Treatment of prolactinoma patients with the new non-ergot dopamine agonist roxindol: first results

We studied the effects of the new non-ergot D₂-dopamine agonist roxindol for the treatment of human prolactinomas. Roxindol is a non-ergot drug with additional 5-hydroxytryptamine type 1 A agonist and serotonin reuptake inhibitory activity. Ten patients with prolactin-secreting pituitary adenomas received roxindol three times daily at a dosage of 7.5–30 mg/day for at least 4 weeks according to a prospective protocol. All patients but one had received oral bromocriptine previously without normalization of prolactin levels. Serum prolactin profiles were analyzed once a week during the first month of therapy and at 4-week intervals thereafter. Mean baseline serum prolactin was suppressed from 23000±13 600 mU/1 (range 1500–141000 mU/1; 20 mU/l=1 g/1) by 37 ± 11 % after 1 week, by 49±9% after 4 weeks, and by 65±11% (n = 8) after 24 weeks of treatment. Serum prolactin was normalized in two patients. A tumor volume reduction of 20–25% was obtained in two subjects. Compared with previous treatment with oral bromocriptine the decrease in serum prolactin was comparable. In contrast, tolerance of roxindol was superior in five of seven patients with major side effects with bromocriptine, including three subjects who had discontinued bromocriptine because of adverse reactions. Four subjects spontaneously reported improvement of psychological and physical performance. One patient had a transient increase of serum transaminases. Thus, for the first time we could show a suppressive effect of roxindol on prolactin secretion in human prolactinomas. Due to its good tolerance roxindol may provide a useful alternative to bromocriptine.Abbreviations MRI magnetic resonance imaging - PRL prolactin Correspondence to: C. Jaspers     

Bromocriptine treatment over 12 years in acromegaly: effect on glucose tolerance and insulin secretion

Summary It is not known whether the beneficial effect of bromocriptine on glucose homeostasis in acromegaly is limited by a certain duration of therapy. To elucidate this problem, oral glucose tolerance tests were performed in 12 acromegaly patients before bromocriptine medication, under therapy (15.0 ± 6.8 mg/day for 12 ± 3 years), and during a 2-week drug withdrawal after long-term treatment. Initially altered glucose tolerance was normalized in 4 of 5 patients under bromocriptine therapy. During drug withdrawal the mean fasting glucose level and the mean glucose concentration at 120 min after oral glucose load increased from 5.05 ± 0.61 to 5.77 ± 0.78 mmol/1 and from 5.61 ±2.05 to 7.55 ± 3.05 mmol/1, respectively. A deterioration in glucose homeostasis was observed in 9 patients, and impaired glucose tolerance was ameliorated (but not to normal range) in 2 when bromocriptine was withdrawn. The proportion of alterations in glucose tolerance during drug withdrawal corresponded to that before the beginning of long-term bromocriptine treatment. Impaired glucose tolerance, observed in 2 patients under bromocriptine treatment, seemed to be compensated because a distinct elevation of glycosylated hemoglobin A_1c was not observed. Bromocriptine led to a significant decrease in basal as well as glucose-stimulated insulin levels, and growth hormone secretion during oral glucose load was reduced in all 12 patients. Similarly to the increased growth hormone secretion after drug withdrawal in 11 patients, a rise in glucose-stimulated insulin secretion was found in all patients; hereby, the mean insulin levels at 0 and 120 min during oral glucose load rose significantly from 7.5 ± 2.6 to 12.1 ± 5.1 mU/1 (P<0.01) and from 71.3±52.1 to 101.4±50.7 mU/1 (P<0.02), respectively. A direct relationship between disturbance in glucose homeostasis and degree of hypersomatotropism was not observed. Our data confirm that the beneficial effect of bromocriptine therapy on glucose homeostasis in selected patients with acromegaly is still present after dopaminergic treatment over a mean period of 12 years. Compared with the published rates on improved glucose homeostasis under octreotide, the effect of bromocriptine seems to be more favorable.Abbreviations AUC area under the curve - GH growth hormone - PRL prolactin Dedicated to Prof. Dr. N. Zöllner on the occasion of his 70th birthday     

