[Cutaneous neuroendocrine carcinoma. Apropos of a case]

Cutaneous neuroendocrine carcinoma (CNEC) is a rare tumour. We report the case of a 75-year old woman affected with a rapidly progressive CNEC of the right cheek which kept recurring despite surgical excision followed by radiotherapy. The clinical features of CNEC are not specific. The tumour is located in the dermis, and the tumoral cells (Merkel cells) have a monotonous appearance. Gould's classification of these carcinomas into three types has a prognostic value. Immunohistochemistry is a mandatory complement to light microscope examination. It is very difficult to distinguish between CNEC and metastasis from a visceral small cell carcinoma. Treatment consists of surgery combined with radiotherapy. Chemotherapy was very successful in our patient and should be considered in other cases.

[Value of liver biopsy in internal medicine. Apropos of a series of 300 puncture biopsies]

Between April 1976 and March 1987, in an Internal Medicine department some 300 unguided percutaneous liver biopsies were performed, using the Tru-Cut excision needle. The procedure contributed to the diagnosis in 76.2% of the cases. In alcoholism-related pathology with its specific lesions, liver biopsy is particularly useful in diagnosing incipient fatty degeneration and hepatitis and helps in the prognosis of cirrhosis. In chronic hepatitis, it asserts the diagnosis and provides aetiological and prognostic data. The finding of granulomas at histology sometimes clinches a hitherto undecided diagnosis : sarcoidosis or tuberculosis? The diagnosis of drug-induced hepatitis rests on convergent clinical, biochemical and histological elements. In blood diseases, liver biopsy is of interest on three scores: it shows whether or not the liver is involved, detects intercurrent complications and evaluates the extent of the lesions before treatment. When performed after ultrasonography, it enables intrahepatic cholestasis to be recognized and extrahepatic cholestasis, unidentified by ultrasounds, to be suspected. In primary biliary cirrhosis, it confirms the diagnosis and informs on the severity and progressiveness of the disease. In hepatic cancers, liver biopsy has recently been superseded by computerized tomography and ultrasonography. Finally, it largely contributes to the diagnosis of overload disease and evaluates their activity and their impact on the liver.

The influence of sodium omission on alpha 2-adrenergic inhibition of insulin release by mouse islets

The mechanisms by which activation of alpha 2-adrenoceptors inhibits insulin release are still incompletely understood. This study, performed with isolated mouse islets, identifies a possible role of Na+ in this inhibition. Regardless of the stimulus used to induce insulin release, the inhibitory effect of low concentrations of clonidine (0.01-0.1 microM) was markedly smaller in the absence of Na+ (with choline or lithium as substitute) than in its presence. The effectiveness of a high concentration of clonidine (1 microM) was, however, not affected by Na+ omission. The results indicate either that Na+ omission indirectly counteracts an effect of clonidine (e.g. on a membrane permeability or on Ca2+ handling), or that Na+ is directly involved in a cellular process (e.g. a Na+ current or the Na+/H+ exchange) controlled by alpha 2-adrenoceptors.

Difference in the potentiating effect of adenosine triphosphate and alpha, beta-methylene ATP on the biphasic insulin response to glucose

1. The effects of exogenous adenine nucleotides and structural analogues on the biphasic insulin response to an increase of glucose concentration in the physiological range (from 4.2 to 8.3 mM) were studied in the isolated perfused rat pancreas. Purinoceptor agonists were added either simultaneously or 15 min before increasing glucose. 2. ATP and ADP at 16.5 microM were ineffective per se in the presence of the non stimulatory glucose concentration (4.2 mM) but markedly potentiated the biphasic insulin response to glucose rise in both experimental protocols. 3. Two more stable analogues of ATP and ADP (adenylylimidodiphosphate and alpha, beta-methylene ADP (alpha, beta-MeADP)) at 16.5 microM behaved like the natural compounds: they were ineffective at a glucose concentration of 4.2 mM and potentiated both phases of insulin response to glucose rise. 4. alpha, beta-MeATP added simultaneously with the high glucose concentration, markedly potentiated the first phase of insulin response to glucose rise but did not potentiate the second one. When alpha, beta-MeATP infusion began 15 min before glucose rise, the biphasic response to glucose was not potentiated, in contrast to what occurred with ATP. 5. In the presence of alpha, beta-MeATP, the ATP potentiating effect was unaffected. 6. It is concluded that ATP and ADP, via activation of beta cell P2 gamma purinoceptors, potentiates the biphasic insulin response to an increase of glucose concentration. On the other hand, alpha, beta-MeATP did not behave like natural and other structural analogues of ATP and ADP: this difference appears not to be the consequence of desensitization of beta cell P2 gamma purinoceptors by alpha, beta-MeATP.

