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Biomedical subjects

D Delbeke

Publications and source records attributed to D Delbeke.

At least 55 records · Page 3Linked to original sources
PubMed1993

Radionuclides in endocrine imaging.

Radiopharmaceuticals used in endocrine imaging encompass both standard and recently developed techniques used to diagnose diseases of the endocrine system. The initial part of this article deals with the characteristics of a suitable radionuclide/radiopharmaceutical required for successful scintigraphic endocrine imaging. The remainder of the article includes clinical applications and practical uses of developed scintigraphic agents in diagnosing disorders of the various endocrine glands. Finally, there is reference to the new and exciting neuropeptide imaging agent Octreoscan 111.

Endocrine Glands↗
PubMed1993

Estimation of left ventricular mass and infarct size from nitrogen-13-ammonia PET images based on pathological examination of explanted human hearts.

The purpose of this study was to develop a technique to quantify left ventricular mass and infarct size in chronic ischemic heart disease from PET images based on correlation with pathological examination of explanted human hearts. Fourteen hearts from patients with cardiomyopathy who had 13N-ammonia scans prior to orthoptic heart transplantation were studied. Accurate estimation of the relative infarct size was possible in patients with a well-delineated, nearly transmural infarct (r = 0.93, y = 1.1x - 0.7, n = 11). Both absolute and relative infarct mass measurements on PET images correlated well with pathological measurements. We identified a population of patients with patchy interstitial or subendocardial scarring with globally reduced perfusion, for which the infarct size could not be estimated using the criteria derived for the patients with well-delineated infarcts.

Adult↗
PubMed1992

The 'fading' Meckel's diverticulum. An unusual scintigraphic presentation.

The usual scintigraphic presentation of a Meckel's diverticulum is progressive accumulation of Tc-99m pertechnetate within the ectopic gastric mucosa that parallels uptake in the stomach. The authors present a case of an adult with acute gastrointestinal bleeding, negative endoscopic and radiologic evaluation, and atypical scintigraphy. An abnormal focus of uptake appeared at the same time as the stomach but faded away in the 15-minute image before reappearing while the stomach was still progressively accumulating the radioisotope. Meckel's diverticulum was confirmed by surgery. This case emphasizes the importance of scintigraphy in the evaluation of gastrointestinal bleeding, and it further emphasizes that any uptake that cannot be physiologically related is suspicious, even in a young adult.

Adult↗
PubMed1989

Diagnosis of allograft renal vein thrombosis.

Allograft renal vein thrombosis has been reported in 1 to 4% of the renal transplants. Salvage of the graft is possible only if there is prompt recognition and operative intervention. We present the case of a living-related renal transplant that was salvaged because of early diagnosis of allograft renal vein thrombosis by correlation of the radioisotopic angiogram, renogram and duplex doppler sonography.

Adolescent↗
PubMed1989

Correlative radionuclide and magnetic resonance imaging in evaluation of the spine.

The authors retrospectively compared magnetic resonance images and bone scintigraphy obtained from 144 patients. Fifty-six patients having a known primary malignancy were evaluated for metastases (Group 1), and 88 patients were evaluated for back pain (Group 2). Interpretation was normal in 36/144 patients (11 in Group 1 and 25 in Group 2), and similar abnormal foci were visualized in the osseous spine in 54/144 patients (32 in Group 1 and 22 in Group 2). Magnetic resonance imaging showed abnormalities in the osseous spine that were not visualized on bone scintigraphy in 43/144 patients (10 in Group 1 and 33 in Group 2); these included bone metastasis, benign neoplasm (hemangioma), Schmorl's node, intervertebral disk disease, and bone disease (osteophyte, spondylolisthesis, facet hypertrophy). In addition, magnetic resonance imaging showed epidural or paravertebral extension of the tumor or infection in 37/144 patients (30 in Group 1 and 7 in Group 2). Bone scintigraphy demonstrated abnormalities not visualized on magnetic resonance imaging in 11/144 patients (3 in Group 1 and 8 in Group 2). Bone scintigraphy showed abnormalities in locations not evaluated by magnetic resonance imaging but relevant to the symptomatology or disease in 42/144 patients (37 in Group 1 and 5 in Group 2). These data indicate that magnetic resonance imaging and bone scintigraphy are complementary. Bone scintigraphy remains the best screening procedure to show the location of abnormal areas in the spine and elsewhere in the skeleton. Magnetic resonance imaging is useful in differentiating neoplasm, infection, intervertebral disk disease, and, in some instances, degenerative bone disease.

Humans↗
PubMed1989

Correlative pediatric imaging.

Nuclear medicine, ultrasound, and magnetic resonance imaging (MRI) are considered ideal imaging modalities for pediatric patients. The future is even more promising for pediatric imaging with the development of newer and improved radiopharmaceuticals, instrumentation and diagnostic modalities such as positron emission tomography, labeled monoclonal antibodies, and faster dynamic and contrast enhanced MRI methods. However, correlation of more conventional imaging modalities with nuclear medicine, ultrasound and MRI remain essential for optimal patient care.

