154 research outputs found
C-Peptide Prevents Hippocampal Apoptosis in Type 1 Diabetes
To explore mechanisms underlying central nervous system
(CNS) complications in diabetes, we examined hippocampal neuronal
apoptosis and loss, and the effect of C-peptide replacement
in type 1 diabetic BB/W rats. Apoptosis was demonstrated after
8 months of diabetes, by DNA fragmentation, increased number of
apoptotic cells, and an elevated ratio of Bax/Bcl-xL, accompanied
by reduced neuronal density in the hippocampus. No apoptotic activity
was detected and neuronal density was unchanged in 2-month
diabetic hippocampus, whereas insulin-like growth factor (IGF) activities
were impaired. In type 1 diabetic BB/W rats replaced with
C-peptide, no TdT-mediated dUTP nick-end labeling (TUNEL)-
positive cells were shown and DNA laddering was not evident in
hippocampus at either 2 or 8 months. C-peptide administration prevented
the preceding perturbation of IGF expression and reduced
the elevated ratio of Bax/Bcl-xL. Our data suggest that type 1 diabetes
causes a duration-dependent programmed cell death of the
hippocampus, which is partially prevented by C-peptide
The Insulin-Like Growth Factor System and Neurological Complications in Diabetes
The IGF system plays vital roles in neuronal development,
metabolism, regeneration and survival. It consists of
IGF-I, IGF-II, insulin, IGF-I-receptor, and those of IGF-II
and insulin as well as IGF-binding proteins. In the last
decades it has become clear that perturbations of the IGF
system play important roles in the pathogenesis of diabetic
neurological complications. In the peripheral nervous system
IGF-I, insulin, and C-peptide particularly in type 1 diabetes
participate in the development of axonal degenerative
changes and contributes to impaired regenerative capacities.
These abnormalities of the IGF system appear to be
less pronounced in type 2 diabetes, which may in part account
for the relatively milder neurological complications
in this type of diabetes. The members of the IGF system
also provide anti-apoptotic effects on both peripheral and
central nervous system neurons. Furthermore, both insulin
and C-peptide and probably IGF-I possess gene regulatory
capacities on myelin constituents and axonal cytoskeletal
proteins. Therefore, replenishment of various members of
the IGF system provides a reasonable rational for prevention
and treatment of diabetic neurological complications
The Effects of C-peptide on Type 1 Diabetic Polyneuropathies and Encephalopathy in the BB/Wor-rat
Diabetic polyneuropathy (DPN) occurs more frequently in type 1 diabetes resulting in a more severe DPN. The differences in DPN between the two types of diabetes are due to differences in the availability of insulin and C-peptide. Insulin and C-peptide provide gene regulatory effects on neurotrophic factors with effects on axonal cytoskeletal proteins and nerve fiber integrity. A significant abnormality in type 1 DPN is nodal degeneration. In the type 1 BB/Wor-rat, C-peptide replacement corrects metabolic abnormalities ameliorating the acute nerve conduction defect. It corrects abnormalities of neurotrophic factors and the expression of neuroskeletal proteins with improvements of axonal size and function. C-peptide corrects the expression of nodal adhesive molecules with prevention and repair of the functionally significant nodal degeneration.
Cognitive dysfunction is a recognized complication of type 1 diabetes, and is associated with impaired neurotrophic support and apoptotic neuronal loss. C-peptide prevents hippocampal apoptosis and cognitive deficits. It is therefore clear that substitution of C-peptide in type 1 diabetes has a multitude of effects on DPN and cognitive dysfunction.
Here the effects of C-peptide replenishment will be extensively described as they pertain to DPN and diabetic encephalopathy, underpinning its beneficial effects on neurological complications in type 1 diabetes
C-peptide and Retinal Microangiopathy in Diabetes
Increased extracellular matrix (ECM) protein deposition
and capillary basement membrane (BM) thickening are
characteristic features of diabetic retinal microangiopathy.