Effects of extracellular adenine nucleotides on the electrical, ionic and secretory events in mouse pancreatic beta-cells

1. The mechanisms whereby extracellular adenine nucleotides modulate pancreatic beta-cell function were studied with mouse islets stimulated by 15 mM glucose. 2. Adenosine 5'-triphosphate (ATP) and adenosine 5'-diphosphate (ADP) (100 microM) inhibited insulin release, 45Ca efflux and 86Rb efflux from islet cells, and decreased electrical activity in beta-cells. These changes were rapid but small and transient. 3. alpha,beta-Methylene ADP caused a rapid and sustained inhibition of insulin release, 45Ca efflux and 86Rb efflux from islet cells. It also produced a slight hyperpolarization of the beta-cell membrane, with sustained modification of the pattern but only transient decrease of the intensity of the electrical activity. In the absence of extracellular Ca2+, alpha,beta-methylene ADP increased 45Ca and 86Rb efflux without changing insulin release. Most effects of alpha,beta-methylene ATP were qualitatively similar but quantitatively smaller than those of the ADP-analogue. 4. Adenylylimido-diphosphate (AMP-PNP) slightly increased 45Ca and 86Rb efflux and potentiated insulin release in the presence of extracellular Ca2+. However, its effects on electrical activity in beta-cells were qualitatively similar to those of the alpha,beta-methylene analogues. 5. The small effects of ATP and ADP could result from their degradation into adenosine. alpha,beta-Methylene ADP appears to increase K+ permeability of the beta-cell membrane and to produce a second, intracellular, effect which largely contributes to the inhibition of insulin release. Another recognition site, with higher affinity for triphosphate derivatives, could mediate the small stimulatory effects of AMP-PNP.

Diabetes and impaired response of glucagon cells and vascular bed to adenosine in rat pancreas

Previous studies have shown that adenosine, by activation of purinergic A2-receptors, stimulates glucagon secretion and increases vascular flow rate in isolated perfused pancreases from nondiabetic rats. Because alpha-cell function and blood flow control are known to be disturbed in diabetes, we investigated whether adenosine was still effective in streptozocin-induced diabetic (STZ-D) rats. Our experiments were performed on isolated perfused rat pancreases. Whereas, in normal rats, adenosine (1.65 microM) induced a 200% increase in glucagon output and a 25% rise in the pancreatic vascular flow rate, in rats diabetic for 5-6 wk, this nucleoside was ineffective on glucagon secretion, and its vasodilatory effect was strongly reduced. Long-term in vivo insulin treatment that reversed high glycemia levels was able to restore in large part both adenosine effects. In contrast, a short-term in vitro pretreatment with insulin was unable to restore the nucleoside effects. We conclude that STZ-D suppresses the stimulatory effect of adenosine on alpha-cells and strongly reduces its vasodilator properties; these abnormalities may be corrected in large part by long-term insulin treatment with normalization of glycemia.

Membrane and intracellular effects of adenosine in mouse pancreatic beta-cells

Mouse islets were used to study the effects of adenosine and its stable analogue L-N6-phenylisopropyladenosine (L-PIA) on pancreatic beta-cell function. At a high concentration (500 microM), adenosine augmented glucose-induced electrical activity in beta-cells and potentiated insulin release. These effects were prevented by the inhibitor of nucleoside transport nitrobenzylthioguanosine. They probably result from the metabolism of adenosine by beta-cells. At a lower concentration (50 microM), adenosine caused a small and transient inhibition of glucose-induced electrical activity and insulin release. L-PIA (10 microM) slightly and transiently inhibited insulin release, 45Ca efflux and 86Rb efflux from islet cells, and decreased electrical activity in beta-cells. When adenylate cyclase was stimulated by forskolin in the presence of 15 mM glucose, insulin release was strongly augmented. Under these conditions, L-PIA and adenosine (with nitrobenzylthioguanosine) caused a sustained inhibition. No such inhibition was observed when insulin release was potentiated by dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP). These data are consistent with the existence of A1 purinergic receptors on mouse beta-cells. They could mainly serve to attenuate the amplification of insulin release brought about by agents acting via cAMP.

