148 research outputs found
Age-Related Maculopathy: a biochemical and immunohistochemical study
Age-related maculopathy (ARM) is an age-related degenerative disorder of the central part
of the retina, the macula lutea (yellow spot). Essentially, ARM is a clinical diagnosis based
on funduscopical changes. It is customary nowadays to call the late stages of ARM,
geographic atrophy and neovascular (disciform) macular degeneration, age-related macular
degeneration (AMD)(Bird, et ai., 1995). These late stages result in severe and irreversible
visual impairment and tend to progress to the center of the macula (the fovea), where visual
acuity is affected most. Because AMD is usually a bilateral disorder, affected people loose
their ability to read, drive, and watch television (Macular-photocoagulation-study-group,
1993). The prevalence of AMD is 1-7% in people over 60, up to 14% over age 85.
Obviously, the number of people affected by AMD will enlarge, because of the increasing
age of the population (Ferris, 1983; Klein, el ai., 1992; Leibowitz, el ai., 1980; Vinding,
1989; Vingerling, et ai., 1995c). In fact, AMD is the mosl common cause of blindness in
the elderly in the weslern world and it is estimated that 640.000 people in the USA aged 75
years or older have signs of AMD (Klein, et ai., 1992), while in The Netherlands 57.000
persons suffer from AMD in at least one eye (Vingerling, et ai., 1995d). Although this
disease has been known for more than a century (Haab, 1888), knowledge on the
patllOgenesis of the affliction is still incomplete. Some risk-factors for ARM have been found
in epidemiologic studies. Current smokers have a three times increased risk to develop this
disease (Vingerling, et ai., 1995b), and cardiovascular diseases and early-menopause are
reported to be risk-factors as well (Vingerling, et ai., 1995a; Vingerling, et aI., 1995e).
There is still no adequate therapy for the majority of people disabled by AMD. Therefore,
it is necessary to intensify the research on ARM and AMD in order to understand the
pathogenesis of this disease. This knowledge may eventually lead to an adequate therapy or
to preventive measures for this severely invalidating disease
Soft tissue sarcomas at a glance: clinical, histological, and MR imaging features of malignant extremity soft tissue tumors
Soft tissue sarcomas comprise approximately 1% of malignant tumors. There are more than 50 subtypes, but pleomorphic sarcoma, liposarcoma, leiomyosarcoma, synovial sarcoma, and malignant peripheral nerve sheath tumor account for 75%. Differentiation between these subtypes is difficult because they often present with a painless enlarging mass, and share many histological and MR imaging features. Nonetheless, subdifferentiation is important because the different subtypes have different prognoses and therapeutic strategies. In this manuscript we discuss the clinical, histological, and MR imaging features of soft tissue sarcomas according to the WHO classification. An overview is provided and differentiating features are discussed that can help to narrow down the differential diagnosis
Somatostatin receptor 2A expression in choroidal neovascularization secondary to age-related macular degeneration
PURPOSE: The growth of ocular neovascularization is regulated by a balance
between stimulating and inhibiting growth factors. Somatostatin affects
angiogenesis by inhibiting the growth hormone-insulin-like growth factor
axis and also has a direct antiproliferative effect on human retinal
endothelial cells. The purpose of our study is to investigate the
expression of somatostatin receptor (sst) subtypes and particularly sst
subtype 2A (sst2A) in normal human macula, and to study sst2A in different
stages of age-related maculopathy (ARM), because of the potential
anti-angiogenic effect of somatostatin analogues. METHODS: Sixteen eyes
(10 enucleated eyes, 4 donor eyes, and 2 surgically removed choroidal
neovascular [CNV] membranes) of 15 patients with eyes at different stages
of ARM were used for immunohistochemistry. Formaldehyde-fixed
paraffin-embedded slides were incubated with a polyclonal anti-human sst2A
antibody. mRNA expression of five ssts and somatostatin was determined in
the posterior pole of three normal human eyes by reverse
