Mutations of the ret protooncogene in German multiple endocrine neoplasia families: relation between genotype and phenotype. German Medullary Thyroid Carcinoma Study Group

It has been suggested that not only the position but also the nature of the mutations of the ret protooncogene strongly correlate with the clinical manifestation of the multiple endocrine neoplasm type 2 (MEN 2) syndrome. In particular, individuals with a Cys634-Arg substitution should have a greater risk of developing parathyroid disease. We, therefore, analyzed 94 unrelated families from Germany with inherited medullary thyroid carcinoma (MTC) for mutation of the ret protooncogene. In all but 1 of 59 families with MEN 2A, germline mutations in the extracellular domain of the ret protein were found. Some 81% of the MEN 2A mutations affected codon 634. Phenotype-genotype correlations suggested that the prevalence of pheochromocytoma and hyperparathyroidism is significantly higher in families with codon 634 mutations, but there was no correlation with the nature of the mutation. In all but 1 of 27 familial MTC (FMTC) families, mutations were detected in 1 of 4 cysteines in the extracellular domain of the ret protooncogene. Half of the FMTC mutations affected codon 634. Mutations outside of codon 634 occurred more often in FMTC families than in MEN 2A families. In all but 1 of 8 MEN 2B patients, de novo mutations in codon 918 were found. These data confirm the preferential localization of MEN 2-associated mutations and the correlation between disease phenotype and the position of the ret mutation, but there was no correlation between the occurrence of hyperparathyroidism or pheochromocytoma and the nature of the mutation.

Long-term treatment of acromegalic patients with repeatable parenteral depot-bromocriptine

We studied the efficacy and tolerability of a repeatable long-acting parenteral depot-bromocriptine preparation (Parlodel LAR) in 14 acromegalic patients, 10 of whom had received oral bromocriptine therapy previously, 2 of them showing intolerance to oral bromocriptine. Patients received i.m. injections of 50-100 mg depot-bromocriptine at 4-week intervals for 3-24 months (median 6). Growth hormone profiles were assessed by four daily samples at 4-week intervals. Main daily growth hormone levels decreased from 52.1 +/- 12.3 micrograms/l (mean +/- SEM) to 19.4 +/- 4.7 micrograms/l on the day of injection. In 6 patients, growth hormone values were lowered by more than 50%, whereas IGF-I levels decreased only slightly and growth hormone values during the oral glucose tolerance test remained non-suppressible. Tumour sizes were not affected. Two women became pregnant and were delivered of healthy babies. Side-effects typical of bromocriptine occurred frequently on the days of injection and diminished in most patients after 2 months of therapy despite increasing dosage. Compared with previous oral bromocriptine therapy, 9 of 10 patients preferred the depot preparation, whereas the reduction of growth hormone levels was similar during both treatments. In conclusion, depot-bromocriptine should be considered for acromegalic patients intolerant to oral bromocriptine.

Control of prolactin-secreting macroadenomas with parenteral, long-acting bromocriptine in 30 patients treated for up to 3 years

OBJECTIVE

We investigated the effect of intramuscular injections of long-acting bromocriptine in patients with macroadenomas.

STUDY DESIGN AND PATIENTS

Thirty patients with PRL-secreting pituitary macroadenomas were treated with repeated 4-weekly intramuscular injections of 50 or 100 mg of a long-acting, repeatable bromocriptine formulation for six to 37 injections, amounting to a total of 473 injections. Twenty patients received parenteral bromocriptine as primary therapy, ten had persisting hyperprolactinemia after previous therapies including pituitary surgery (n = 7), oral bromocriptine (7), and pituitary irradiation (2).

MEASUREMENTS

A PRL day profile was obtained and the patients' clinical status and history were documented, at intervals. Detailed clinical, laboratory, and radiological (pituitary nuclear magnetic resonance or computed tomography scan) evaluations were performed at baseline, after 1 injection and every 6th injection thereafter.