Long-term treatment with SMS 201–995 in resistant acromegaly: Effectiveness of high doses and continuous subcutaneous infusion

Summary Seventeen patients (8 women and 9 men) resistant to all other forms of therapy were treated with the somatostatin analogue SMS 201-995 (octreotide, Sandostatin^®). The duration of treatment ranged from 1 to 5 years. Mean GH levels of only 4 patients were suppressed under 5 g/L during an 8 h serum profile with the standard dose of 0.1 mg 2 or 3 times daily. This standard dose suppressed mean GH levels in 10 other patients more than 50% of baseline, but for optimal effect higher doses up to 1.5 mg, 4 daily injections or continuous subcutaneous infusion (CSI) were needed. Octreotide had no influence on GH secretion in 3 patients. Suppression of mean GH levels under 5 g/L was achieved in 10 patients. Normalization of insulin-like growth factor I (IGF-I) occured in only 5 patients. Altogether, therapy with SMS 201-995 reduced GH levels from 23.8±32.2 g/L (mean±SD) to 6.7±5.0 g/L by 71.8% and IGF-I levels from 7.9±3.1 U/ml to 3.2±1.6 U/ml by 59.5%.We conclude that 1) treatment with SMS 201-995 in patients resistant to other forms of therapy may be less successful than previously reported for heterogenous groups of patients; 2) the dose regimen must be adapted to the individual patient for optimal effect and most of our patients needed higher doses than 300 g daily; 3) 4 or maybe more daily injections or CSI seem to be most effective; and 4) in a minority of patients SMS has no influence on GH-secretion.Abbreviations CSI continuous subcutaneous infusion - CT computerized tomography - GH growth hormone - IGF-I insulin-like growth factor I=Somatomedin-C - IRMA immunoradiometric assay - MRI magnetic resonance imaging - PRL prolactin - RIA radioimmunoassay - SD standard deviation - SMS octreotide=Sandostatin^® - TSH thyreoidea stimulating hormone - T4 thyroxine This work was supported by the Deutsche Forschungsgemeinschaft (Mue 585/3-3). Parts of this work were presented on the 34. Symposium Deutsche Gesellschaft für Endokrinologie Hannover, March 1990 (Acta Endocrinologica Suppl. 1 Vol. 122 (1990), 14)     

Transient improvement of polymorphonuclear leukocyte function by splenectomy in β-thalassemia

Host defense mechanisms in transfusion-dependent non-splenectomized patients with -thalassemia were studied. Polymorphonuclear leukocytes (PMNLs) of non-splenectomized patients responded poorly to zymosan generated chemotactic factors. Chemotactic indices were 22.1 m ± 2.8 (mean ± S.D.) using zymosan activated serum (ZAS) as the attractant in comparison to 20.4 m ± 2.6 when fresh untreated serum was used. In contrast, chemotactic indices of normal PMNLs increased from 21.1 m to 33.6 m ± 3.1 in response to ZAS. Normal PMNL responses to a mixture of normal ZAS and thalassemic serum were inhibited; the mean chemotactic index was 18.1 m ± 5.1 with use of ZAS alone. Splenectomy temporarily reverses these alterations. Adherence to nylon wool of PMNLs suspended in fresh thalassemic serum prior to splenectomy was 3.1% ± 1.1 (mean ± S.D.); 20 days after splenectomy adherence increased to 14.0% ± 2.8 (P = 0.0001) and remained at this level for 90 days. At 120 and 150 days after splenectomy adherence decreased to 1.5% ± 0.8 and 1.0% ± 0.85 respectively. Splenectomy also transiently abrogated the failure of zymosan to generate chemotactic factors in thalassemic serum.This study was presented in part at the American Federation for Clinical Research, Central Society, Infectious Diseases, Chicago, Illinois, November 3, 1983     