transcriptase-polymerase chain reaction. RESULTS: The immunohistochemical
expression of sstA in newly formed endothelial cells and fibroblast-like
cells was strong in fibrovascular CNV membranes. mRNA of sst subtypes 1,
2A, and 3, as well as somatostatin, was present in the normal posterior
pole; sst subtypes 4 and 5 were not detectable. CONCLUSIONS: Most
early-formed CNV in ARM express sst2A. The presence of mRNA of sst subtype
2A was observed in normal human macula, and subtypes 1 and 3 and
somatostatin are also present. sst2A receptors bind potential
anti-angiogenic somatostatin analogues such as octreotide. Therefore,
somatostatin analogues may be an effective therapy in early stages of CNV
in ARM
Somatostatin receptor 2A expression in choroidal neovascularization secondary to age-related macular degeneration
PURPOSE: The growth of ocular neovascularization is regulated by a balance
between stimulating and inhibiting growth factors. Somatostatin affects
angiogenesis by inhibiting the growth hormone-insulin-like growth factor
axis and also has a direct antiproliferative effect on human retinal
endothelial cells. The purpose of our study is to investigate the
expression of somatostatin receptor (sst) subtypes and particularly sst
subtype 2A (sst2A) in normal human macula, and to study sst2A in different
stages of age-related maculopathy (ARM), because of the potential
anti-angiogenic effect of somatostatin analogues. METHODS: Sixteen eyes
(10 enucleated eyes, 4 donor eyes, and 2 surgically removed choroidal
neovascular [CNV] membranes) of 15 patients with eyes at different stages
of ARM were used for immunohistochemistry. Formaldehyde-fixed
paraffin-embedded slides were incubated with a polyclonal anti-human sst2A
antibody. mRNA expression of five ssts and somatostatin was determined in
the posterior pole of three normal human eyes by reverse
transcriptase-polymerase chain reaction. RESULTS: The immunohistochemical
expression of sstA in newly formed endothelial cells and fibroblast-like
cells was strong in fibrovascular CNV membranes. mRNA of sst subtypes 1,
2A, and 3, as well as somatostatin, was present in the normal posterior
pole; sst subtypes 4 and 5 were not detectable. CONCLUSIONS: Most
early-formed CNV in ARM express sst2A. The presence of mRNA of sst subtype
2A was observed in normal human macula, and subtypes 1 and 3 and
somatostatin are also present. sst2A receptors bind potential
anti-angiogenic somatostatin analogues such as octreotide. Therefore,
somatostatin analogues may be an effective therapy in early stages of CNV
in ARM
Decreased coronary flow reserve in hypertrophic cardiomyopathy is related to remodeling of the coronary microcirculation
BACKGROUND: Ischemia occurs frequently in hypertrophic cardiomyopathy
(HCM) without evidence of epicardial stenosis. This study evaluates the
hypothesis that the occurrence of ischemia in HCM is related to remodeling
of the coronary microcirculation. METHODS AND RESULTS: End-diastolic
septal wall thickness was significantly increased in patients with HCM
(25.8+/-2.9 mm) in comparison with cardiac transplant recipients (control
subjects: 11.4+/-3.0 mm; P<0.05). Although the diameter of the left
anterior descending coronary artery was similar in both groups (3.0+/-0.8
versus 3.0+/-0.5 mm, P=NS), the coronary resistance reserve
(CRR=CRRbasal/CRRhyperemic), corrected for extravascular compression
(end-diastolic left ventricular pressure), was reduced to 1.5+/-0.6 in HCM
(P<.05; control, 2.6+/-0.8). Arteriolar lumen (AL) divided by wall area
was lower in HCM (21+/-5% versus 30+/-4%; P<.05), and capillary density
tended to decrease (from 1824+/-424 to 1445+/-513 per mm2, P=.11) in HCM.
CRR was linearly related to normalized AL according to the formula CRR=O.1
AL-0.45 (r=.57; P<.05). Further analysis revealed that CRR, AL, and
capillary density were all linearly related to the degree of hypertrophy.
CONCLUSIONS: Decrements in CRR were related to changes of the coronary
microcirculation. Both the decrease in CRR and these changes in the
coronary microcirculation were related to the degree of hypertrophy. All
these factors might contribute to the well-known occurrence of ischemia in
this patient group
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