Lars-Ove Farnebo

HRPT2, encoding parafibromin, is mutated in hyperparathyroidism-jaw tumor syndrome.

We report here the identification of a gene associated with the hyperparathyroidism–jaw tumor (HPT–JT) syndrome. A single locus associated with HPT–JT (HRPT2) was previously mapped to chromosomal region 1q25–q32. We refined this region to a critical interval of 12 cM by genotyping in 26 affected kindreds. Using a positional candidate approach, we identified thirteen different heterozygous, germline, inactivating mutations in a single gene in fourteen families with HPT–JT. The proposed role of HRPT2 as a tumor suppressor was supported by mutation screening in 48 parathyroid adenomas with cystic features, which identified three somatic inactivating mutations, all located in exon 1. None of these mutations were detected in normal controls, and all were predicted to cause deficient or impaired protein function. HRPT2 is a ubiquitously expressed, evolutionarily conserved gene encoding a predicted protein of 531 amino acids, for which we propose the name parafibromin. Our findings suggest that HRPT2 is a tumor-suppressor gene, the inactivation of which is directly involved in predisposition to HPT–JT and in development of some sporadic parathyroid tumors.

A sensitive method for the determination of plasma catecholamines using liquid chromatography with electrochemical detection

Abstract Simple and sensitive methods for the determination of plasma catecholamines are of great interest since the level of catecholamines in plasma reflects the activity of the sympatho-adrenal system. In the present work a previously described procedure based on high pressure liquid chromatography with electrochemical detection has been adapted for assay of plasma catecholamines. This method permits simultaneous detection of noradrenaline, adrenaline and dopamine in concentrations down to 0.1 nmol/1 in less than one ml plasma.

Effect of prostaglandin E2 on central and peripheral catecholamine neurons

Abstract Effects of prostaglandin E2 (PGE2) on catecholamine (CA) release from CA neurons have been studied in two models; influence on field stimulation-induced overflow of tritium from isolated tissues pre-incubated with 3H-CA; influence on dopamine (DA) disappearance in the neostriatum induced by tyrosine hydroxylase inhibition utilizing histochemical fluorescence analysis of catecholamines. In vitro PGE2 (3 × 10−6 M) caused a small but probably significant reduction of the field stimulation-induced tritium overflow from central noradrenaline (NA) and central DA nerve terminals and a significant reduction of the stimulation-induced overflow from peripheral NA nerve terminals. In the in vivo experiments PGE2 in μg amounts was dissolved in Krebs-Ringer bicarbonate buffer and infused into the left neostriatum, whereas buffer alone was infused into the right neostriatum. Infusion of 9–18 μg of PGE2 reduced the disappearance of DA fluorescence after treatment with the tyrosine hydroxylase inhibitor α-methyl-tyrosine methylester ( H 44 68 ) under resting conditions, but could not counteract the increase in H 44 68 - induced DA disappearance caused by electrical stimulation of the nigro-neostriatal DA pathway. The findings suggest that PGE2 can modify but not stop the release of DA and NA from central CA nerve terminals and indicate that prostaglandins might act as modulators of central CA neurotransmission.

Dopamine and noradrenaline releasing action of amantadine in the central and peripheral nervous system: A possible mode of action in Parkinson's disease

Abstract Histochemical, biochemical and functional analyses of the effects of amantadine on the monoamine neurons in the peripheral and central nervous system of rat after various pretreatments have shown that amantadine, both in vivo and in vitro, is capable of releasing DA and NA from extragranular stores in central DA and NA neurons and in peripheral NA neurons. The functional findings on rotational behaviour, reflex activity and locomotor behaviour show that the increased release of DA and NA induced by amantadine in the brain also results in increased DA and NA receptor activity. Thus, both from a chemical and functional viewpoint amantadine has an amphetamine-like action. The potency of amantadine, however, is weak compared to that of amphetamine. A direct action on DA receptors can be excluded, since presynaptic stores of CA are required for amantadine to increase CA receptor activity.