[Experimental study of Vicryl used as a filling material. Preliminary note]

The combination VICRYL and bone wax is studied as filling material in periodontal locations in dogs. Histological studies were carried out at one, two, six and nine months. Bone formation is already quite marked at two months, and total at six months. A desmodont and a secondary cement are formed. At six and nine month, reattachment is excellent.

Comparison of the inhibition of insulin release by activation of adenosine and alpha 2-adrenergic receptors in rat beta-cells

Rat islets were used to compare the mechanisms whereby adenosine and adrenaline inhibit insulin release. Adenosine (1 microM-2.5 mM) and its analogue N6(-)-phenylisopropyladenosine (L-PIA) (1 nM-10 microM) caused a concentration-dependent but incomplete (45-60%) inhibition of glucose-stimulated release. L-PIA was more potent than D-PIA [the N6(+) analogue], but much less than adrenaline, which caused nearly complete inhibition (85% at 0.1 microM). 8-Phenyltheophylline prevented the inhibitory effect of L-PIA and 50 microM-adenosine, but not that of 500 microM-adenosine or of adrenaline. In contrast, yohimbine selectively prevented the inhibition by adrenaline. Adenosine and L-PIA thus appear to exert their effects by activating membrane A1 receptors, whereas adrenaline acts on alpha 2-adrenergic receptors. Adenosine, L-PIA and adrenaline slightly inhibited 45Ca2+ efflux, 86Rb+ efflux and 45Ca2+ influx in glucose-stimulated islets. The inhibition of insulin release by adenosine or L-PIA was totally prevented by dibutyryl cyclic AMP, but was only attenuated when adenylate cyclase was activated by forskolin or when protein kinase C was stimulated by a phorbol ester. Adrenaline, on the other hand, inhibited release under these conditions. It is concluded that inhibition of adenylate cyclase, rather than direct changes in membrane K+ and Ca2+ permeabilities, underlies the inhibition of insulin release induced by activation of A1-receptors. The more complete inhibition mediated by alpha 2-adrenergic receptors appears to result from a second mechanism not triggered by adenosine.

An A2-purinoceptor agonist, NECA, potentiates acetylcholine-induced glucagon secretion

The effect of a stable structural analogue of adenosine, 5'-N-ethylcarboxamidoadenosine (NECA), was studied on glucagon secretion induced by acetylcholine (ACh) in the isolated perfused pancreas of the newborn dog. The perfusion solution contained a physiological concentration of glucose (4.2 mM). In the first set of experiments, ACh (0.5 microM) infused alone for 10 min induced a significant rise of glucagon secretion (370 +/- 98%, 4 min after the beginning of infusion). In the second set, NECA (2.2 nM) infused 10 min before ACh administration, had no effect per se, but considerably increased the response to ACh (929 +/- 262% of basal value within 3 min). So, the more specific A2 purinoceptor agonist, NECA, potentiated glucagon secretion induced by the cholinoceptor agonist, ACh.

Effects of 2-methylthio ATP on insulin secretion in the dog in vivo

The effects of 2-methylthio ATP, an ATP analogue that is more specific for the P2Y receptor, were investigated on insulin secretion in the anesthetized dog in vivo. 2-Methylthio ATP was infused directly into the pancreaticoduodenal artery for 15 min. The infusion was performed so as to obtain a pancreaticoduodenal artery blood level of about 15 microM. 2-Methylthio ATP induced an immediate and significant stimulation of insulin secretion measured from the pancreaticoduodenal vein by means of a T-shaped catheter. After the infusion was stopped, the secretion of insulin progressively decreased and at 30 min was close to basal values. The stimulation of insulin secretion induced a transient but significant reduction of peripheral venous blood glucose levels.

Cavernous hemangiomas of the spinal cord: MR imaging

In three patients with histologically proved cavernous hemangiomas of the spinal cord, magnetic resonance (MR) imaging was superior to myelography, delayed computed tomography (CT) myelography, and contrast-enhanced CT in depicting the lesion. The presence of mixed subacute and chronic hemorrhage, suggested by mixed high- and low-signal-intensity components of these lesions on MR images, may be characteristic of this rare, intramedullary vascular malformation.

