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result(s) for
"Downes, M. R"
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A pilot ‘window of opportunity’ neoadjuvant study of metformin in localised prostate cancer
Background:
Metformin is an inhibitor of complex 1 in the respiratory chain, and is widely used to reduce insulin resistance. It has also been described to have pleotropic effects including via AMPK on inhibiting the mTOR kinase. Pre-clinical and epidemiological studies suggest an ability to modulate disease evolution in prostate cancer. In this study, we aimed to (i) demonstrate safety and tolerability of neoadjuvant metformin administration and (ii) document changes in proliferative (Ki67) and AMPK-related signalling indices between matching biopsies and prostatectomies
Methods:
Men were treated in a single-arm ‘window of opportunity’ study between their decision to undergo radical prostatectomy and the operation itself. Forty patients were planned but only 24 patients were enrolled owing to slow accrual. Twenty-one patients were evaluable for pathological outcomes and 22 for serum metabolic indices. Metformin was given at doses to 500 mg t.i.d. Ki67 index was calculated using the Aperio-positive pixel count algorithm, whereas immunohistochemical measurements were by consensus H-Score. Comparative statistics were analysed by students
t
-tests and/or Wilcoxon matched pairs signed rank test.
Results:
Baseline characteristics included median PSA 6 ng ml
−1
(3.22–36.11 ng ml
−1
). Median duration of drug treatment was 41 days (18–81). Treatment was well tolerated with only three patients developing G3/4 toxicities. In a per patient and per tumour analyses, metformin reduced the Ki67 index by relative amounts of 29.5 and 28.6 % (
P
=0.0064 and
P
=0.0042) respectively. There was also a significant decrease in P-4EBP1 staining (
P
<0.001) but no change in P-AMPK or P-ACC. There were no correlations between any metabolic, morphometric or cancer-related serum indices. There was a trend towards PSA reduction (
P
=0.08). The study is limited by small patient numbers and tumour heterogeneity.
Conclusions:
Neoadjuvant metformin is well tolerated prior to radical prostatectomy. Data to date indicate promising effects on metabolic and tissue proliferation and signalling parameters.
Journal Article
Tiv Hairdressing: A Change in Custom. (With two text figures)
by
Bohannan, P J
,
Downes, R M
1956
Journal Article
Retinal gene therapy in patients with choroideremia: initial findings from a phase 1/2 clinical trial
by
Webster, Andrew R
,
Seabra, Miguel C
,
Tolmachova, Tanya
in
Adaptor Proteins, Signal Transducing - administration & dosage
,
Adaptor Proteins, Signal Transducing - genetics
,
Adeno-associated virus
2014
Choroideremia is an X-linked recessive disease that leads to blindness due to mutations in the CHM gene, which encodes the Rab escort protein 1 (REP1). We assessed the effects of retinal gene therapy with an adeno-associated viral (AAV) vector encoding REP1 (AAV.REP1) in patients with this disease.
In a multicentre clinical trial, six male patients (aged 35–63 years) with choroideremia were administered AAV.REP1 (0·6–1·0×1010 genome particles, subfoveal injection). Visual function tests included best corrected visual acuity, microperimetry, and retinal sensitivity tests for comparison of baseline values with 6 months after surgery. This study is registered with ClinicalTrials.gov, number NCT01461213.
Despite undergoing retinal detachment, which normally reduces vision, two patients with advanced choroideremia who had low baseline best corrected visual acuity gained 21 letters and 11 letters (more than two and four lines of vision). Four other patients with near normal best corrected visual acuity at baseline recovered to within one to three letters. Mean gain in visual acuity overall was 3·8 letters (SE 4·1). Maximal sensitivity measured with dark-adapted microperimetry increased in the treated eyes from 23·0 dB (SE 1·1) at baseline to 25·3 dB (1·3) after treatment (increase 2·3 dB [95% CI 0·8–3·8]). In all patients, over the 6 months, the increase in retinal sensitivity in the treated eyes (mean 1·7 [SE 1·0]) was correlated with the vector dose administered per mm2 of surviving retina (r=0·82, p=0·04). By contrast, small non-significant reductions (p>0·05) were noted in the control eyes in both maximal sensitivity (–0·8 dB [1·5]) and mean sensitivity (–1·6 dB [0·9]). One patient in whom the vector was not administered to the fovea re-established variable eccentric fixation that included the ectopic island of surviving retinal pigment epithelium that had been exposed to vector.
The initial results of this retinal gene therapy trial are consistent with improved rod and cone function that overcome any negative effects of retinal detachment. These findings lend support to further assessment of gene therapy in the treatment of choroideremia and other diseases, such as age-related macular degeneration, for which intervention should ideally be applied before the onset of retinal thinning.