Study on growth hormone and insulin secretion in myotonic dystrophy

Growth hormone (GH) levels were measured in 12 patients with myotonic dystrophy (MD; 7 men and 5 women, aged 21–49 years) and 14 volunteers after administration of 100 g GH-releasing hormone (GHRH; 1–29). A 75-g oral glucose tolerance test was carried out to determine glucose, insulin, plasma C-peptide, and urinary C-peptide. The GH level in six MD patients responded normally to GHRH (group I), with a peak of 17.1 ± 1.46 g/l, compared withcontrols (27.8 ± 19.6 g/l, NS), and that in the other six patients responded subnormally, with a peak of 3.15 ± 1.46 g/l, lower than in controls and in group I patients (P < 0.001). In group I the insulin response to the glucose tolerance test showed hyperinsulinism and was lower than that in group II patients; stimulated C-peptide was also higher in group II than in group I and in controls; urinary C-peptide levels were parallel to those in previous data. In all MD patients there were a negative correlation between absolute values of GH response to GHRH and insulin response to glucose tolerance test (r = - 0.79, P < 0.001). Our data suggest that the failure in GH release and peripheral insulin action is due to a generalized defect in cellular membrane function in MD patients.Abbreviations BMI body mass index - GH Growth hormone - GHRH growth hormone releasing hormone - MD myotonic dystrophy Correspondence to: J. M. Gomez Saez     

Tubular transport processes in proximal tubules of hypothyroid rats. Lack of relationship between thyroidal dependent rise of isotonic fluid reabsorption and Na+−K+-ATPase activity

Hypothyroid rats reconstituted with 10 g/kg b.w. per day of tri-iodothironine (T₃) for 4 days resulted in normal free T₃ and TSH levels. FT₃ levels were: 0.53±0.3 pg/ml in hypothyroid rats; 2.78±1.21 pg/ml in hormone reconstituted rats and 2.90±0.90 pg/ml in euthyroid rats. TSH levels were 3,508±513 g/ml in hypothyroid rats; 1,008±204 g/ml in reconstituted rats and 270±184 ng/ml in euthyroid rats.When hypothyroid rats were reconstituted with 50 g T₃/kg b.w. per day, TSH levels were nearly normal after 4 days (1,157±621 ng/ml). However FT₃ levels after 1–4 days were always higher than in euthyroid rats.Hypothyroid rats show a decrease in isotonic fluid reabsorption (J _v) in the proximal tubule (1.50±0.08 versus 4.96±0.23 10^–2 nl·mm^–1·s^–1 in euthyroid animals). 1 day after T₃ (10 g/kg b.w./day) injectionJ _v was increased significantly to 2.05±0.20 10^–2 nl·mm^–1·s^–1 and continued to increase during 4 days of T₃ reconstitution.When 50 g T₃/kg b.w./day was used,J _v increased to 2.75±0.07 after 1 day and to 3.10±0.42 10^–2 nl·mm^–1·s^–1 after 4 days.J _v was never reaching a value close to that of euthyroid rats because the tubular radius in hypothyroid rats (14.7±1.8 m) is less than that of euthyroid rats (19.2±0.5 m). The radius in hypothyroid rats treated with T₃ was unchanged over a 4 day course with either high or low doses of T₃.Na⁺–K⁺-ATPase activity was found to be 2.91±0.16 M P_i/h×mg protein in homogenates of kidney cortex from hypothyroid rats. Treatment of hypothyroid rats with 10 g or 50 g of T₃ resulted in an initial decrease in ATPase activity, followed by an increase to base level in hypothyroid rats with 10 g and a significantly higher level with 50 g. This decrease in ATPase activity was contrasted to the increase inJ _v.These data indicate that there is a dissociation between the effects of physiological doses of thyroid hormones on proximal tubular reabsorption and the effects of T₃ on Na⁺–K⁺-ATPase activity of kidney cortex. This leads to question the relationship between sodium transport and ATPase activity under physiological doses of thyroid hormones. An early effect of physiological doses of thyroid hormones on brush border Na⁺ permeability is suggested.     