Cavernous angiomas of the spinal cord

Five cases of histologically verified cavernous angiomas of the spinal cord are reported. Acute lower-extremity sensory disturbance was the initial symptom in four patients, and one presented with weakness of the hand. Progressive neurological deficit occurred in all patients, but the clinical course and outcome were extremely variable. Myelography revealed an intramedullary lesion in two cases but was completely normal in three; magnetic resonance imaging was diagnostic in these patients. Subtotal removal was accomplished in two cases, and myelotomy and biopsy were carried out in three. Four of the cavernous angiomas were located in the cervicothoracic region, whereas one was found in the thoracolumbar cord. All of the patients exhibited characteristic gross and microscopic features as well as hemosiderin-laden macrophages indicating remote hemorrhage. The diagnostic, therapeutic, and prognostic implications of this rare condition are discussed.

Diagnostic potential of magnetic resonance in cases of foramen magnum meningiomas

Meningioma is a histologically benign tumor that is second in frequency only to gliomas among primary intracranial tumors. Its extracerebral development and generally clear demarcation from the brain does not make it easier to detect on magnetic resonance (MR) scanning. Only 2 to 3% of meningiomas occur in the foramen magnum, and these tumors are often clinically misdiagnosed. We discuss four cases of foramen magnum meningioma, with emphasis on MR scanning.

Alpha 2-adrenergic potentiation of adenosine-stimulating effect on glucagon secretion

Previous studies from our laboratory showed 1) that adenosine (1.65 microM), a substance released by tissues in energy-deficient states, stimulated glucagon secretion by activation of A2 purinergic receptors, and 2) that this effect was potentiated by a low substimulating concentration of epinephrine through activation of alpha-adrenergic receptors. The present work was undertaken to assess the subtype of alpha-adrenergic receptor involved in this potentiation. Therefore, we used adrenergic blockers and agonist drugs more specific for alpha 1- or alpha 2-adrenergic receptors. The potentiating effect of epinephrine (0.01 microM) on glucagon secretion induced by adenosine (1.65 microM) was not prevented by an alpha 1-adrenergic blocker, prazosine (6 microM), but was suppressed by an alpha 2-adrenergic blocker, yohimbine (0.6 microM). The implication of alpha 2-adrenergic receptors in the potentiating effect was confirmed by the use of selective alpha 1- or alpha 2-adrenergic agonist drugs. Indeed, clonidine (0.01 microM), an alpha 2-agonist, ineffective per se, potentiated, whereas phenylephrine (0.01 microM), an alpha 1-agonist, had no effect on glucagon secretion induced by adenosine. We conclude that the potentiation by epinephrine of adenosine-induced glucagon secretion is mediated by alpha 2-adrenergic receptor activation. A potentiation between the effects of A2 purinergic and alpha 2-adrenergic agonists may be of physiological relevance in stressful energy-deficient states, when an increase in glucagon secretion is necessary.

Evidence for two different P2-purinoceptors on beta cell and pancreatic vascular bed

1 The effects of a 2-substituted analogue of adenosine 5'-triphosphate (ATP), 2-methylthioadenosine triphosphate (2-methylthio ATP) have been studied on insulin secretion and flow rate of the isolated pancreas of the rat, perfused in the presence of glucose (8.3 mM). 2 2-Methylthio ATP (16.5-1650 nM) increased insulin secretion in a biphasic and concentration-dependent manner; the kinetics were comparable to those previously obtained with ATP. A comparison of relative potency between ATP and 2-methylthio ATP showed that 2-methylthio ATP was 45 times more potent than ATP. 3 2-Methylthio ATP also provoked a transient decrease of the flow rate in a concentration-dependent manner but at concentrations (165-825 microM) about 1000 fold higher than those needed to increase insulin secretion. A comparison of relative potency between the natural derivative and 2-methylthio ATP showed that 2-methylthio ATP was only twice as potent as ATP. 4 These and other previous results (with phosphate-modified analogues of ATP) provide evidence for two different types of P2-purinoceptors on endocrine cell and vessel cells of the pancreas. A P2Y subtype, mediating an increase of insulin secretion, is present on the beta cell of the pancreas. A P2X subtype, mediating vasoconstriction, is present on the vascular bed of the rat pancreas.

Flow cytometric studies of colorectal tumors using fine needle aspiration

The results are reported of cytofluorometric DNA analyses of colorectal tumors using cells obtained by mechanical disruption and fine needle aspiration. The latter method does not lower the level of debris or cell aggregates. We found a significantly higher proportion of aneuploid cells by needle aspiration. There was a good correlation between the data obtained by both methods, but for large heterogeneous tumors multiple site aspirations are needed to obtain representative specimens. Fine needle aspiration was found particularly useful for small tumors and polyps.