Bone Diseases↗
PubMed1988

Noninflammatory entities and the differential diagnosis of positive three phase bone imaging.

The greater sensitivity of skeletal imaging over radiography (93% vs. 50%) for the detection of early osteomyelitis is well known. The introduction of the three phase protocol has improved the specificity of skeletal imaging by eliminating various noninfectious entities; however, the occurrence of false-positive studies is not unusual. Four such cases have been observed by the authors in a group of 34 patients suspected of having osteomyelitis and who had positive three phase skeletal imaging. These includes a patient with giant cell tumor, synovial cell sarcoma, gouty arthritis, and Reiter's syndrome. A description of these cases and a brief review of several other entities associated with positive three phase bone imaging is the subject of this atlas article, which should serve as an aid in the differential diagnosis of this commonly performed scintigraphic procedure.

Adult↗
PubMed1988

Cat-scratch disease: report of a case with liver lesions and no lymphadenopathy.

The usual presentation of cat-scratch disease (CSD) is a subacute regional lymphadenitis following cutaneous inoculation. We present the case of a 10-yr-old white female with a 4-wk history of abdominal pain and fever, without associated lymphadenopathy. A 67Ga scintigram showed inhomogenous uptake by the liver. An abdominal computed tomographic (CT) scan revealed multiple low density lesions in the liver and the spleen, that were confirmed at laparotomy. Stellate microabscesses were seen on a wedge biopsy of the liver and a CSD antigen skin test was positive. CSD should be considered in the differential diagnosis of liver lesions, even in the absence of lymphadenopathy. This case emphasizes the importance of inhomogeneous 67Ga uptake by the liver.

Abscess↗
PubMed1986

Dopamine inhibits prolactin release when cyclic adenosine 3',5'-monophosphate levels are elevated.

We purified lactotrophs from pituitary tumors induced by estrogen in ovariectomized female Fischer 344 rats from 80% of the population before to more than 90% after purification through a continuous Percoll density gradient. The percentage of lactotrophs was evaluated by immunofluorescence. The patterns of PRL release stimulated by 100 nM TRH, 20 microM A23187 (a Ca++ ionophore), 50 nM 12-O-tetradecanoyl-phorbol-13-acetate (a C-kinase activator), or combinations of these agents, or inhibited by 10 microM dopamine were similar in perifused primary cultures of tumor lactotrophs to patterns in cultures of anterior pituitary cells from female retired breeders used previously. In particular, dopamine completely inhibited the release stimulated by forskolin. Intracellular cAMP concentrations and PRL accumulation in the medium were measured in monolayer cultures of purified tumor lactotrophs. In 9 separate experiments, forskolin (10 microM) increased intracellular cAMP concentrations more than 60-fold above control after 30 min of incubation. Preincubation (30 min) with dopamine (10 microM) reduced the cAMP accumulation caused by forskolin, but levels were still at least 20-fold above basal levels in most experiments. PRL release was stimulated 2-fold with forskolin alone, but there was no stimulation of PRL release by forskolin in the presence of dopamine even though cAMP levels were elevated above basal. Therefore, a decrease in cAMP levels is not necessary to inhibit PRL release, and dopamine must have a mechanism for inhibiting PRL release in addition to inhibiting adenylate cyclase.

Animals↗
PubMed1985

Comparison of patterns of prolactin release in GH4C1 cells and primary pituitary cultures.

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA, an activator of C-kinase), the cation ionophore A23187, forskolin (an activator of adenylate cyclase) and thyrotropin-releasing hormone (TRH) on prolactin release from anterior pituitary cells in primary culture were investigated and compared to the effects of these same agents on prolactin release from GH4C1 cells. In both GH4C1 cells and primary pituitary cultures, 100 nM TRH increased prolactin release 3- to 5-fold within 4 min after the stimulation started. This peak response was followed by a fall to a sustained increased rate of release approximately 1.5-fold above the basal rate. The decline after the early peak was slower in primary cultures than in GH4C1 cells. Addition of 20 microM A23187 to primary cultures caused a rapid 2- to 4-fold increase in release that fell to basal values within 12 min after the stimulation started. In GH4C1 cells, A23187 caused a rise in prolactin release of less than 2-fold that was sustained longer than the rise seen in primary cultures. Perifusion of either type of cells with 50 nM TPA caused a rapid 2- to 2.5-fold increase in release that also was sustained for 30 min or more in both types of cells. Perifusion with combined TPA and A23187 caused a 3- to 5-fold increase in rate of release from each cell type that declined rapidly to a 2-fold sustained release in primary cultures, and that declined more slowly in GH4C1 cells. Forskolin, 1 microM, had only a small effect by itself, but potentiated the effect of TPA or combined TPA and A23187 in both types of cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Stimulation of the adenosine 3',5'-monophosphate and the Ca2+ messenger systems together reverse dopaminergic inhibition of prolactin release.