Calcium sensitivity and unloaded shortening velocity of hypertrophied and non-hypertrophied skinned human atrial fibres

The mechanical properties of myocardium of different animals are modified by a chronic increase in haemodynamic load. In this study differences in calcium sensitivity and maximum unloaded shortening velocity of hypertrophic and non-hypertrophic chemically skinned human atrial fibres are characterized. Investigating right atria of 34 patients, possible correlations are studied between preoperative atrial pressure, degree of hypertrophy (estimated from the muscle fibre diameter), calcium responsiveness (pCa₅₀ eliciting half-maximum contraction) and V _max (unloaded shortening velocity). Hypertrophic fibres from atrial appendages of patients having an increased right atrial pressure (RAP 8.5±1.6 mm Hg) and suffering from mitral valve disease (stenosis and insufficiency combined) had a fibre diameter of 18.0±0.9 m. They also had a higher calcium sensitivity (pCa₅₀ 5.65±0.08) and a lower unloaded shortening velocity (1.7±0.1 muscle lengths/s) than non-hypertrophic fibres from the appendages of patients with normal right atrial pressure (RAP 3.2±0.5 mm Hg) and coronary heart disease (CHD: pCa₅₀ 5.45±0.04; V _max= 3.4±0.2 muscle lengths/s; fibre diameter 12.8±0.4 m). Thus non-hypertrophic fibres from control CHD patients differed significantly (p < 0.01) from hypertrophied atrial fibres of patients with mitral valve disease and with combined valve disease (MAV, pCa₅₀=5.58±0.05, V _max 2.0±0.3 muscle lengths/s, fibre diameter 14.6±0.9 m) or aortic valve disease (stenosis combined with insufficiency, fibre diameter 14.8±1.4 m, pCa₅₀ 5.56±0.03, V _max 2.0±0.24 muscle lengths/s; RAP 11.0±2.6 mm Hg). Such alterations of calcium responsiveness, shortening velocity and fibre thickness may reflect an adaptation to the chronic overload in atria from patients with various forms of heart valve disease.     

Suppressed thyroid-stimulating hormone secretion in patients treated with interleukin-2 and interferon-α2b for metastatic melanoma

Recent reports suggest that combined therapy with recombinant interleukin (IL)-2 and interferon (IFN) alb may result in autoimmune-induced thyroid dysfunction. We prospectively analyzed thyroid function for 6 weeks in two groups of patients with progressive metastatic melanoma treated according to two different protocols. In group I (n =17) three treatment cycles were given, each with three weeks of subcutanous administration of rIL-2 and INF-_2b at different doses. In group 11 (n=13) the chemotherapeutic agent dacarbazine was given in addition. In group 1 three patients developed frank hyperthyroidism, which required antithyroid drug therapy in one case. Autoantibodies against thyroid microsomal antigen, thyroglobulin, and the thyroid-stimulating hormone (TSH) receptor were not significantly elevated in any of these patients. However, the remaining 14 patients showed a significant decrease in TSH after 6 weeks of treatment, from 1.8 ± 0.9 to 0.7 ± 0.7 U/ml (P < 0.02). Thyroid hormones (triiodothyronine, thyroxine, free thyroxine) also increased during the observation time, but this did not parallel the drop in TSH levels. Only thyroxine increased above the upper limit of normal, while triiodothyronine and free thyroxine stayed within the normal range. In group 11, 6 of 13 patients (46%) had a decreased TSH after 6 weeks of treatment. Mean TSH was 1.5±1.4 before and 0.8 ± 0.6 U/ml after 6 weeks and was totally suppressed in three cases. None of these patients showed ouvert hyperthyroidism. Hypothyroidism was not observed in either group. We conclude that treatment with rIL-2 and INF-_2b may not only be associated with autoimmune thyroiditis and hyperthyroidism but also results in suppression of TSH levels while the patients remain euthyroid.Abbreviations IL interleukin - INF interferon - TSH thyroid-stimulating hormone - T3 triiodothyronine - T₄ thyroxine - fro free thyroxine Correspondence to: H. Mönig     

Effects of atrial natriuretic factor on anterior pituitary hormone secretion in normal man

