19 research outputs found
Quantitative assessment of normal and potentially premalignant epithelium at different levels of human colorectal crypts
The present study uses morphometric
techniques to assess whether altered differentiation
patterns exist in PPM which might reflect its premalignant
status. Samples were obtained from resected
malignant lesions of large bowels of 10 Chinese patients.
Normal (N) samples were biopsied from the margins of
each resected large bowel. Potentially premalignant
(PPM) mucosae were obtained from within 2 cm of the
margins of the malignant lesions. Tissues were processed
for histological examination and using strict criteria,
colorectal crypts were divided into basal (B), intermediate
(I) and surface (S) segments. Interactive
digitisation of sections from each group was used to
generate the following morphometric parameters in each
segment: nuclear profile circularity indices (NSF and
NCI); nuclear numerical density (NA and Nv); the
degree of deviation of the major nuclear axis in relation
to the epithelial-connective junction (AGDMAX); cell
height (CH); the distance between nuclear apex to cell
apex (DNACA); the distance between cell base to
nuclear apex (DCBNA); stratification index (SI) - the
ratio of DCBNA and CH; and the volume density
of mucous vacuoles in the reference epithelium
(VVMV,EP)I.n comparisons of different segments within
groups, the nuclei at the S segment of N and PPM crypts
were more irregular and less circular in shape than
nuclei from other segments. There was a shift of nuclear
profile shape (NSF and NCI) from circular to ellipsiodal
between B and S segments. In comparisons of similar
segments between groups, no significant nuclear shape
changes were detected in nuclei of PPM crypts when
compared with nuclei in similar segments of N crypts
and the pattern of nuclear shape alterations resembled
those of normal crypts. In comparisons of different
segments within groups of N and PPM crypts,
AGDMAX. DNACA, DCBNA, CH and S1 parameters
demonstrated that epithelial cells at the I segments have
more centrally positioned nuclei with the tallest
Offprint requests to: Dr. George L. Tipoe, Department of Anatomy,
Faculty of Medicine, The University of Hong Kong, Li Shu Fan Building,
5 Sasson Road, Hong Kong
* In memoriam
epithelial height when compared with epithelial cells in
other segments of both crypts. In B segments, nuclear
NA and Nv were almost double those of other segments
in both N and PPM crypts, with marked reductions in
these parameters between B and I segments. VVMV,EP
was significantly highest in the I segment and
significantly lowest in the S segment of both groups.
Both N and PPM crypts showed similar trends in
VVMV,EP within the crypt segments but when
comparing similar segments between both crypts, a
significant difference was detected only between S
segments. The alterations of nuclear shape and packing
densities, orientation and mucous content in N crypts
were similarly expressed in PPM crypts and distinct
differences in numerical density (Nv) and stratification
index existed in crypts between these two groups when
comparing similar segments. All values in PPM were
consistently lower when compared with N crypts. These
preliminary observations may represent a subtly altered
state of cellular differentiation in PPM which may be a
reflection of early preneoplastic transformation
Blood vessel morphometry in human colorectal lesions
Neovascularisation in tumours of different
cell origins has been well documented qualitatively. In
this report, we have assessed vascular architecture in
different pathological lesions of the colorectum by
quantifying blood vessel parameters in order to detect
subtle morphological changes using objective methods.
Colorectal tissue samples were obtained from
resected large bowels containing malignant tumours.
Biopsies were taken from defined sites in the resected
specimen and were classified as normal (N), potentially
premalignant mucosa (PPM), adenomatous polyp (P)
and adenocarcinoma (ADCA). Al1 tissues were fixed
in modified Karnovsky's fixative for 4 hrs and postfixed
in 1% Oso4 for 1 hr. Samples were processed for
EM under standardized procedures and embedded
in Epon. 0.5 pm semithin sections from five patients
per group were stained with toluidine blue. A multistage
systematic sampling procedure was adopted. The
imer outlines of al1 blood vessels in the lamina propria
(LP) were digitised using a Zeiss VIDAS Image
Analyzer at a final magnification of ~1,050T. he area of
the reference (LP) was also measured. No attempt was
made to distinguish between the different types of
vessel. The morphometric blood vessels parameters
quantified were volume density (V,), numerical density
(NA), length density (LV) and mean transverse sectional area (A).
