7 research outputs found
Cardiac Complications after Non-cardiac Surgery: Perioperative Risk Prediction and Reduction Strategies
__Abstract__
Introduction | 9
I
More than 200 million people worldwide undergo non-cardiac surgery annually. It is
estimated that 2-5 percent of these patients suffer a cardiac complication (i.e. myocardial
infarction, congestive heart failure, arrhythmia), resulting in death in approximately 0.5
percent of all patients.
The frequent occurrence of devastating cardiac complications necessitates a thorough
assessment of the risk of cardiac complications in every patient scheduled for non-cardiac
surgery. This risk is influenced by the preoperative condition of the patient and the
invasiveness of the planned procedure, and is modifiable by vari
Changes in epidermal radiosensitivity with time associated with increased colony numbers
Epidermal clonogenic cell survival and colony formation following
irradiation were investigated and related to radiosensitivity. A rapid in
vivo/in vitro assay was developed for the quantification of colonies
arising from surviving clonogenic cells in pig epidermis after
irradiation. Bromodeoxyuridine (BrdU)-labelled cells in full thickness
epidermal sheets were visualized using standard immunohistochemistry. In
unirradiated skin, approximately 900 BrdU-positive cells mm(-2) were
counted. In a time sequence experiment, BrdU-positive cell numbers
increased from an average of 900 cells mm(-2) to approximately 1400 cells
mm(-2) after BrdU-labelling for 2-24 h. In irradiated skin, colonies
containing >/=16 BrdU-positive cells were seen for the first time at days
14/15 after irradiation. The number of these colonies per cm(2) as a
function of skin surface dose yielded a cell survival curve with a
D(0)-value (+/-SE) of 3.9+/-0.6 Gy. This relatively high D(0)-value is
possibly due to a rapid fall off in depth dose distribution for the
iridium-192 source and consequently a substantial contribution of hair
follicular epithelium to colony formation. At 14/15 days after
irradiation, the ED(50) level of 33.6 Gy for the in vivo response of moist
desquamation corresponded with 2.7 colonies cm(-2). Surprisingly, the
number of colonies increased with time after irradiation with an estimated
doubling time of approximately 4 days, while the D(0)-value remained
virtually unchanged. This increase in colony numbers could be due to
migration of clonogenic cells, to the recruitment of dormant clonogenic
cell survivors by elevated levels of cytokines, or to both. Although
frequent biopsying caused increased cytokine levels, which had a systemic
effect on unirradiated skin, it had no influence on colony formation in
irradiated skin. Smaller colonies, containing 4-8 cells or 9-15 cells,
were abundant, particularly after higher doses, which resulted in higher
D(0)-values. The majority of these small colonies were abortive and did
not progress to larger colonies. There was no statistical evidence for
significant variations in the interanimal responses
Chemotherapy for pulmonary large cell neuroendocrine carcinomas: Does the regimen matter?
Copyrigh
Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?
Single dose irradiation response of pig skin: a comparison of brachytherapy using a single, high dose rate iridium-192 stepping source with 200 kV X-rays
An experimental brachytherapy model has been developed to study acute and
late normal tissue reactions as a tool to examine the effects of
clinically relevant multifractionation schedules. Pig skin was used as a
model since its morphology, structure, cell kinetics and radiation-induced
responses are similar to human skin. Brachytherapy was performed using a
microSelectron high dose rate (HDR) afterloading machine with a single
stepping source and a custom-made template. In this study the acute
epidermal reactions of erythema and moist desquamation and the late dermal
reactions of dusky mauve erythema and necrosis were evaluated after single
doses of irradiation over a follow-up period of 16 weeks. The major aims
of this work were: (a) to compare the effects of iridium-192 (192Ir)
irradiation with effects after X-irradiation; (b) to compare the skin
reactions in Yorkshire and Large White pigs; and (c) to standardize the
methodology. For 192Ir irradiation with 100% isodose at the skin surface,
the 95% isodose was estimated at the basal membrane, while the 80% isodose
covered the dermal fat layers. After HDR 192Ir irradiation of Yorkshire
pig skin the ED50 values (95% isodose) for moderate/severe erythema and
moist desquamation were 24.8 Gy and 31.9 Gy, respectively. The associated
mean latent period (+/- SD) was 39 +/- 7 days for both skin reactions.
Late skin responses of dusky mauve erythema and dermal necrosis were
characterized by ED50 values (80% isodose) of 16.3 Gy and 19.5 Gy, with
latent periods of 58 +/- 7 days and 76 +/- 12 days, respectively. After
X-irradiation, the incidence of the various skin reactions and their
latent periods were similar. Acute and late reactions were well separated
in time. The occurrence of skin reactions and the incidence of effects
were comparable in Yorkshire and Large White pigs for both X-irradiation
and HDR 192Ir brachytherapy. This pig skin model is feasible for future
studies on clinically relevant multifractionation schedules in a
brachytherapy setting