Summary The effects of intravenous human atrial natriuretic factor ANF(99-126) administration on anterior pituitary hormone secretion have not been extensively investigated in humans. We repeatedly studied 10 healthy volunteers (5 female, 5 male, aged 28±2 years) on 2 occasions, 3 days apart. In randomized, single blind order, subjects received pretreatment with either placebo or intravenous ANF(99–126) (bolus 100 g/kg, 30-min infusion of 0.1 g/kg-min). Subsequently, on both occasions subjects received a combined intravenous bolus injection of pituitary releasing hormones (200 pg thyrotropin releasing hormone, 100 g gonadotropin releasing hormone, 50 g growth hormone releasing hormone and 100 g human adrenocorticotropin releasing hormone; Bissendorf, Hannover, FRG). Plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), thyrotropin (TSH), prolactin, ANF and cyclic guanosine monophosphate (GMP) were determined by radioimmunoassay. ANF(99–126) treatment induced a significant reduction in basal ACTH plasma concentrations and tended to decrease basal plasma cortisol. The TSH response to combined releasing hormone administration was significantly diminished after ANF(99-126) pretreatment. In women, the releasing hormone induced prolactin increase was reduced after ANF(99–126) pretreatment. With the present study design, ANF(99–126) did not alter the basal or releasing hormone stimulated plasma concentrations of cortisol, LH, FSH and GH. Releasing hormone administration did not affect ANF and cyclic GMP plasma levels. In humans, effects of natriuretic peptides on anterior pituitary hormone secretion may have to be considered with investigational or therapeutic administration of ANF analogues or agents interfering with the ANF metabolism.Abbreviations ANF(99–126) human atrial natriuretic factor - ACTH adrenocorticotropic hormone - LH luteinizing hormone - FSH follicle-stimulating hormone - GH growth hormone - TSH thyrotropin - PRL prolactin - cyclic GMP cyclic guanosine monophosphate - TRH thyrotropin releasing hormone - GnRH gonadotropin releasing hormone - GHRH growth hormone releasing hormone - CRH adrenocorticotropin releasing hormone     

Glucose kinetics during prolonged exercise in euglycaemic and hyperglycaemic subjects

To determine the limits to oxidation of exogenous glucose by skeletal muscle, the effects of euglycaemia (plasma glucose 5 mM, ET) and hyperglycaemia (plasma glucose 10 mM, HT) on fuel substrate kinetics were evaluated in 12 trained subjects cycling at 70% of maximal oxygen uptake (VO_{2, max}) for 2 h. During exercise, subjects ingested water labelled with traces of U-¹⁴C-glucose so that the rates of plasma glucose oxidation (R _ox) could be determined from plasma ¹⁴C-glucose and expired ¹⁴CO₂ radioactivities, and respiratory gas exchange. Simultaneously, 2-³H-glucose was infused at a constant rate to estimate rates of endogenous glucose turnover (R _a), while unlabelled glucose (25% dextrose) was infused to maintain plasma glucose concentration at either 5 or 10 mM. During ET, endogenous liver glucose R _a (total R _a minus the rate of infusion) declined from 22.4±4.9 to 6.5±1.4 mol/min per kg fat-free mass [FFM] (P<0.05) and during HT it was completely suppressed. In contrast, R _ox increased to 152±21 and 61±10 mol/min per kg FFM at the end of HT and ET respectively (P<0.05). HT (i. e., plasma glucose 10 mM) and hyperinsulinaemia (24.5±0.9 U/ml) also increased total carbohydrate oxidation from 203±7 (ET) to 310±3 mol/min per kg FFM (P<0.0001) and suppressed fat oxidation from 51±3 (ET) to 18±2 mol/min per kg FFM (P<0.0001). As the rates of oxidation at more physiological euglycaemic concentrations of glucose were limited to 92±9 mol/ min per kg FFM, and were similar to those reported when carbohydrate is ingested, the results of the current study suggest that the concentrations of glucose and insulin normally present during prolonged, intense exercise may limit the rate of muscle glucose uptake and oxidation.     