Dopaminergic inhibition of PRL release stimulated by agents that affect cytosolic Ca2+ concentrations, C-kinase activity, and cAMP levels was studied in perifused rat anterior pituitary cells cultured on cytodex beads. We used A23187 (20 microM) to increase intracellular Ca2+, the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 50 nM) to stimulate C-kinase, forskolin (10 microM) to increase intracellular cAMP, and 8-bromo-cAMP to mimic cAMP. Dopamine (10 microM) inhibited PRL release to 20-60% of the basal release within 10 min. After 30 min of preincubation with dopamine, the absolute amount of release stimulated by 100 nM TRH was strongly inhibited, although the pattern of release, a quick burst followed by sustained release at a lower rate, was the same in the presence or absence of dopamine. A23187 (20 microM) caused a rapid burst of PRL release that subsided within 10 min, and TPA (50 nM) caused a sustained release that began within 4 min and continued for at least 30 min. TPA and A23187 combined caused a rapid burst of release followed by a sustained phase of release similar to that caused by TRH. Preincubation with dopamine inhibited the absolute amount of PRL release caused by A23187 alone, TPA alone, or the two combined, although, as with TRH, the pattern of release remained the same. Forskolin (1 or 10 microM) or 8-bromo-cAMP (3 mM) induced a 1.5- to 2-fold increase in PRL release, and this was completely prevented by dopamine. Preincubation with both dopamine and 8-bromo-cAMP or forskolin restored the amount of release stimulated by TPA alone or TPA and A23187 in the presence of dopamine to the level of release stimulated by these agents in the absence of dopamine. Therefore, activating either the cAMP messenger system or the Ca2+ system alone will not abolish dopaminergic inhibition, but activating the two together will. These results suggest that dopamine blocks release by inhibiting both adenylate cyclase and a step in the Ca2+ messenger system.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1984

Synergistic stimulation of prolactin release by phorbol ester, A23187 and forskolin.

The effects of 12-0-tetradecanoyl-phorbol-13-acetate (TPA), A23187, forskolin and thyrotropin-releasing hormone (TRH) on prolactin release from GH4C1 cells were compared. TPA caused a 2-fold release, maximum after 6 or more min, that was sustained for 30 min or more. A23187 caused only a small and variable response that peaked within 4 to 6 min. Combination of TPA and A23187 caused a rapid 3- to 5-fold increase in release that declined slowly. TRH increased prolactin release 3- to 5-fold, reaching a maximum within 4 min, followed by sustained release at lower rates. Forskolin had little effect by itself, but potentiated release caused either by combined TPA and A23187, or by TRH. These data are consistent with a model in which two branches of the Ca2+ messenger system participate in the action of TRH, a calmodulin branch and a C-kinase branch that interact to cause large amounts of sustained release. Forskolin, by regulating the cyclic AMP content of the cell determines the set point around which the Ca2+ messenger system operates.

Animals↗
PubMed1984

Difference in calcium requirements for forskolin-induced release of prolactin from normal pituitary cells and GH4C1 cells in culture.

We investigated the role of Ca++ in cAMP-stimulated PRL release from 1) primary cultures of male rat pituitary glands, 2) primary cultures of estrogen-induced pituitary tumors from Fischer rats, and 3) the pituitary tumor cell line GH4C1. Forskolin, an activator of adenylate cyclase, increased intracellular cAMP concentrations in GH4C1 cells at least 20-fold within 15 min. This increase occurred in the presence or absence of added extracellular Ca++ or in the presence of D600 or Co++. Forskolin increased PRL release from the three types of cells. The three systems differed in the Ca++ sensitivity of forskolin-induced release, but showed little difference in the Ca++ sensitivity of K+-induced release. This was shown in two ways. The cells were incubated either 1) in a medium without added Ca++ or 2) in the presence of a Ca++ channel inhibitor, D600. In normal cells, K+- and forskolin-induced release were equally inhibited when extracellular Ca++ was removed or D600 was added. In GH4C1 cells, Ca++ removal or D600 addition (100 microM) completely blocked K+-induced release, but had little effect on forskolin-induced release. The response of Fischer tumor cells was intermediate between those of normal and GH4C1 cells. 45Ca++ uptake by GH4C1 cells was not affected by forskolin, whereas the release of 45Ca++ from preloaded cells was increased slightly only 30 min after the addition of forskolin in three of four experiments. The difference in Ca++ requirements between normal and GH4C1 cells for forskolin stimulation may be due to the release of cellular Ca++ stores by cAMP. These stores may not be as large in normal cells as they are in GH4C1 cells, and therefore the requirement for extracellular Ca++ occurs. Alternatively, GH4C1 cells may release PRL by a mechanism different from that which normal cells use.

Animals↗
PubMed1984

Estimation of gestational age from measurements of fetal long bones.

The general practice of using fetal long bone growth charts to derive gestational age does not yield mathematically valid results. The authors tried to calculate gestational age from the lengths of long bones (femur, humerus, tibia, ulna) from 12 to 40 weeks of gestation. The combined use of the four bones allows a good estimation of gestational age that may be useful should the biparietal diameter measurement be unreliable, unobtainable, or abnormal.

Age Determination by Skeleton↗