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991.
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994.
Repopulation of marrow after transplantation: MR imaging with pathologic correlation 总被引:3,自引:0,他引:3
Sixty-seven magnetic resonance (MR) studies of the lumbar spine were performed in 15 patients with bone marrow transplants, and the appearance of marrow regeneration on MR images was correlated with results of bone marrow biopsy and pathologic examination. After transplantation, T1-weighted MR images of vertebral marrow showed a characteristic band pattern consisting of a peripheral zone of intermediate signal intensity and a central zone of bright signal intensity. Reciprocal changes were identified on short inversion time inversion recovery images. At histologic examination the central zone corresponded to fatty marrow; the peripheral zone corresponded to a zone of regenerating hematopoietic cells. Posttransplantation T1 and T2 relaxation times of the entire vertebral marrow were calculated from the spin-echo images; no statistically significant trends in relaxation times were noted. Knowledge of the normal MR pattern of marrow regeneration after transplantation may be useful in screening for residual marrow disease, determining marrow engraftment, and differentiating marrow repopulation with normal versus malignant cells. 相似文献
995.
Clegg CH; Rulffes JT; Haugen HS; Hoggatt IH; Aruffo A; Durham SK; Farr AG; Hollenbaugh D 《International immunology》1997,9(8):1111-1122
Expression of gp39 on activated T cells provides a co-stimulatory signal in
peripheral lymphoid tissue that regulates humoral and cell- mediated
immunity. The function of gp39 and its receptor CD40 in thymus remains
uncertain. Here we report that overexpression of gp39 in transgenic mouse
thymus caused a dose-dependent decline in thymocyte numbers (> 500
fold), loss of cortical epithelium and expansion of CD40+ medullary cells.
Transplantation of transgenic bone marrow into normal mice indicated that
gp39 significantly diminished thymocyte viability in the context of a
'normal' thymic environment. The peripheral tissues of transgenic mice also
accumulated abnormalities in a transgene dose-dependent manner that
involved inflammation and lymphoid tissue hypertrophy. Animals with the
highest transgene copy numbers acquired a lethal inflammatory bowel disease
marked by the infiltration of gp39+ T cells and CD40+ cells into diseased
tissues. Examination of cells overexpressing gp39 suggested that these
defects were caused, in part, by the saturation of a mechanism that
sequesters gp39 inside non-activated cells and thus protects the immune
system from inappropriate gp39-CD40 interaction. These results establish a
regulatory role for gp39 in thymus function and a causal relationship in
mediating chronic inflammatory disease.
相似文献
996.
997.
998.
Urinary mutagenicity as a biomarker in workers exposed to benzidine: correlation with urinary metabolites and urothelial DNA adducts 总被引:1,自引:1,他引:1
DeMarini DM; Brooks LR; Bhatnagar VK; Hayes RB; Eischen BT; Shelton ML; Zenser TV; Talaska G; Kashyap SK; Dosemeci M; Kashyap R; Parikh DJ; Lakshmi V; Hsu F; Davis BB; Jaeger M; Rothman N 《Carcinogenesis》1997,18(5):981-988
Urinary mutagenicity has been used in occupational and epidemiological
studies for over two decades as a cost-effective, general biomarker of
exposure to genotoxic agents. However, few studies have compared urinary
mutagenicity to additional biomarkers determined among low- and
high-exposed groups. To address this issue, we evaluated the relationship
between urinary mutagenicity and other types of biomarkers in a
cross-sectional study involving 15 workers exposed to the urinary bladder
carcinogen benzidine (BZ, high exposure), 15 workers exposed to BZ-dyes
(low exposure), and 13 unexposed controls in Ahmedabad, India. Urinary
organics were extracted by C18/methanol and evaluated for mutagenicity in
the presence of S9 in the Salmonella strain YG1024, which is a frameshift
strain that overproduces acetyltransferase. The results were compared to
biomarker data reported recently from the same urine samples (Rothman et
al., Proc. Natl Acad. Sci. USA, 93, 5084- 5089, 1996) that included a
metabolite biomarker (the sum of the urinary levels of BZ +
N-acetylbenzidine + N,N'-diacetylbenzidine) and a DNA adduct biomarker [a
presumptive N-(3'-phosphodeoxyguanosin-8-yl)- N'-acetylbenzidine (C8dG-ABZ)
DNA adduct in exfoliated urothelial cells]. The mean +/- SE urinary
mutagenicity (revertants/micromol of creatinine) of the low-exposure
(BZ-dye) workers was 8.2 +/- 2.4, which was significantly different from
the mean of the controls (2.8 +/- 0.7, P = 0.04) as was that of the mean of
the high-exposure (BZ) workers (123.2 +/- 26.1, P < 0.0001). Urinary
mutagenicity showed strong, positive correlations with urinary metabolites
(r = 0.88, P < 0.0001) and the level of the presumptive C8dG-ABZ
urothelial DNA adduct (r = 0.59, P = 0.0006). A strong association was
found between tobacco use (bidi smoking) and urinary mutagenicity among the
controls (r = 0.68, P = 0.01) but not among the exposed workers (r = 0.18,
P = 0.11). This study confirms the ability of a biomarker such as urinary
mutagenicity to detect low-dose exposures, identify additional genotoxic
exposures among the controls, and correlate strongly with urinary
metabolites and DNA adducts in the target tissue (urinary bladder
epithelia) in humans.
