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31.
32.
Thyroid hormones play a crucial role in the neuroretinal maturation of the eye and central nervous system development. An experiment was conducted to survey the effects of thyroidectomy on rabbit retina. In this study, 10 male rabbits of New Zealand strips were divided into two groups of five animals each (control group and thyroidectomy group). Before surgery, the rabbits were maintained in 12-h light and 12-h dark. The animals were anesthetized with intraperitoneal injection of 10 mg/kg xylazine and 6 mg/kg ketamine, and bilateral thyroidectomy was performed. One and 2 weeks after surgery, the rabbits were sacrificed by humane methods. Then, retinas of the killed rabbits were isolated in the laboratory and examined by electron microscopy for evaluating cells and changes in inner segment, outer segment, outer limiting membrane, and outer nuclear layer. The result of this experiment showed vacuolization in inner section and endoplasmic reticulum of rabbit retina in group two. It was also observed that mitochondria of the inner segment of retina were larger and more circular than mitochondrial in control group; moreover, most of them had lost their crystal. The core in the control group was normal and had round to oval shape and distributed chromatin, but in thyroidectomy group, the mode of the nucleus was small and dark (pyknosis) and some nucleus had been destroyed. 相似文献
33.
Ali Aliabadi Seifollah N. Dehghani Maryam Farahmand Sara Varzandian Aboozar Dehghan 《Comparative clinical pathology》2013,22(6):1057-1060
To assess the effect of magnetic field in experimental tendon injuries, ten clinically healthy adult indigenous dogs were divided into two equal groups (control and experimental). The left superficial digital flexor tendon was exposed and three windows of 6 mm thickness, 3 mm length, and 2 mm intervals were made under general anesthesia. In the experimental group, the dogs were subjected to a magnetic field of 6?×?800 G for 30 days. The tendon biopsy was collected from the site of operation on the postoperative day 30. Histomorphological changes indicated low rate of inflammatory cells, high rate of mature fibroblast, and increased normal collagen fibers, and these were better in the experimental group. The biomechanical test revealed that the tendons of the dogs in the experimental group were more resistant than tendons of the dogs in the control group. The result of this study indicated that magnetic field therapy reduced edema and local swelling, enhanced proliferation of fibroblasts, and regulated arrangement of collagen fibers, providing a good noninvasive physical therapy for tendinous injuries. 相似文献
34.
Interchromosomal duplications of the adrenoleukodystrophy locus: a phenomenon of pericentromeric plasticity 总被引:13,自引:5,他引:13
Eichler EE; Budarf ML; Rocchi M; Deaven LL; Doggett NA; Baldini A; Nelson DL; Mohrenweiser HW 《Human molecular genetics》1997,6(7):991-1002
A 9.7 kb segment encompassing exons 7-10 of the adrenoleukodystrophy (ALD)
locus of the X chromosome has duplicated to specific locations near the
pericentromeric regions of human chromosomes 2p11,10p11, 16p11 and 22q11.
Comparative sequence analysis reveals 92-96% nucleotide identity,
indicating that the autosomal ALD paralogs arose relatively recently during
the course of higher primate evolution (5-10 million years ago). Analysis
of sequences flanking the duplication region identifies the presence of an
unusual GCTTTTTGC repeat which may be a sequence-specific integration site
for the process of pericentromeric- directed transposition. The breakpoint
sequence and phylogenetic analysis predict a two-step transposition model,
in which a duplication from Xq28 to pericentromeric 2p11 occurred once,
followed by a rapid distribution of a larger duplicon cassette among the
pericentromeric regions. In addition to facilitating more effective
mutation detection among ALD patients, these findings provide further
insight into the molecular basis underlying a pericentromeric-directed
mechanism for non- homologous interchromosomal exchange.
相似文献
35.
36.