Life cycle ofHepatozoon mehlhorni. sp. nov. in the viperEchis carinatus and the mosquitoCulex pipiens

Hepatozoon mehlhori sp. nov. and its developmental stages from the tissues of the Egyptian viperEchis carinatus and the mosquitoCulex pipines are described. The erythrocytic parasites were differentiated into the small form (trophozoite) measuring 14.5±0.6×4±0.12 m and the mature form (gametocyte) measuring 17.2±1.6×5.4±0.5m. Merogony took place in the pulmonary endothelial cells and in the parenchyma cells of the liver and spleen of the infected vipers. Two types of meront were found. The large meronts (macromeronts) were 30.2±1.73×22.6±1.2 m in size and yielded 16–40 (average 28) micromerozoites measuring 17.2±0.7×5±0.15 m. The small, meronts (micromeronts) measured 18.2±0.6×13.5±0.5 m and yielded 2–14 (average, 8) macromerozoites that were 15.1±0.12×6.2±0.8 m in size. After syzygy in the haemocoel of the mosquito, the microgamont produced four uniflagel-late microgametes (6.4±0.3×4.5±0.5 m in size, with a short flagellum measuring 3.2±0.1 m); on the 3rd day post-infection (p.i.)., one of these fertilized the macrogamete, giving rise to the zygote. The oocyst developed from the zygote on the 5th day p.i. and measured 135±2.6×120±1.8 m. About 11–60 (average, 35) sporoblasts were formed by centripetal invaginations from each oocyst on the 8th day p.i. and developed into sporocysts on the 14th day p.i. Inside each sporocyst, 5–12 (average, 8) sporozoites, each measuring 12.6±1.2×4.1±0.3 m, developed on the 16th day p.i. According to the above-mentioned characteristics the parasite was recorded as being a new species and was namedHepatozoon mehlhorni. Experimental transmission was accomplished by i.p. inoculation of the infectious stages (sporozoites) into uninfected vipers and led to the appearance of blood stages at 4–6 weeks p.i.Abbreviations BLC Blood capillary - DMS developing merozoites - DSP developing sporoblasts - E erythrocyte - F flagellum - HC host cell - HN host nucleus - M Meront - MA macrogamont/macrogamete - MG Microgamete - MIG microgamont - MS merozoites - N nucleus - NG micleus of the microgamete - OC oocyst - P erythrocytic parasite - PV Parasitophorous vacuole - SP sporoblast (s) - SPC sporocyst (s) - SPR sporozoite (s) - ZY zygote (young oocyst)     

The activation of protein kinase C prevents PGE2-induced inhibition of AVP-dependent cAMP accumulation in the rat outer medullary collecting tubule

Previous studies have demonstrated that prostaglandin E₂ (PGE₂) inhibits arginine vasopressin-(AVP)dependent adenosine 3,5-cyclic monophosphate (cAMP) accumulation in microdissected rat outer medullary collecting tubules (OMCD), by a mechanism unrelated to the inhibition of cAMP synthesis. The potential role of the activation of protein kinase C (PKC) to explain the negative regulation elicited by PGE₂ was investigated in this study. Single OMCD samples were pre-incubated (10 min, 30°C) in the presence or absence of either activators of PKC, phorbol 12-myristate 13-acetate (PMA), 1-oleoyl-2-acetyl-glycerol (OAG), dioctanoylglycerol (DOG) or an inhibitor of PKC, staurosporine (SSP). These compounds were present also with the agonists tested during the incubation period (4 min, 35°C). In contrast to PGE₂, activators of PKC did not decrease AVP-dependent cAMP accumulation (mean ±SEM): 1nM AVP=47.1±6.8 fmol · mm^–1· 4 min^–1; AVP + 0.3 M PGE₂=20.1±2.7, P<0.01 versus AVP; AVP + 10 nM PMA=42.0±4.7, NS versus AVP; AVP + 50 g/ml OAG=44.1±4.8. NS versus AVP, N= 5 experiments. However, 10 nM PMA prevented PGE₂-induced inhibition: AVP + PGE₂= 44.2±3.5% of the response to AVP and 90.3±3.2% without and with PMA respectively, N= 16. Similar results were obtained with either 50 g/ml OAG or 25 g/ ml DOG (AVP + PGE₂ + OAG=92.9±6.6% of the response to AVP, N= 8; AVP + PGE₂ + DOG=94.1 ±5.3%, N= 7). OAG, DOG, PMA or PMA + PGE₂ had no intrinsic agonist activity in the rat OMCD and the addition of an inactive phorbol ester did not prevent PGE₂-induced inhibition. SSP, 50 nM or 0.1 M, did not affect the inhibition due to PGE₂ but abolished the reversion by PMA of PGE₂-induced inhibition. A similar regulation was observed on forskolin-(FK)dependent cAMP accumulation: 5 M FK + 0.3 M PGE₂= 37.7±6.2% of the response to FK; FK + PGE₂ + 10 nM PMA=89.5±6.7%; FK + PGE₂ + PMA + 0.1 M SSP=43.1±7.9%, N= 4. The inhibition induced by an ₂-adrenergic agonist, clonidine 1 M, was not blocked by the activation of PKC. In fura-2-loaded OMCD samples, 10nM PMA decreased by 63.3±5.0% and by 57.2±7.1% the peak and plateau phases, respectively, of the increase in intracellular calcium concentration ([Ca²⁺]_i) obtained with PGE₂ when compared to control responses in the same tubules (n=12) and did not affect the increase in [Ca²⁺]_i induced by 0.1 mM carbachol. It is concluded that: (1) in the rat OMCD the activation of PKC by PMA or analogues of diacylglycerol did not reproduce PGE₂-induced inhibition of AVP- or FK-dependent cAMP accumulation, but prevented specifically this inhibitory action; and (2) this reversion might be the consequence of the effect of PKC activation which impaired the rises in [Ca²⁺]_i induced by PGE₂.     