Recent observations in the authors' laboratories suggest
that high glucose in endothelial cells as well as diabetes
causes up-regulation of total fibronectin (FN), as well as
extradomain-B (EDB) containing the spliced variant of FN,
oncofetal FN, in the retina. This splice variant is normally
absent in mature adult tissues and is believed to be involved
in angiogenesis. In this study, the authors have investigated
the role of C-peptide in the production of ECM
proteins and capillary BM thickening in the retina of diabetic
rats. They investigated retinas from poorly controlled
diabetic BB/Wor rats with or without C-peptide treatment
as well as those from age-matched nondiabetic control rats
after 8 months of diabetes. In addition, the authors investigated
retinas from BBDRZ/Wor rats, a model of type 2
diabetes. Following a treatment period of 8 months, retinal
tissues were harvested for gene expression and histological
analyses. In the retinas of diabetic BB/Wor rats, a
significant increase of oncofetal FN was demonstrated compared
to control rats. C-peptide treatment of BB/Wor rats
completely prevented such increase. Furthermore, retinas
from BBDRZ/Wor rats, did not exhibit any such alteration
in oncofetal FN expression. The authors further examined retinal capillary BM thickening using ultrastructural
morphometry. C-peptide treatment was ineffective in preventing
the diabetes-induced increase in capillary BM thickness.
The authors' previous studies of cultured endothelial
cells demonstrated that oncofetal FN synthesis is, at
least in part, mediated via transforming growth factor-β
(TGF-β) and endothelin-1 (ET-1). Hence, they examined
these two transcripts in the retina of these animals. Diabetes
caused significant increase in mRNA expression of ET-1 and
TGF-β, which was not prevented by C-peptide treatment.
Hence it appears that C-peptide is effective in preventing
diabetes-induced oncofetal FN expression and that these effects
are not mediated via ET-1 or TGF-β. In conclusion,
these data suggest that C-peptide is involved in regulating
ECM protein composition. Furthermore, normalization of
diabetes-induced oncofetal FN up-regulation may suggest
importance of C-peptide in advanced alterations in diabetic
retinopathy such as angiogenesis
ViT-Lens: Towards Omni-modal Representations
Though the success of CLIP-based training recipes in vision-language models,
their scalability to more modalities (e.g., 3D, audio, etc.) is limited to
large-scale data, which is expensive or even inapplicable for rare modalities.
In this paper, we present ViT-Lens that facilitates efficient omni-modal
representation learning by perceiving novel modalities with a pretrained ViT
and aligning to a pre-defined space. Specifically, the modality-specific lens
is tuned to project multimodal signals to the shared embedding space, which are
then processed by a strong ViT that carries pre-trained image knowledge. The
encoded multimodal representations are optimized toward aligning with the
modal-independent space, pre-defined by off-the-shelf foundation models. A
well-trained lens with a ViT backbone has the potential to serve as one of
these foundation models, supervising the learning of subsequent modalities.
ViT-Lens provides a unified solution for representation learning of increasing
modalities with two appealing benefits: (i) Exploiting the pretrained ViT
across tasks and domains effectively with efficient data regime; (ii) Emergent
downstream capabilities of novel modalities are demonstrated due to the
modality alignment space. We evaluate ViT-Lens in the context of 3D as an
initial verification. In zero-shot 3D classification, ViT-Lens achieves
substantial improvements over previous state-of-the-art, showing 52.0% accuracy
on Objaverse-LVIS, 87.4% on ModelNet40, and 60.6% on ScanObjectNN. Furthermore,
we enable zero-shot 3D question-answering by simply integrating the trained 3D
lens into the InstructBLIP model without any adaptation. We will release the
results of ViT-Lens on more modalities in the near future.Comment: 19 pages, 4 figures and 9 table
Too Large; Data Reduction for Vision-Language Pre-Training
This paper examines the problems of severe image-text misalignment and high
redundancy in the widely-used large-scale Vision-Language Pre-Training (VLP)
datasets. To address these issues, we propose an efficient and straightforward