RESULTS

In all patients PRL was suppressed from a mean +/- SEM pretreatment level of 32,620 +/- 8680 to 4480 +/- 1140 mU/I on the third day after the first injection. In 12 patients PRL levels normalized (< 400 mU/I) with the first to fourth injection, in three additional patients PRL levels normalized after 8-15 months. In 19 patients PRL was suppressed to less than 1000 mU/l. In three patients PRL did not decrease to less than 50% of pretreatment; in two of them on oral bromocriptine prior to this study there had been a comparable low efficacy. Of 28 patients with macroadenomas (median height 22 mm) tumour shrinkage was evident in 15 by nuclear magnetic resonance or computed tomography scan 28 days after the first injection, and in three additional patients after 6 months. There was further regression in seven cases after 12, 18 or 24 injections. Adenoma size (mean +/- SEM) decreased to 66 +/- 7% of the pretreatment value. The 40 adverse events noted in 20 of 30 patients during 24 hours after the first injection were similar to known side-effects of oral bromocriptine, nausea and postural hypotension being the most frequent. With repeated injections, on average 0.6 adverse events were noted per injection (mostly mild asthenia). There were no local adverse reactions at the injection site.

CONCLUSION

We conclude that long-acting repeatable bromocriptine in patients with macroprolactinomas offers a safe and efficacious primary treatment that ensures compliance and gives long-term control. Adverse reactions are comparable to oral bromocriptine but subside with repeated injections.

Basophilic leukocytes in hypothyroidism

Since in the literature basophilia is frequently related to myxedema, we evaluated basophilic leukocytes in patients with hypothyroidism, applying routine techniques used in clinical laboratories. The study included normal persons, untreated patients with hypothyroidism, and euthyroid subjects with hyperlipidemia. The number of circulating basophils was determined by differential counts of Pappenheim stained blood smears. No difference in relative and total basophil counts was detected in patients with hypothyroidism as compared to healthy controls (1.0% and 58.1 basophils/microliters vs. 0.8% and 50.8 basophils/microliters, respectively). The percentage of basophils in myxedema associated with hypercholesterolemia amounted to 1.0%, their absolute number to 57.6/microliters; in hypothyroid patients presenting normal serum cholesterol levels, the relative and absolute numbers of basophilic leukocytes was not statistically different (0.83% and 61.1 basophils/microliters, respectively). We conclude that in patients with hypothyroidism the number of basophils is not statistically different from the values of basophils in healthy controls. Furthermore, the number of peripheral blood basophils in hypothyroidism is not related to the serum cholesterol level.

The phospholipid analogue, hexadecylphosphocholine, inhibits protein kinase C in vitro and antagonises phorbol ester-stimulated cell proliferation

The antineoplastic agent, hexadecylphosphocholine, a phospholipid analogue, inhibited phosphatidylserine-activated protein kinase C in vitro at concentrations higher than 40 mumol/l. The half-inhibitory concentration (IC50) was 62 mumol/l. Another alkylphosphocholine, dodecylphosphocholine, did not have an inhibitory effect on protein kinase C. At the same concentrations, hexadecylphosphocholine antagonised the phorbol ester-stimulated proliferation of Madin-Darby canine kidney cells whereas dodecylphosphocholine had no effect. In addition, phorbol ester-induced morphological changes of these epithelial cells were antagonised by hexadecylphosphocholine. Both effects of hexadecylphosphocholine, the inhibition of protein kinase C and the antagonisation of the altered cell morphology induced by phorbol ester, were comparable to those observed after treatment with sphingosine, a known protein kinase C inhibitor. We conclude that one possible mechanism of the antineoplastic action of hexadecylphosphocholine is mediated by inhibition of protein kinase C.

The phospholipid analogue hexadecylphosphocholine inhibits phosphatidylcholine biosynthesis in Madin-Darby canine kidney cells

The influence of the phospholipid analogue hexadecylphosphocholine on phosphatidylcholine biosynthesis was investigated in Madin-Darby canine kidney (MDCK) cells. It inhibits the incorporation rate of [methyl-3H]choline into phosphatidylcholine at a concentration of 50 microM by about 50%. The radiolabelled precursor accumulates in the phosphocholine pool indicating that hexadecylphosphocholine inhibits the formation of phosphatidylcholine via the CDP-choline pathway at the level of the rate-limiting enzyme. CTP:phosphocholine cytidylyl transferase (EC 2.7.7.15). This was verified by the determination of the activity of the enzyme in vitro. In consequence of its inhibitory effect it could be shown that the treatment of MDGK cells for 24 h with 50 microM hexadecylphosphocholine induces alterations of the phospholipid composition. Whereas in treated cells the relative phosphatidylcholine content was decreased from the control level of 36.0 +/- 0.9% to 29.9 +/- 0.2%; in contrast, the relative content of phosphatidylethanolamine was increased from 19.3 +/- 0.9% to 24.3 +/- 0.9%.