相似文献
999.
Protection against induction of mouse skin papillomas with low and high risk of conversion to malignancy by green tea polyphenols 总被引:2,自引:1,他引:2
We earlier showed that a polyphenolic fraction isolated from green tea
(GTP) affords protection against tumor promotion and tumor progression in
SENCAR mouse skin. The present study was designed to further evaluate the
protective effect of GTP against the induction and subsequent progression
of papillomas to squamous cell carcinomas (SCCs) in experimental protocols
where papillomas were developed with a low or high probability of their
malignant conversion. Topical application of GTP (6 mg/animal) 30 min prior
to that of 12-O-tetradecanoylphorbol-13- acetate (TPA) either once a week
for 5 weeks (high risk TPA protocol) or once a week for 20 weeks (low risk
TPA protocol) or mezerein (MEZ) twice a week for 20 weeks (high risk MEZ
protocol) in 7,12- dimethylbenz[a]anthracene (DMBA)-initiated mouse skin
resulted in significant protection against skin tumor promotion in terms of
tumor incidence (32-60%), multiplicity (49-63%) and tumor volume/mouse (73-
90%) at the termination of the experiment at 20 weeks. In three separate
malignant progression experiments when papilloma yield in DMBA- initiated
and TPA or MEZ promoted low and high risk protocols was stabilized at 20
weeks, animals were divided into two subgroups. These animals were either
topically treated twice weekly with acetone (0.2 ml/animal, spontaneous
malignant conversion group) or with GTP (6 mg/animal in 0.2 ml acetone) for
an additional period of 31 weeks. During these treatment regimens, all
suspected carcinomas were recorded and each one was verified
histopathologically either at the time when tumor-bearing mouse
died/moribund or at the termination of the experiment at 51 weeks. GTP
resulted in significant protection against the malignant conversion of
papillomas to SCC in all the protocols employed. At the termination of the
experiment at 51 weeks, these protective effects were evident in terms of
mice with carcinomas (35- 41%), carcinomas per mouse (47-55%) and percent
malignant conversion of papillomas to carcinomas (47-58%). The kinetics of
malignant conversion suggest that a subset of papillomas formed in the
early phase of tumor promotion in all the protocols had a higher
probability of malignant conversion into SCCs because all the positive
control groups (acetone treated) produced nearly the same number of
carcinomas (33-38 in a group of 20 animals) at the end of the progression
period. In the GTP- treated group of animals the number of carcinomas
formed was less (14- 20 in a group of 20 animals), which shows the ability
of GTP to protect against the malignant conversion of papillomas of higher
probability of malignant conversion to SCCs. The results of this study
suggest that irrespective of the risk involved, GTP may be highly useful in
affording protection against skin cancer risk.
相似文献
1000.
SK VIRMANI 《Medical Journal Armed Forces India》1997,53(3):163-168
Three hundred and five cases of high altitude pulmonary oedema (HAPO) hospitalised in eastern Himalayan region have been analyzed. Incidence of HAPO was 5.5 per cent. Eighty per cent cases occurred during latter half of the year. Fifty six per cent of cases belonged to the third decade of life. HAPO cases occurred most commonly between the height of 2740 m to 5960 m. Eighty three per cent cases developed symptoms within 72 hours of induction to high altitude and 65.9 per cent suffered from the illness despite complete acclimatization. Breathlessness, headache and cough were the commonest symptoms. Tachycardia and tachypnoea was present in all cases. Twenty five per cent cases showed various ECG abnormalities. Mortality rate was 0.98 per cent.KEYWORDS: Altitude, ECG abnormalities, Cerebral oedema, Pulmonary oedema 相似文献