PET examination of [11C]NNC 687 and [11C]NNC 756 as new radioligands for the D1-dopamine receptor

The benzazepines NNC 687 and NNC 756 have in animal studies been described as selective D₁-dopamine receptor antagonists. Both compounds have been labeled with¹¹C for examination by positron emission tomography (PET). In the present study central receptor binding was studied in monkeys and healthy men. After IV injection of both radioligands in Cynomolgus monkeys radioactivity accumulated markedly in the striatum, a region with a high density of D₁-dopamine receptors. This striatal uptake was displaced by high doses of the selective D₁-antagonist SCH 23390 (2 mg/kg) but not by the 5HT₂-antagonist ketanserin (1.5 mg/kg) or the selective D₂-antagonist raclopride (3 mg/kg). The cortical uptake after injection of [¹¹C]NNC 687 was not reduced in displacement experiments with ketanserin. The cortical uptake of [¹¹C]NNC 756 was reduced in displacement and protection experiments with ketanserin by 24–28% (1.5 mg/kg), whereas no reduction could be demonstrated on striatal uptake. In healthy males both compounds accumulated markedly in the striatum. For [¹¹C]NNC 687 the ratio of radioactivity in the putamen to cerebellum was about 1.5. For [¹¹C]NNC 756 the ratio was about 5. This ratio of 5 for [¹¹C]NNC 756 is the highest obtained so far for PET radioligands for the D₁-dopamine receptor.     

Improved differential diagnosis of hypercalcemia by hypocalcemic stimulation of parathyroid hormone secretion

In vitro experiments have indicated that in primary hyperparathyroidism (HPT) the hyperfunctioning glands have a set point error, i.e., they are not autonomous but regulate serum calcium around a hypercalcémie value. In contrast, parathyroid function is suppressed in patients with hypercalcemia of causes other than HPT (e.g., malignancy or sarcoidosis). The basal measurements of serum parathyroid hormone (PTH) levels, however, cannot, alone, separate with precision HPT from other causes of hypercalcemia.Lowering of calcium, in order to stimulate secretion of PTH, was, therefore, achieved by either infusion of Na₂ EDTA (24 mg/kg per hr) for 1 hour, or intramuscular injection of 100 IU salmon calcitonin. All 35 patients with primary HPT displayed a significant increase of serum PTH concentrations, evaluated by a midregion/intact hormone assay, during the EDTA infusion, which lowered plasma ionized calcium by an average of 0.16 mmol/l. The injection with calcitonin reduced the calcium concentrations by 0.10 mmol/l after 8 hours and caused a rise in PTH in 80% of HPT patients. With both tests, the secretory response by PTH to the reduction of plasma calcium was generally evident while the patients were still hypercalcemic. In 32 patients with other causes for hypercalcemia, primarily malignancy and sarcoidosis, similar reductions of plasma ionized calcium were obtained. In contrast to the HPT patients, none of them raised their serum PTH values during the test. Thus, stimulation of PTH secretion by a moderate reduction of serum calcium considerably improves the differential diagnosis of hypercalcemia since a significant secretory response appears to be exclusive for HPT.

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Resumen Experimentos in vitro han señalado que en el hiperparatiroidismo primario (HPT) las glándulas hiperfuncionantes tienen un error en su set point, o sea que no son autónomas sino que regulan el calcio sérico alrededor de un valor hipercalcémico. Por el contrario, la función paratiroidea es suprimida en pacientes con hipercalcemia de causa diferente de HPT (e.g., neoplasias malignas o sarcoidosis). Las mediciones basales de los nivelés séricos de hormona paratiroidea (PTH) de por sí no son capaces de diferenciar con precision entre el HPT y la hipercalcemia de otras causas.La disminución del nivel de calcio sérico, con el objeto de estimular secreciones de PTH, fue lograda con la infusión de Na₂ EDTA (24 mg/Kg por hora) por 1 hora o la inyección i.m. de 100 UI de calcitonina de salmón.Todos los 35 pacientes con HPT primario exhibieron un aumento significativo de las concentraciones séricas de PTH, determinadas mediante la medición de la fraction media/intacta de PTH en el curso de la infusion de EDTA, la cual redujo el nivel plasmático de calcio ionizado en un promedio de 0.16 mmol/l. La inyección de calcitonina redujo las concentraciones de sérico en 0.10 mmol/l a las 8 horas y resultó en un aumento de la PTH en 80% de los pacientes con HPT. Con ambas pruebas la respuesta secretoria de PTH a la reducción del calcio plasmático generalmente apareció evidente aún mientras los pacientes se hallaban hipercalcémicos.En 32 pacientes con hipercalcemia de causa diferente, se lograron reducciones similares de la concentration plasmática del calcio ionizado. Por el contrario de lo observado en los patientes con HPT, ninguno demostró elevatión de sus niveles séricos de PTH en el curso de la prueba. Por consiguiente, el estímulo de la secretión de PTH mediante la reductión moderada de calcio sérico incrementa considerablemente la (ie501-01)acidad de establecer el diagnóstico diferencial de la hipercalcemia, puesto que una significativa respuesta secretoria parece ser caracteristíca exclusiva del HPT.