Statistically significant differences in Vv and A were
detected between al1 groups except between N and PPM
and between P and ADCA. No significant differences in
NA and LV were present in any group comparisons. The
mean values of al1 parameters were the highest in
ADCA. Our results suggest that vasodilatation occurred
in order to provide an increased supply of nutrients to
support active growth and division of the transforming
cells. Such vasodilatation might also reflect the
inflammatory response to the presence of actively
growing malignant cells since activated immune cells
are able to release vasoactive substances
Overexpression of iNOS and down-regulation of BMPs-2, 4 and 7 in retinoic acid induced cleft palate formation
The present work studied the induction of
cleft palate formation in embryos developed from
pregnant BALB/c mice treated orally with retinoic acid
(RA). Previous studies on mature somatic cell types
showed that RA exerted inhibitory effects on inducible
nitric oxide synthase (iNOS) production. For the first
time, our study has shown that RA actually stimulates
significant expression of iNOS at specific zones of the
affected embryonic palatal tissues at three consecutive
stages, from gestation day 13 (GD13) to day 16 (GD16).
Enzymatically, iNOS facilitates intracellular nitric oxide
(NO) synthesis from L-arginine. When NO reacts with
reactive superoxides it may result in irreparable cell
injury. NO was also reported to induce apoptosis in some
mammalian cell systems. Based on our findings, we
propose that such an increase in NO production might be
associated with apoptosis in the embryonic palatal
tissues in the RA-treated mice. The detrimental effects of
NO resulted in a reduction in proliferating palatal cells
and therefore disturbed the normal plasticity of the
palatal shelves. With iNOS overexpression, our findings
also showed that there was significant concomitant
down-regulation in the expressions of Bone
Morphogenetic Proteins (BMPs) –2, 4, and 7 with
regional variations particularly in the palatal
mesenchymal cells for those embryos developing cleft
palate. Since specific spatial and temporal expressions of BMPs –2, 4, and 7 are critical during normal palatal
morphogenesis, any deficiency in the epithelialmesenchymal interaction may result in retarding growth
at the embryonic palatal shelves. Taken together, our
study has demonstrated cleft palate formation in the
BALB/c embryos involved overexpression of iNOS and
down-regulation of BMPs- 2, 4 and 7
Voluntary oral feeding of rats not requiring a very high fat diet is a clinically relevant animal model of non-alcoholic fatty liver disease (NAFLD)
Animal models used to study the
pathogenesis of non-alcoholic fatty liver disease
(NAFLD) are, in general, either genetically altered, or
fed with a diet that is extremely high in fat or
carbohydrates. Recent findings support the role of
oxidative stress, lipid peroxidation and inflammation as
probable causative factors. We hypothesize that not only
the amount of dietary fat, but the quality of fat is also
important in inducing NAFLD. Based on previous
observations that female rats fed a diet comprising
unsaturated fatty acids are susceptible to liver injury, we
proposed that female rats fed with a diet containing fish
oil and dextrose would develop pathological and
biochemical features of NAFLD. We fed a highly
unsaturated fat diet (30% fish oil) to female SpragueDawley rats (180-200g), consumed ad libitum for 8
weeks (NAFLD; n=6-8 ). Control animals (CF; n=6-8)
were fed with an isocaloric regular rat chow. At killing,
blood and liver samples were collected for serum alanine
aminotransferase (ALT), histology and molecular
analysis. Each histological sample was evaluated for
fatty liver (graded from 0 to 4+ according to the amount
of fatty change), necrosis (number of necrotic foci
(no./mm2
) and inflammation (cells per mm2
). The
amount of collagen formation was estimated based on
the amount of Sirius Red staining. Reverse transcriptase
polymerase chain reaction (RT-PCR) was carried out for
tumor necrosis factor alpha (TNF-α), cyclooxygenase-2
(COX-2), inducible nitric oxide synthase (iNOS),
adiponectin, glutathione peroxidase (GPx), superoxide
dismutase (Cu/Zn SOD) and catalase (CAT). Western
Blot analysis was done for cyclooxygenases-2 (COX-2),
inducible nitric oxide synthase (iNOS) and nitrotyrosine.
