Data from preclinical, clinical and genomics studies have started to suggest that an increase in radio-sensitivity of HPV-positive HNSCC may be responsible for improved outcomes, the putative mechanisms of which we will review here. The Cancer Genome Atlas and others have recently documented a multitude of molecular differences between HPV-positive and HPV-negative tumours. Preclinical investigations by multiple groups have explored possible mechanisms of increased sensitivity to therapy, including examining differences in DNA repair, hypoxia and the immune response. In addition to differences in the response to therapy, some groups have started to investigate phenotypic differences between the two diseases, such as tumour invasiveness. Finally, we will conclude with a brief review of ongoing clinical trials that are attempting to de-escalate treatment to minimise long-term toxicity while maintaining cure rates. New insights from preclinical and genomic studies may eventually lead to personalised treatment paradigms for HPV-positive patients.

Antidepressive-like effects of rapamycin in animal models: Implications for mTOR inhibition as a new target for treatment of affective disorders

Lithium, the prototypic mood stabilizer, was recently demonstrated to enhance autophagy in cells. Recent hypotheses regarding the source of therapeutic effects of lithium as well as other mood stabilizers and antidepressants suggest that they may stem from increased neuroprotection, cellular plasticity and resilience. Hence it is clearly a possibility that enhanced autophagy may be involved in the therapeutic action by contributing to increased cellular resilience. A well-documented mechanism to induce autophagy is by inhibition of mTOR, a negative modulator of autophagy and rapamycin (sirolimus) is a commonly used inhibitor of mTOR. Accordingly, the present study was designed to evaluate the effects of rapamycin in animal models of antidepressant activity. A dose-response experiment in the mice forced swim test was performed and followed by additional testing of mice and rats in an open field, the forced swim test and the tail suspension test. Results show that sub-chronic, but not acute, administration of rapamycin doses of 10mg/kg and above, have an antidepressant-like effect in both mice and rats and in both the forced swim and the tail suspension tests with no effects on the amount or distribution of activity in the open field. Whereas it is tempting to conclude that the antidepressant-like effects are related to mTOR inhibition, they may also be the consequences of interactions with other intracellular pathways. Additional studies are now planned to further explore the behavioral range of rapamycin's effects as well as the biological mechanisms underlying these effects.

Enhanced endothelium derived hyperpolarising factor activity in resistance arteries from normal pressure glaucoma patients: implications for vascular function in the eye

BACKGROUND/AIMS

Endothelial cell dysfunction in the ocular circulation may contribute to normal pressure glaucoma (NPG). This study aimed to investigate the contributions made by endothelium derived relaxing factors to relaxation of (1) subcutaneous resistance arteries from patients with NPG, and (2) porcine ciliary arteries.

METHODS

Human gluteal resistance arteries were isolated from seven patients with NPG and matched controls. Human and porcine arteries produced endothelium dependent relaxation when exposed to acetylcholine (ACh) (10(-9)-3 x 10(-5)M) or bradykinin (10(-10)-3 x 10(-6)M). Pharmacological agents were used to inhibit the nitric oxide pathway (l-arginine analogues, soluble guanylate cyclase inhibitor), endothelium derived hyperpolarising factor (EDHF) activity (potassium channel antagonists), and prostaglandin synthesis (cyclo-oxygenase inhibitors).

RESULTS

In all arteries, endothelium dependent relaxation was attenuated by nitric oxide (NO) inhibition or potassium channel blockade, but not by cyclo-oxygenase inhibition. Inhibition of ACh mediated relaxation by potassium channel antagonists was greater (p<0.05) in patients with NPG (Emax, 55.4% (SD 8.16%) relaxation, n = 4) than controls (Emax, 81.8% (6.0%), n = 5). In contrast, combined inhibition of NO synthase (NOS) and cyclo-oxygenase produced similar inhibition of ACh mediated relaxation in both groups.

CONCLUSIONS

The enhanced contribution of EDHF to ACh mediated relaxation in systemic resistance arteries from NPG patients may contribute to the maintained endothelium mediated relaxation in these vessels. EDHF also contributes significantly to bradykinin mediated relaxation in porcine ocular ciliary arteries. Therefore, similar changes in the balance of relaxing factors in the ocular circulation could influence the response of the eye to vascular endothelial dysfunction in NPG.