Choroid plexus papilloma: magnetic resonance, computed tomography, and angiographic observations

Choroid plexus papillomas are rare intracranial neoplasms that are generally benign in nature. They are seen in both children and adults and have a male preponderance. Magnetic resonance imaging, a noninvasive diagnostic tool, demonstrated the intraventricular location and the surrounding anatomy with striking clarity, more effectively than angiography and computed tomography scanning.

Evidence for an inhibitory A1 subtype adenosine receptor on pancreatic insulin-secreting cells

The effects of L- and D-phenylisopropyladenosine (L- and D-PIA) were studied on glucose-induced insulin secretion from the isolated perfused rat pancreas. L-PIA at the low dose of 16.5 nM inhibited insulin secretion by 50%. In contrast, D-PIA at 16.5 and 82.5 nM was ineffective. D-PIA used at a 100-fold higher concentration (1.65 microM) than L-PIA induced a similar inhibition of insulin secretion. The inhibitory effect of L-PIA was abolished by 8-phenyltheophylline (1 microM), a potent P1 purinoceptor antagonist. The present experiments provide evidence for an adenosine receptor of the A1 subtype on the insulin-secreting pancreatic cell of rats.

Syringomyelia as a complication of Paget's disease. Case report

Cranial settling and basilar invagination with medullospinal compression is believed to have resulted in the production of a syrinx in a case of Paget's disease of the cranium. This mechanism of compression at the craniovertebral junction resembles the development of syringomyelia in Chiari malformations presenting in adult life.

Epinephrine potentiates adenosine-stimulating effect on glucagon secretion

The aim of the present work is to investigate a possible interaction on glucagon secretion between adenosine, a compound released by tissues in energy-deficient states, and epinephrine, the hormone of stress largely implicated in such conditions. The study was performed using the isolated perfused rat pancreas in presence of a physiological glucose concentration (5 mM). Epinephrine administered at a low concentration (0.01 microM) was ineffective on glucagon secretion, and adenosine at 1.65 microM was previously shown to be moderately stimulating. This nucleoside alone induced a transient increase of glucagon secretion rate that peaked at 300% of basal value at 2 min; in presence of epinephrine (ineffective per se) the rise induced by the nucleoside alone was doubled. This potentiating effect was not observed with the neurotransmitter norepinephrine at the dose tested. Propranolol (1 microM) did not alter the potentiating effect of epinephrine but this effect was completely suppressed by the alpha-blocker, phenoxybenzamine (6 microM). In conclusion epinephrine potentiates an adenosine-stimulating effect on glucagon secretion; this effect seems more specific for the adrenal medulla hormone epinephrine, since norepinephrine at the same dose is ineffective; it is mediated via alpha-adrenergic receptors. It is attractive to speculate that epinephrine and adenosine act in potentiating synergism on glucagon secretion; this might be of physiological importance during stressful energy-deficient situations.

[Integration of digital angiography, magnetic resonance, x-ray computed tomography and positron emission tomography in stereotaxy]

Consecutively to drastic changes which occurred in cerebral imagery techniques, we have developed a stereotactic apparatus and system based on the integration of several new techniques allowing visualisation of the brain: tomodensitometry (TDM), digital subtraction angiography (DSA), magnetic resonance (MR) and positron emission tomography (PET). TDM, DSA and MR can be performed in stereotactic conditions with the apparatus in situ. They give the computer the anatomic references necessary for all calculations. MR and PET images obtained without stereotactic apparatus can also be integrated into the stereotactic study at the condition that DSA was formerly performed in stereotactic conditions, i.e. with the apparatus in situ. The visualisation of the corpus callosum makes this integration possible. An optimal definition of cerebral tumors or target-structures for intracerebral electrode recording is thus obtained.

Combined use of digital subtraction angiography and MRI for radiosurgery and stereoencephalography

The authors report their experience with the combined use of digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) for the stereotactic placement of intracerebral electrodes in epilepsy and for the radiosurgical treatment of otherwise inoperable arteriovenous malformations of the brain. Both imaging techniques, when used in conjunction, have been found most useful and complementary. For deep electrode placement, they permit optimal visualization of the cerebral structures to be reached by the electrode array while allowing the avoidance of vessels in the vicinity. For radiosurgery of arteriovenous malformations, DSA provides optimal visualization of the feeders and of the malformation itself, while the MRI reveals the cerebral structures to be spared by the photon beam of the linear accelerator. A discussion of their respective roles is presented, with the specific question as to whether MRI alone could be used for both procedures.