Patterns of Chromosomal Imbalances in Parathyroid Carcinomas

In this study we have characterized chromosomal imbalances in a panel of 29 parathyroid carcinomas using comparative genomic hybridization (CGH). The most frequently detected imbalances were losses of 1p and 13q that were seen in >40% of the cases. The commonly occurring regions of loss were assigned to 1p21-p22 (41%), 13q14-q31 (41%), 9p21-pter (28%), 6q22-q24 (24%), and 4q24 (21%), whereas gains preferentially involved 19p (45%), Xc-q13 (28%), 9q33-qter (24%), 1q31-q32 (21%) and 16p (21%). The distribution of CGH alterations supports the idea of a progression of genetic events in the development of parathyroid carcinoma, where gains of Xq and 1q would represent relatively early events that are followed by loss of 13q, 9p, and 1p, and by gain of 19p. A sex-dependent distribution was also evident for two of the common alterations with preferential gain of 1q in female cases and of Xq in male cases. When the CGH profiles for the 29 carcinomas were compared with our previously published results for sporadic parathyroid adenomas, highly significant differences were revealed. Loss of 1p, 4q, and 13q as well as gains of 1q, 9q, 16p, 19p and Xq were significantly more common in the carcinomas than in the adenomas. In contrast, loss of the 11q13 region, which is the most common CGH abnormality in sporadic adenomas, was not detected in any of the carcinomas. Taken together, the findings identify several candidate locations for tumor suppressor genes and oncogenes that are potentially involved in parathyroid carcinogenesis.

Differential loss of heterozygosity in familial, sporadic, and uremic hyperparathyroidism

Abstract Various genetic loci harboring oncogenes, tumor suppressor genes, and genes for calcium receptors have been implicated in the development of parathyroid tumors. We have carried out loss of heterozygosity (LOH) studies in chromosomes 1p, 1q, 3q, 6q, 11q, 13q, 15q, and X in a total of 89 benign parathyroid tumors. Of these, 28 were sporadic parathyroid adenomas from patients with no family history of the disease, 41 were secondary parathyroid tumors, 5 were from patients with a history of previous irradiation to the neck, 12 were from patients with a family history of hyperparathyroidism, and 3 were parathyroid tumors related to multiple endocrine neoplasia type 1 (MEN1). In addition, we determined the chromosomal localization of a second putative calcium-sensing receptor, CaS, for inclusion in the LOH studies. Based on analysis of somatic cell hybrids and fluorescent in situ hybridization to metaphase chromsomes, the gene for CaS was mapped to chromosomal region 2q21-q22. The following results were obtained from the LOH studies: (1) out of the 24 tumors that showed LOH, only 4 had more than one chromosomal region involved, (2) in the tumours from uremic patients, LOH of chromosome 3q was detected in a subset of the tumors, (3) LOH of the MEN1 region at 11q13 was the most common abnormality found in both MEN1-related and sporadic parathyroid tumours but was not a feature of the other forms of parathyroid tumors, (4) LOH in 1p and 6q was not as frequent as previously reported, and (5) tumor suppressor genes in 1q and X might have played a role, particularly on the X chromosome, in the case of familial parathyroid adenomas. We therefore conclude that the tumorigenesis of familial, sporadic, and uremic hyperparathyroidism involves different genetic triggers in a non-progressive pattern.

Effects of desipramine, phentolamine and phenoxybenzamine on the release of noradrenaline from isolated tissues

concentrated to give samples having >1.0 mg/ml protein. The fractions at the protein peak of each secretion were also combined and concentrated to give samples having similar concentrations of protein. The concentrated combined fractions were separately dialysed against 0 . 0 1 ~ sodium acetate buffer, pH 3.6 in 0 . 1 5 ~ NaCl and the interaction with sodium salicylate at a final concentration of 100 mM was measured turbidimetrically as described. The results are shown in Table 1. Neither the glycoprotein nor the protein fractions from either sample of posthistalog gastric juice interacted with sodium salicylate, confirming the observations with unfractionated post-histalog gastric juice. However, protein fractions of both resting gastric juice and saliva interacted strongly with sodium salicylate. There was also a very slight interaction with the glycoprotein fraction in both resting gastric juice and saliva. Although little precipitation of the separated glycoproteins of resting gastric juice or saliva was detected, it is possible that in the whole secretions there may be some coprecipitation of the glycoprotein during precipitation of the protein. However, to obtain any detectable precipitation of the protein from either gastric juice or saliva the secretion had to be concentrated at least 10 times, and even in the concentrated secretions, the maximum precipitation obtained represented less than 20% of the total protein and glycoprotein. Thus it seems unlikely that in man there would be any significant precipitation of glycoprotein of gastric juice by 100 mM sodium salicylate in vivo. This work was supported by the Asthma Foundation of Victoria and the National Health and Medical Research Council. The University of Melbourne Department of Medicine, The Royal Melbourne Hospital, Victoria 3050, Australia. July 8, 1970