Population structure in the freshwater shrimp (Paratya australiensis) inferred from allozymes and mitochondrial DNA

In 1995, an allozyme study was conducted on the genetic structure of a population of the common atyid shrimp, Paratya australiensis, in the Conondale Range, south-eastern Queensland with two subcatchments each within two river drainages sampled. The allozyme study revealed a high degree of population structure, with the data interpreted as reflecting a pattern of restricted contemporary gene flow, primarily between streams within subcatchments. High levels of differentiation occurred between all subcatchments. In this study, we analysed a partial fragment of the mitochondrial COI gene in order to further test and verify these results. The mtDNA data largely conflicted with the hypothesis of restricted gene flow indicating that contemporary dispersal was highly unlikely, even between streams within subcatchments, with many sites fixed for unique mtDNA haplotypes. Additionally, the level of divergence between the Stony Creek subcatchment and all other sampling sites indicated that it had been isolated for approximately 2-3 million years, while low levels of divergence were detected across the Conondale Range between the Kilcoy and Booloumba Creek subcatchments. The sharing of alleles at certain allozyme loci between all subcatchments is, therefore, likely to be the result of ancestral retention and possibly because of the effects of balancing selection.

A hierarchical analysis of the genetic structure of an aquatic insect Bungona (Baetidae: Ephemeroptera)

Recent studies of the genetic structure of stream-dwelling organisms have suggested that fine-scale patterns are the consequence of patchy recruitment from a small number of matings and limited in-stream dispersal. Predictions of this hypothesis were tested by spatial and temporal analysis of the genetic structure of populations of a stream mayfly (Bungona sp: Baetidae) in subtropical streams in south-eastern Queensland. Significant departures from Hardy-Weinberg proportions occurred more often than would be predicted by chance alone and no consistent pattern was observed across sites, loci or sampling times. As in previous studies, the largest differentiation was observed at the smallest spatial scale (reaches within streams) on most sampling occasions. These data provide additional support for a patchy recruitment hypothesis. Despite the fine-scale population structure, there was evidence of widespread adult dispersal across the study region, especially between streams and subcatchments within the same block of continuous dense forest.

Drug treatment of functional dyspepsia: a systematic analysis of trial methodology with recommendations for design of future trials

OBJECTIVES

To evaluate drug treatment of functional dyspepsia (including Helicobacter pylori) and provide guidelines for future trials based on a critical systematic overview of published studies.

METHODS

Data sources were a Medline search for articles published in English going back to 1966 and a manual search of four GI journals going back to 1980. Original randomized, double-blind, placebo-controlled trials were selected that enrolled at least 20 patients. Using a standardized, pretested data extraction form, studies were evaluated independently by two observers for study design, outcome measures, and results.

RESULTS

Fifty two eligible studies were evaluated. Many studies suffered from important weaknesses in study design and execution. Only five studies used previously validated outcome measures.

CONCLUSIONS

Because of suboptimal design and/or unclear presentation of the data, none of the trials provided unequivocal evidence that there is efficacious therapy for the treatment of functional dyspepsia.

Transperineurial arterioles in human sural nerve

The perineurial sheath of nerve fascicles is a protective cellular layer that separates the endoneurium from the epineurium. Transperineurial arterioles (TPA) connect the endoneurial capillary plexuses to the epineurial arterial nutrient supply. Transperineurial arterioles are defined as any arteriole that is confined to a perineurial cell compartment, which would include all arterioles within the perineurium proper or within perineurial sleeves in the epi- or endoneurium. In this study of biopsied human sural nerves, three-dimensional reconstruction of one micron sections and ultrastructural analysis of step serials, we find that TPA are confined in open-ended perineurial sleeves by which they pass from the epineurium through the perineurial sheath proper into the endoneurium. Most TPA are terminal arterioles as evidenced by size (10-25 microns), morphological characteristics, and the fact that they connect with capillaries. Transperineurial arterioles gradually lose their continuous muscle coat and become post-arteriolar capillaries (PAC). Vascular segments that emerge into the endoneurium from the perineurial sleeves are generally of the PAC variety. Transperineurial arterioles and post-arteriolar capillaries are often associated with a plexus of unmyelinated nerve fibers. Axon varicosities exhibit a variety of morphologically distinct vesicles including dense-cored and a diversity of agranular vesicles. These findings suggest that TPA play a role in the neurogenic control of endoneurial blood flow.