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Résumé L'expérimentation in vitro a démontré que dans l'hyperparathyroïdisme (HPT), les glandes hyperactives ont un point mort erroné, c'est-à-dire qu'elles ne sont pas autonomes mais règlent la calcémie autour d'une valeur de référence déjà hypercalcémique. En revanche, la fonction parathyroîde est déprimée chez le patient dont l'hypercalcémie est due à une cause autre que l'HPT (cancer ou sarcoïdose par exemple). La mesure des niveaux de base de la parathormone (PTH), cependant, ne permet pas de distinguer l'hypercalcémie de l'HPT des autres causes d'hypercalcémie avec précision.Dans le but de stimuler la sécrétion de PTH, la calcémie était abaissée soit en perfusant les patients avec une solution de Na₂ EDTA (24 mg/Kg) pendant une heure, soit par une injection intramusculaire de 100 U de calcitonine de saumon.Trente-cinq patients ayant un HPT primitif présentaient une augmentation significative des concentrations en PTH sérique, évaluée par l'étude immunologique de la portion moyenne intacte, pendant la perfusion d'EDTA. La portion de calcium plasmatique ionisée a été abaissée en moyenne de 0.16 mmol/l. L'injection de calcitonine a réduit la concentration en calcium par 0.10 mmol/l après huit heures et a provoqué une augmentation en PTH chez 80% des patients à HPT. Quel que soit le test, la réponse de PTH à la réduction de calcium plasmatique était généralement évidente alors que le patient était toujours hypercalcémique.Chez 32 autres patients ayant pour cause d'hypercalcémie cancer ou sarcoïdose, des réductions similaires en calcium plasmatique ionisé ont été obtenues. Aucun malade, contrairement aux patients HPT, n'a vu son niveau de PTH monter pendant le test. Ainsi, la stimulation de sécrétion de PTH par une réduction modérée de calcium sérique améliore considérablement le diagnostic différentiel des hypercalcémies puisque la réponse sécrétoire significative paraît être le fait exclusif des HPT.

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Presented at the International Association of Endocrine Surgeons in Sydney, Australia, September, 1987.

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Supported by the Swedish Medical Research Council.     

The Stockholm breast cancer screening trial — 5-year results and stage at discovery

In screening programmes it is important to assess a preliminary effectiveness of the screening method as soon as possible in order to forecast survival figures. In March 1981 a controlled single-view mammographic screening trial for breast cancer was started in the south of Stockholm. The population invited for screening mammography consisted of 40,000 women aged 40–64 years, and 20,000 women served as a well-defined control group. The main aim of the trial was to determine whether repeated mammographic screening could reduce the mortality in the study population (SP) compared to the control population (CP).The cumulative number of advanced mammary carcinomas in the screening and the control populations from the first five years of screening have shown a tendency towards more favourable stages in the screened population aged 40–64 years. A breakdown by age suggests an effect in age group 50–59 years, but not yet in age groups 40–49 and 60–64 years.When comparing the rates of stage II+ cancer, an increased number is found in the study group. As the total rate of breast cancer is higher in SP than in CP, there ought to be a concealed group of stage II+ cancers in the CP which makes the comparison biased. A new approach has been designed, where an estimation of the hidden number of stage II+ cancers in CP is added to the clinically detected cases, and in this respect a comparison has shown a decrease in the cumulative number of advanced cancers in the SP in relation to the CP (p<0.05). According to this it could be important to add the estimated number of undetected, hidden cases in the control group in order to utilize the difference in detection rate in the screening- and control group respectively.     