Histochemical studies on the uptake of noradrenaline and α-methyl-noradrenaline in the perfused rat heart

Abstract The cellular localization of noradrenaline and α-methyl-noradrenaline taken up by the rat isolated heart during perfusion was studied. After perfusion with low concentrations, 0.02–0.2 μg/ml, uptake of the catecholamines into the adrenergic nerves occurred but no evidence for an extraneuronal uptake was found. After perfusion with high concentrations, 5–20 μg/ml, there was a markedly increased flourescencein the heart muscle cells. In the atria numerous small intensely fluorescent connective tissue cells could be found. In both cases the fluorescence proved to be due to the presence of catecholamines. The extraneuronal uptake could be inhibited by normetanephrine but not desipramine. It is concluded that the catecholamines taken up in the rat heart during perfusion with high concentrations are located partly in the adrenenic nerves but also to a great extent extraneuronally.

Brain tissue transplanted to the anterior chamber of the eye

SummarySmall pieces of fetal rat brain selected to contain a high number of noradrenaline (NA), dopamine (DA), or 5-hydroxytryptamine (5-HT) neuroblasts were transplanted to the anterior chamber of the eye of adult rats. The sympathetic ground plexus of the host iris was removed by superior cervical ganglionectomy so that transmitter mechanisms of the different central monoamine fibers innervating the iris could be selectively studied after intraocular maturation. Such irides, containing NA, DA, or 5-HT nerve terminals were incubated with radiolabelled transmitters and then stimulated by an electrical field while superfused, to investigate the spontaneous and stimulation-induced release of amine, both in drug-free buffer and buffer containing drugs acting on monoamine receptors.The central monoamine neurons of all three types were able to take up exogenous amines and release them upon stimulation by an electrical field, in much the same way as corresponding nerves in situ in slices of cerebral cortex (NA, 5-HT) or olfactory tubercle (DA).The α-adrenergic receptor blocking agent phentolamine increased the stimulation-induced release of 3H-NA from central NA fibers on the iris significantly. The dopamine receptor stimulating agent apomorphine decreased the stimulation-induced release of 3H-DA from central DA fibers on the iris. Pimozide, a DA receptor blocking drug tended to increase the 3H-DA release. The 5-HT receptor stimulating agent ergocornine tended to reduce the stimulation-induced release of 3H-5-HT from central 5-HT fibers on the iris. It was concluded that all three types of central monoamine nerve fibers develop essentially normal transmitter storage and release mechanisms also in an environment completely devoid of normal postsynaptic receptors. The drug experiments add strong support to the view that there are presynaptic monoamine receptors (“autoreceptors”) able to modulate transmitter release present on the monoamine nerve terminals.

Effect of some antiparkinsonian drugs on catecholamine neurons

The inhibitory effect of some antiparkinsonian drugs on the accumulation of catecholamines into rat dopamine and noradrenaline neurons was studied with isotope and histochemical fluorescence methods in vivo and in vitro. Benztropine was the most potent drug hitherto tested to inhibit accumulation of catecholamines into dopamine neurons and was effective down to a dose of 10mg/kg. Also ethybenztropine, brompheniramine, diphenylpyraline, chlorpheniramine and methixene, in doses of 50 mg/kg, inhibited accumulation of catecholamines. Atropine, scopolamine, benzhexol, diphenhydramine and many other antiparkinsonian agents were ineffective.