Vision-Language learning algorithm called TL;DR, which aims to compress the
existing large VLP data into a small, high-quality set. Our approach consists
of two major steps. First, a codebook-based encoder-decoder captioner is
developed to select representative samples. Second, a new caption is generated
to complement the original captions for selected samples, mitigating the
text-image misalignment problem while maintaining uniqueness. As the result,
TL;DR enables us to reduce the large dataset into a small set of high-quality
data, which can serve as an alternative pre-training dataset. This algorithm
significantly speeds up the time-consuming pretraining process. Specifically,
TL;DR can compress the mainstream VLP datasets at a high ratio, e.g., reduce
well-cleaned CC3M dataset from 2.82M to 0.67M (24\%) and noisy YFCC15M
from 15M to 2.5M (16.7\%). Extensive experiments with three popular VLP
models over seven downstream tasks show that VLP model trained on the
compressed dataset provided by TL;DR can perform similar or even better results
compared with training on the full-scale dataset. The code will be made
available at \url{https://github.com/showlab/data-centric.vlp}.Comment: Work in progress. Code: https://github.com/showlab/data-centric.vl
C-peptide reverses nociceptive neuropathy in type 1 diabetes
Autorzy zbadali działanie terapeutyczne peptydu C
w ustalonej neuropatii nocyceptywnej u szczurów
BB/Wor z cukrzycą typu 1. Oceniono nocyceptywną
funkcję nerwów, morfometrię niezmielinizowanych
włókien nerwu łydkowego i zwoju korzenia grzbietowego
(DRG), zawartość peptydu nocyceptywnego
oraz ekspresję czynników neurotroficznych i ich
receptorów. Peptyd C podawano w dawce substytucyjnej
drogą pompy osmotycznej w ciągłym wlewie
lub raz dziennie w iniekcji podskórnej. Szczury
z cukrzycą leczono od 4.-7. miesiąca trwania cukrzycy
i porównywano z nieleczonymi szczurami z grupy
kontrolnej w tym samym okresie choroby. Peptyd C
podawany przez pompę osmotyczną, lecz nie w iniekcjach
podskórnych, zmniejszył hiperalgezję i cukrzycozależną
redukcję liczby włókien niezmielinizowanych
(p < 0,01) oraz średnią wielkość aksonów
(p < 0,05) w nerwie łydkowym. Ekspresja receptora
czynnika wzrostu nerwu (NGF) o dużym podobieństwie
(NGFR-TrkA) w DRG zmniejszyła się znamiennie
w 4. miesiącu (p < 0,01). Ekspresja receptorów
insulinowego oraz IGF-1 w DGR i NFG w nerwie kulszowym zmniejszyła się znamiennie w 7. miesiącu
u szczurów z cukrzycą (odpowiednio: p < 0,01,
p < 0,05 i p < 0,005). Podawanie przez pompę osmotyczną
zapobiegło spadkowi ekspresji NGFR-TrkA,
receptora insulinowego (p < 0,05) i IGF-IR (p < 0,005)
w DRG oraz zwiększyło zawartość NGF (p < 0,05)
w nerwie kulszowym. Natomiast peptyd C podawany
drogą podskórną wpłynął jedynie w niewielkim
stopniu na morfometryczne i molekularne zmiany
u szczurów z cukrzycą. Stwierdzono, że peptyd C korzystnie
wpływa na cukrzycową neuropatię nocyceptywną;
aby uzyskać efekt optymalny, należy utrzymywać
fizjologiczne stężenie peptydu C w ciągu dnia.We examined the therapeutic effects of C-peptide
on established nociceptive neuropathy in type 1 diabetic
BB/Worrats. Nociceptive nerve function, unmyelinated
sural nerve fiber and dorsal root ganglion
(DRG) cell morphometry, nociceptive peptide content,
and the expression of neurotrophic factors and
their receptors were investigated. C-peptide was
administered either as a continuous subcutaneous
replacement dose via osmopumps or a replacement
dose given once daily by subcutaneous injection.
Diabetic rats were treated from 4 to 7 months of
diabetes and were compared with control and untreated
diabetic rats of 4- and 7-month duration. Osmopump
delivery but not subcutaneous injection improved hyperalgesia and restored the diabetesinduced
reduction of unmyelinated fiber number
(p < 0.01) and mean axonal size (p < 0.05) in the
sural nerve. High-affinity nerve growth factor (NGF)
receptor (NGFR-TrkA) expression in DRGs was significantly
reduced at 4 months (p < 0.01). Insulin receptor
and IGF-I receptor (IGF-IR) expressions in DRGs
and NGF content in sciatic nerve were significantly
decreased in 7-month diabetic rats (p < 0.01, 0.05,
and 0.005, respectively). Osmopump delivery prevented
the decline of NGFR-TrkA, insulin receptor
(p < 0.05), and IGF-IR (p < 0.005) expressions in DRGs
and improved NGF content (p < 0.05) in sciatic nerve.