Analysis of human apolipoproteins C by isoelectric focusing in immobilized pH gradients

Apolipoproteins C are involved in many ways in the metabolism of plasma lipoproteins. Apolipoproteins C from the delipidated VLDL of 35 controls and 165 normo- and hyperlipoproteinemic patients were analyzed by isoelectric focusing on an immobilized pH gradient, pH 4.0-5.0, with 7 M urea, which raised the apparent pH range to 4.8-5.7. This method is an improvement over conventional isoelectric focusing with carrier ampholytes with regard to both resolution and reproducibility. Due to the high resolution (0.1 pH units per cm) additional apolipoprotein C-III bands: C-III0 A1, C-III0 A2, C-III1 C and C-III2 C (the designations A, anodic, and C, cathodic, refer to direction of migration on IEF in relation to the main band) are described for the first time. The possible artifactual nature of these protein bands could be excluded. Cleavage with neuraminidase and peptidases, immunological detection and/or two-dimensional electrophoresis were used to obtain more information. The additional bands seem, in part, to be hydrolysis products of carboxypeptidase A (C-III1 C, C-III2 C). The appearance of C-III1 C and C-III2C was dependent upon the serum triglyceride concentration. The percent distribution of C apolipoproteins in very low density lipoproteins (VLDL) from control serum agreed with previously published data. Apolipoproteins C can also be focused in immobilized pH gradients from VLDL and serum without delipidation.

Mitochondrial and cytosolic ATP/ADP ratios in isolated hepatocytes. A comparison of the digitonin method and the non-aqueous fractionation procedure

The ratio of ATP content/ADP content in the mitochondrial matrix was found to be 2.07 +/- 0.21 and 2.26 +/- 0.22 as determined with six different preparations of isolated hepatocytes subfractionated with the digitonin and non-aqueous-fractionation procedures, respectively. In contrast, the mitochondrial matrix ATP/ADP determined with isolated haemoglobin-free perfused liver by using the non-aqueous-fractionation procedure was about 0.2, whereas the cytosolic values obtained with isolated cells and with the intact organ were similar. It is concluded that the relatively higher ATP/ADP ratio in the mitochondrial matrix of isolated hepatocytes represents a biochemical difference due to properties of the model rather than a methodological artifact.

Thermodiffusion im kritischen Verdampfungsgebiet binärer Systeme

Es werden Messungen des Thermodiffusionsfaktors für das fluide System Methan + Propan beschrieben und diskutiert. Dabei liegt der Druck zwischen 40 und 75 bar, die mittlere Temperatur bei rund 73 °C, der mittlere Molenbruch des Methans zwischen 0,23 und 0,63. Das System befindet sich in der Nähe eines kritischen Verdampfungspunktes, und zwar teils im Gaszustand, teils im hyperkritischen Gebiet. Die Prüfung eines auf Plausibilitätsbetrachtungen beruhenden Ansatzes für den Thermodiffussionsfaktor bei fluiden Zweistoffsystemen (Haase 1950) führt zu einem qualitativ befriedigenden Bild. Insbesondere ist die Aussage, daß der Thermodiffusionsfaktor bei Annäherung an einen kritischen Punkt unendlich wird, mit den Messungen am vorliegenden System und auch an anderen binären fluiden Systemen verträglich.

Thermoosmose in Flüssigkeiten

Neue Messungen am System Cellophan (600) + Wasser im Temperaturbereich zwischen 10 °C und 90 °C werden mitgeteilt und diskutiert. Es handelt sich um die Permeabilität, die Überführungswärme und die thermoosmotische Permeabilität, die für Permeation und Thermoosmose maßgebend sind, sowie um die Temperaturabhängigkeit des Wassergehaltes der Folie bei Quellungsgleichgewicht. Es wird untersucht, ob Cellophanfolien in flüssigem Wasser als Porenmembranen bzw. als Löslichkeitsmembranen anzusehen sind. Besondere Aufmerksamkeit wird der Richtungsumkehr der Thermoosmose bei einer mittleren Temperatur von etwa 56 °C gewidmet