Tamoxifen and its analogues 4-hydroxytamoxifen, toremifene, 4-
hydroxytoremifene, clomifene and droloxifene were tested for clastogenic
effects in a human lymphoblastoid cell line (MCL-5) expressing elevated
native CYP1A1 and containing transfected CYP1A2, CYP2A6, CYP2E1 and CYP3A4
and epoxide hydrolase and in a cell line containing only the viral vector
(Ho1). MCL-5 or Ho1 cells were incubated with 4-hydroxytamoxifen,
4-hydroxytoremifene, clomifene or droloxifene and the incidence of
micronuclei estimated. With MCL-5 cells there was an increase in
micronuclei with 4-hydroxytamoxifen, 4- hydroxytoremifene and clomifene but
not with droloxifene. With Ho1 cells only 4-hydroxytamoxifen and
4-hydroxytoremifene caused an increase in micronuclei. MCL-5 cells were
incubated with tamoxifen, 4- hydroxytamoxifen, toremifene, droloxifene,
clomifene or diethylstilbestrol (0.25-10 microg/ml) for 48 h and subjected
to 3 h treatment with vinblastine (0.25 microg/ml) to arrest cells in
metaphase. The incidence of cells with chromosomal numerical aberrations
(aneuploidy) was increased in cells treated with tamoxifen,
4-hydroxytamoxifen, toremifene, clomifene and diethylstilbestrol but not
droloxifene. The frequency of cells with structural abnormalities
(excluding gaps) was increased in cells treated with tamoxifen and
toremifene but not 4-hydroxytamoxifen, clomifene, droloxifene or
diethylstilbestrol. The clastogenic activities of tamoxifen (35 mg/kg),
toremifene (36.3 mg/kg), droloxifene (35.2 mg/kg) and diethylstilbestrol
(25 mg/kg) were compared in groups of four female Wistar rats. Each
chemical was dissolved in glycerol formal, administered as a single dose by
gavage and hepatocytes isolated by collagenase perfusion 24 h later. The
cells were cultured in the presence of epidermal growth factor (40 ng/ml)
for 48 h, colchicine (10 microg/ml) being added for the final 3 h of
incubation. At least 100 chromosomal spreads were examined from each animal
for the presence of numerical and structural abnormalities. The incidences
of aneuploidy following treatment were: tamoxifen 81%, toremifene 46%,
droloxifene 9.6%, diethylstilbestrol 45.7%, vehicle control 5.3%. The
incidences of chromosomal structural abnormalities excluding gaps were:
tamoxifen 4.3%, toremifene 0.8%, droloxifene 0.5%, diethylstilbestrol 0.8%,
control 0.5%. The incidence of chromosomal structural aberrations excluding
gaps in the treated animals was not statistically significantly different
from controls except in the tamoxifen-treated group. Tamoxifen (35 mg/kg
per os) and toremifene (36.3 mg/kg per os) were dosed to rats for 4 weeks
and chromosomal spreads made from hepatocytes. The incidences of aneuploidy
were: tamoxifen 94%, toremifene 57%, control 6.5%. The incidences of
chromosomal aberrations excluding gaps were: tamoxifen 12%, toremifene 1%,
control 0.5%. The incidence of tamoxifen-induced chromosomal structural
abnormalities was significantly elevated compared with control levels. The
results demonstrate that tamoxifen and toremifene are the only two drugs
tested in the study that cause chromosomal structural and numerical
aberrations in vitro and tamoxifen is the only drug that induces both these
effects in rat liver cells stimulated to divide in culture following oral
dosing. Since chromosomal mutations require cell division for their
manifestation and tamoxifen is the only compound of those tested that
causes hyperplasia in the rat liver, chromosomal aberrations and aneuploidy
in the rat liver would only be expected to occur following treatment with
tamoxifen alone, although aneuploidy could be induced by toremifene in
conjunction with a promoter such as phenobarbitone.
相似文献
37.
Ki-ras mutations are an early event and correlate with tumor stage in transplacentally-induced murine lung tumors 总被引:2,自引:2,他引:2
Leone-Kabler S; Wessner LL; McEntee MF; D'Agostino RB Jr; Miller MS 《Carcinogenesis》1997,18(6):1163-1168
A previous study from this laboratory demonstrated that treatment of
pregnant mice with 3-methylcholanthrene (MC) caused lung tumors in the
offspring at 1 year after birth, the incidence of which correlated with
fetal inducibility of Cyp1a1. Analysis by PCR amplification and allele-
specific hybridization (ASO) of paraffin-embedded tumors generated from
that study revealed the presence of point mutations in exon 1 of the Ki-
ras gene. This work has now been expanded by PCR amplification and ASO
analysis of 31 additional lesions. Point mutations were found in 37 of the
47 (79%) lesions analyzed in this and the previous study, the majority of
which were G-->T transversions in the first or second base of codon 12.
The mutational spectrum appeared to be dependent on the relative stage of
differentiation of the lesion, as both the incidence of mutation and type
of mutation produced correlated with malignant progression. Mutations
occurred in 60% of the hyperplasias, 80% of the adenomas and 100% of the
adenocarcinomas. In the lesions with mutations, GLY12-->CYS12
transversions occurred in 100% of the hyperplasias, 42% of the adenomas and
14% of the adenocarcinomas. The GLY12-->VAL12 transversions occurred in
none of the hyperplasias, 42% of the adenomas and 57% of the
adenocarcinomas. The remaining mutations, which consisted of ASP12
transitions and ARG13 transversions, occurred only in adenomas (17%) and
adenocarcinomas (29%). Between this study and our previous analyses, the
identity of the mutations obtained by ASO were confirmed by sequence
analysis of eight of the 37 lesions that harbored mutations at the Ki-ras
gene locus. There were no differences in the type or incidence of mutations
relative to the metabolic phenotype or sex of the mice. These data suggest
that mutational activation of the Ki-ras gene locus is an early event in
transplacental lung tumorigenesis, and that the type of mutations produced
by exposure to chemical carcinogens can influence the carcinogenic
potential of the tumor. This may have prognostic significance in
determining the malignant progression of the neoplasm.
相似文献
38.
ABSTRACT An unusual presentation of acute lymphoblastic leukaemia (ALL) in a 6-year-old girl is reported. She presented with unilateral cervical lymphadenopathy, a mixed obstructive/cholestatic jaundice and a progressive pancytopenia. Ultrasound examination revealed an obstructed common bile duct with gross thickening of the wall of the duct and intrahepatic bile duct dilatation. The jaundice resolved with high dose intravenous (i.v.) methylprednisolone. It is postulated that this was due to infiltration of the common bile duct, given the failure to demonstrate any other cause for the bile duct pathology. 相似文献
39.
40.