The rate of polymerization of rabbit skeletal muscle actin is enhanced by polyethylene glycol

Summary The effect of polyethylene glycol on the kinetics of actin polymerization was determined by monitoring the enhancement in the fluorescence of pyrenyl-labelled actin. The polymerization of actin at 15 mM KCl was in addition followed by viscometry and light scattering. All three methods showed that the overall rate of polymerization of actin increased 3-4-fold when the concentration of polyethylene glycol was increased from 0 to 6% (w w^–1). A further increase in polyethylene glycol concentration to 10% (w w^–1) caused a relatively small contribution to the increase in the rate of polymerization. The enhancement of the overall rate of polymerization by polyethylene glycol was also reflected in a significant decrease in the lag time observed when the time course of polymerization was followed by viscometry and light scattering. The steady-state value of fluorescence enhancement and critical concentration of actin were also influenced by polyethylene glycol and the results showed that the extent of polymerization was increased by an increase in the concentration of polyethylene glycol in solution. The effect of polyethylene glycol on both rate and extent of polymerization persisted at physiological salt concentration (150mm KCl, 2mm MgCl₂). Since the rate of elongation was affected only to a small extent by polyethylene glycol, we propose that its main effect is on nucleation.     

Intraperitoneal injection of cholecystokinin elicits sleep in rabbits

Cholecystokinin (CCK) reduces food intake and promotes non-rapid-eye-movement sleep (NREMS) in rats. The purpose of present experiments was to determine if CCK is somnogenic in rabbits; another species in which CCK suppresses feeding. White New Zealand rabbits were treated intracerebroventricularly (ICV; 0.05, 0.5 and 2 μg) or intraperitoneally (IP; 2.5, 10 and 40 μg/kg) with CCK or saline, and sleep-wake activity and brain temperature (T_br) were recorded for 6 h. Injections of 10 and 40 μg/kg CCK IP elicited a decrease in wakefulness and an increase in NREMS during the first hour postinjection. The hypnogenic effects were accompanied by a decrease in T_br. After the IP injection of a lower dose (2.5 μg/kg) a slight, nonsignificant increase in NREMS during the first hour postinjection was followed by a decrease in NREMS. ICV injections of CCK had relatively small inhibitory effects on sleep. We conclude that circulating, hormone CCK might be a hypnogenic signal with a peripheral site of action.     

Epidermal growth factor and trefoil factor family 2 synergistically trigger chemotaxis on BEAS-2B cells via different signaling cascades

Injured areas of the respiratory epithelium are subject to rapid repair by the migration of adjacent epithelial cells, a process termed "restitution". Rapid re-epithelialization is promoted by interactions between migrating cells and the extracellular matrix proteins. Furthermore, epidermal growth factor (EGF) as well as trefoil factor family (TFF) peptides are well known regulators of epithelial restitution due to their motogenic effects. Migration of the human bronchial epithelial cell line BEAS-2B in modified Boyden chambers was used as a model system for airway restitution. EGF or recombinant human TFF2 or TFF3 showed mainly chemotactic activity. The motogenic response was strictly dependent upon a haptotactic substrate, but to different degrees. EGF induced phosphorylation of extracellular signal-regulated kinases (ERK) 1/2, c-Jun-N-terminal kinase, p38, Akt, and p70S6K in BEAS-2B cells. Using specific inhibitors, the signaling cascades responsible for the motogenic response were shown to differ drastically when EGF was compared with TFF2. The motogenic effect of TFF2 was previously demonstrated to depend on ERK1/2 and protein kinase C activation; whereas the EGF-triggered motogenic response was completely independent of ERK1/2 activation but sensitive to the inhibition of phosphoinositide 3-kinase, p38, protein kinase C, or nuclear factor kappaB. However, the motogenic effects of EGF and TFF2 are additive. These data suggest that luminal EGF and TFF peptides can act synergistically in the human respiratory epithelium to enhance rapid repair processes in the course of diseases such as asthma.