However, subcutaneous injection had only marginal
effects on morphometric and molecular changes
in diabetic rats. We conclude that C-peptide
exerts beneficial therapeutic effects on diabetic
nociceptive neuropathy and that optimal effects
require maintenance of physiological C-peptide
concentrations for a major proportion of the day
Learning to Learn: How to Continuously Teach Humans and Machines
Our education system comprises a series of curricula. For example, when we
learn mathematics at school, we learn in order from addition, to
multiplication, and later to integration. Delineating a curriculum for teaching
either a human or a machine shares the underlying goal of maximizing the
positive knowledge transfer from early to later tasks and minimizing forgetting
of the early tasks. Here, we exhaustively surveyed the effect of curricula on
existing continual learning algorithms in the class-incremental setting, where
algorithms must learn classes one at a time from a continuous stream of data.
We observed that across a breadth of possible class orders (curricula),
curricula influence the retention of information and that this effect is not
just a product of stochasticity. Further, as a primary effort toward automated
curriculum design, we proposed a method capable of designing and ranking
effective curricula based on inter-class feature similarities. We compared the
predicted curricula against empirically determined effectual curricula and
observed significant overlaps between the two. To support the study of a
curriculum designer, we conducted a series of human psychophysics experiments
and contributed a new Continual Learning benchmark in object recognition. We
assessed the degree of agreement in effective curricula between humans and
machines. Surprisingly, our curriculum designer successfully predicts an
optimal set of curricula that is effective for human learning. There are many
considerations in curriculum design, such as timely student feedback and
learning with multiple modalities. Our study is the first attempt to set a
standard framework for the community to tackle the problem of teaching humans
and machines to learn to learn continuously
Effects of nitrate on the treatment of lead contaminated groundwater by nanoscale zerovalent iron
Nanoscale zerovalent iron (nZVI) is efficient for removing Pb(2+) and nitrate from water. However, the influence of nitrate, a common groundwater anion, on Pb(2+) removal by nZVI is not well understood. In this study, we showed that under excess Fe(0) conditions (molar ratio of Fe(0)/nitrate>4), Pb(2+) ions were immobilized more quickly (<5 min) than in nitrate-free systems (∼ 15 min) due to increasing pH. With nitrate in excess (molar ratio of Fe(0)/nitrate<4), nitrate stimulated the formation of crystal PbxFe3-xO4 (ferrite), which provided additional Pb(2+) removal. However, ∼ 7% of immobilized Pb(2+) ions were released into aqueous phase within 2h due to ferrite deformation. Oxidation-reduction potential (ORP) values below -600 mV correlated with excess Fe(0) conditions (complete Pb(2+) immobilization), while ORP values ≥-475 mV characterized excess nitrate conditions (ferrite process and Pb(2+) release occurrence). This study indicates that ORP monitoring is important for proper management of nZVI-based remediation in the subsurface to avoid lead remobilization in the presence of nitrate
The role of upfront primary tumor resection in asymptomatic patients with unresectable stage IV colorectal cancer: A systematic review and meta-analysis
BackgroundControversy exists over the role of upfront primary tumor resection (PTR) in asymptomatic patients with unresectable stage IV colorectal cancer (CRC). The purpose of this study was to evaluate the effect of upfront PTR on survival outcomes and adverse outcomes.MethodsSearches were conducted on PubMed, EMBASE, Web of Science, and Cochrane Library from inception to August 2021. Studies comparing survival outcomes with or without adverse outcomes between PTR and non-PTR treatments were included. Review Manager 5.3 was applied for meta-analyses with a random-effects model whenever possible.ResultsOverall, 20 studies with 3,088 patients were finally included in this systematic review. Compared with non-PTR, upfront PTR was associated with better 3-year (HR: 0.69, 95% CI, 0.57–0.83, P = 0.0001) and 5-year overall survival (OS) (HR: 0.77, 95% CI, 0.62–0.95, P = 0.01), while subgroup analysis indicated that there was no significant difference between upfront PTR and upfront chemotherapy (CT) group. In addition, grade 3 or higher adverse effects due to CT were more frequent in the PTR group with marginal significance (OR: 1.74, 95% CI, 0.99–3.06, P = 0.05), and other adverse outcomes were comparable.ConclusionsPTR might be related to improved OS for asymptomatic patients with unresectable stage IV CRC, whereas receiving upfront CT is a rational alternative without detrimental influence on survival or adverse outcomes compared with upfront PTR.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=27267
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