UK Department of Health and Wellcome Trust.
Journal Article
Identification of LZTFL1 as a candidate effector gene at a COVID-19 risk locus
2021
The severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) disease (COVID-19) pandemic has caused millions of deaths worldwide. Genome-wide association studies identified the 3p21.31 region as conferring a twofold increased risk of respiratory failure. Here, using a combined multiomics and machine learning approach, we identify the gain-of-function risk A allele of an SNP, rs17713054G>A, as a probable causative variant. We show with chromosome conformation capture and gene-expression analysis that the rs17713054-affected enhancer upregulates the interacting gene, leucine zipper transcription factor like 1 (
LZTFL1
). Selective spatial transcriptomic analysis of lung biopsies from patients with COVID-19 shows the presence of signals associated with epithelial–mesenchymal transition (EMT), a viral response pathway that is regulated by
LZTFL1
. We conclude that pulmonary epithelial cells undergoing EMT, rather than immune cells, are likely responsible for the 3p21.31-associated risk. Since the 3p21.31 effect is conferred by a gain-of-function,
LZTFL1
may represent a therapeutic target.
SNP rs17713054 in the 3p21.31 COVID-19 risk locus is identified as a probable causative variant for disease association. Chromatin conformation and gene expression data indicate that
LZTFL1
is impacted by rs17713054 in pulmonary epithelial cells.
Journal Article
Suppression of cellular proliferation and invasion by the concerted lipid and protein phosphatase activities of PTEN
by
Glancy, B
,
Maccario, H
,
Leslie, N R
in
Apoptosis
,
Biological and medical sciences
,
Cell Biology
2010
PTEN is a tumour suppressor with phosphatase activity
in vitro
against both lipids and proteins and other potential non-enzymatic mechanisms of action. Although the importance of PTEN's lipid phosphatase activity in regulating the PI3K signalling pathway is recognized, the significance of PTEN's other mechanisms of action is currently unclear. In this study, we describe the systematic identification of a PTEN mutant, PTEN Y138L, with activity against lipid, but not soluble substrates. Using this mutant, we provide evidence for the interfacial activation of PTEN against lipid substrates. We also show that when re-expressed at physiological levels in PTEN null U87MG glioblastoma cells, the protein phosphatase activity of PTEN is not required to regulate cellular PtdInsP
3
levels or the downstream protein kinase Akt/PKB. Finally, in three-dimensional Matrigel cultures of U87MG cells similarly re-expressing PTEN mutants, both the protein and lipid phosphatase activities were required to inhibit invasion, but either activity alone significantly inhibited proliferation, albeit only weakly for the protein phosphatase activity. Our data provide a novel tool to address the significance of PTEN's separable lipid and protein phosphatase activities and suggest that both activities suppress proliferation and together suppress invasion.
Journal Article
Change Points in the Population Trends of Aerial-Insectivorous Birds in North America: Synchronized in Time across Species and Regions
by
Smith, Adam C.
,
Downes, Constance M.
,
Francis, Charles M.
in
Animal breeding
,
Animals
,
Bayesian analysis
2015
North American populations of aerial insectivorous birds are in steep decline. Aerial insectivores (AI) are a group of bird species that feed almost exclusively on insects in flight, and include swallows, swifts, nightjars, and flycatchers. The causes of the declines are not well understood. Indeed, it is not clear when the declines began, or whether the declines are shared across all species in the group (e.g., caused by changes in flying insect populations) or specific to each species (e.g., caused by changes in species' breeding habitat). A recent study suggested that population trends of aerial insectivores changed for the worse in the 1980s. If there was such a change point in trends of the group, understanding its timing and geographic pattern could help identify potential causes of the decline. We used a hierarchical Bayesian, penalized regression spline, change point model to estimate group-level change points in the trends of 22 species of AI, across 153 geographic strata of North America. We found evidence for group-level change points in 85% of the strata. Change points for flycatchers (FC) were distinct from those for swallows, swifts and nightjars (SSN) across North America, except in the Northeast, where all AI shared the same group-level change points. During the 1980s, there was a negative change point across most of North America, in the trends of SSN. For FC, the group-level change points were more geographically variable, and in many regions there were two: a positive change point followed by a negative change point. This group-level synchrony in AI population trends is likely evidence of a response to a common environmental factor(s) with similar effects on many species across broad spatial extents. The timing and geographic patterns of the change points that we identify here should provide a spring-board for research into the causes behind aerial insectivore declines.
Journal Article