Electrophoretic mobility shift assay was performed for
nuclear factor-kappa B (NF-κB) activity. NAFLD rats
had a significantly higher serum ALT level, amount of
collagen formation, fatty liver, necrosis and
inflammation when compared with the chow-fed control
rats. mRNA and protein levels of NF-κB regulated
genes, which included TNF-alpha, COX-2 and iNOS
were also significantly (p<0.01; p<0.01; p<0.05
respectively) upregulated in the NAFLD group when
compared with the chow-fed control rats. mRNA levels
of antioxidants CAT and GPX were reduced by 35% and
50% respectively in the NAFLD group. However, Cu/Zn
SOD mRNA was similar in both groups. The mRNA
level of adiponectin was also reduced in NAFLD group.
NF-κB activity was markedly increased in the NAFLD
rats (p<0.01). The level of oxidative stress, represented
by the formation of nitrotyrosine, was significantly
elevated in the NAFLD rats (p<0.01). We conclude that
NAFLD rats demonstrated several features of NAFLD,
which included fatty liver, inflammation, necrosis,
increased oxidative stress, an imbalance between pro and
antioxidant enzymes mRNAs, reduced adiponectin
levels and upregulation of pro-inflammatory mediators.
We propose that female rats fed with a diet containing
highly unsaturated fatty acids are an extremely useful
model for the study of NAFLD
Role of melatonin in Alzheimer’s disease: From preclinical studies to novel melatonin-based therapies
Melatonin and novel melatonin-based therapies such as melatonin-containing hybrid molecules, melatonin analogues, and melatonin derivatives have been investigated as potential therapeutics against Alzheimer’s disease (AD) pathogenesis. In this review, we examine the developmental trends of melatonin therapies for AD from 1997 to 2021. We then highlight the neuroprotective mechanisms of melatonin therapy derived from preclinical studies. These mechanisms include the alleviation of amyloid-related burden, neurofibrillary tangle accumulation, oxidative stress, neuroinflammation, apoptosis, mitochondrial dysfunction, and impaired neuroplasticity and neurotransmission. We further illustrate the beneficial effects of melatonin on behavior in animal models of AD. Next, we discuss the clinical effects of melatonin on sleep, cognition, behavior, psychiatric symptoms, electroencephalography findings, and molecular biomarkers in patients with mild cognitive impairment and AD. We then explore the effectiveness of novel melatonin-based therapies. Lastly, we discuss the limitations of current melatonin therapies for AD and suggest two emerging research themes for future study
Inhibitors of inducible nitric oxide (NO) synthase are more effective than an NO donor in reducing carbon-tetrachloride induced acute liver injury
The exact functional role of nitric oxide
(NO) in liver injury is currently a source of controversy.
NO is enzymatically synthesized by nitric oxide
synthase (NOS). In this study, we assessed the role of
inducible NOS (iNOS) in carbon tetrachloride (CCl4)-
induced acute liver injury using inhibitors of iNOS, and
wani thN Oor dwointhoor.utA thdeu litN IOCSR imnhiicbei tworesr e(5 i-nmjeecthteydl iswoitthhi oCuCrela4
hemisulfate [SMT] and l-N6-(1-iminoethyl)-lysine [LNIL])
and an NO donor (Sodium Nitroprusside [SNP]).
Blood and liver tissues were collected for analysis.
Immunohistochemistry (IHC), serum alanine
aminotransferase (ALT), serum total 8-isoprostane
analysis, RT-PCR, Western Blotting (WB) and EMSA
were done. Our results showed increased levels of ALT,
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these effects but the effect was more pronounced with
SMT and L-NIL. RT-PCR, WB and IHC in CCl4–treated
mice demonstrated upregulation of TNF-a, iNOS, and
COX-2. The administration of iNOS inhibitors with
CCl4 diminished the expression of these
proinflammatory mediators. NF-kB was also
upregulated in CCl4-treated mice and was reversed in
mice pretreated with iNOS inhibitors. SNP pretreated
mice also showed a lower expression of COX-2 when
compared with CCl4 treated mice but TNF-a, iNOS and NF-kB activity were unaffected. We propose that a high
level of nitric oxide is associated with CCl4-induced
acute liver injury and the liver injury can be ameliorated
by decreasing the NO level with iNOS inhibitors and an NO donor with the former more effective in reducing
CCl4-induced liver injury