Caffeine elimination: A test of liver function

Summary Fasting plasma caffeine concentration and various parameters of caffeine elimination from plasma obtained after a standardized oral dose of 140 mg caffeine have been compared in nine patients with liver cirrhosis, eight patients with non-cirrhotic liver disease and ten healthy volunteers with regard to their ability to discriminate between the different groups. Fasting plasma caffeine concentrations were significantly higher in cirrhotics (11.1±10.5 mol/l) than in healthy volunteers (1.5±0.8 mol/l). The respective values measured in patients with non-cirrhotic liver disease (3.1±3.1 mol/l) did not differ significantly from the controls. Plasma disappearance rate and clearance of caffeine were significantly decreased in cirrhotics (0.11±0.02 h^–1; 1.0±0.3 ml/min per kg) and in patients with non-cirrhotic liver disease (0.18±0.04 h^–1; 2.2±0.7 ml/min per kg) as compared to healthy volunteers (0.23±0.04 h^–1; 3.1±0.9 ml/min per kg). Plasma caffeine concentration determined 12 h after administration of the test dosage discriminated best between patients with cirrhosis (5.4±1.6 mol/l), patients with noncirrhotic liver disease (2.0±1.4 mol/l) and healthy volunteers (0.8±0.2 mol/l). These results, the safety of the test compound and the simplicity of a single caffeine determination in plasma 12 h after a standardized dose of caffeine make this test attractive for evaluation of liver function.     

Current usefulness of procaine penicillin in the treatment of pneumococcal pneumonia

The aim of this study was to determine whether procaine penicillin could be used in the treatment of suspected pneumococcal pneumonia of mild to moderate severity in an area with a high prevalence of penicillin resistance. Forty-nine patients were treated with 1.2·10⁶ U of i.m. procaine penicillin every 12 h. By intent-to-treat analysis, 40 of 49 patients were cured and no patient died.Streptococcus pneumoniae could be demonstrated in 17 patients; 5 of 17 isolates were resistant to penicillin (MICs 0.25–4 g/ml). Fifteen of 17 patients were cured with procaine penicillin, one presented allergy, and one was a therapeutic failure. Mean penicillin serum levels were 2.39±1.16 g/ml (peak) and 0.61±0.38 g/ml (trough). The results suggest that procaine penicillin may still be useful in the empirical therapy of suspected pneumococcal pneumonia.     

Effect of the new somatostatin analogue SMS 201-995 on exogenously used insulin

Somatostatin and somatostatin analogues are inhibitors of insulin,glucagon, and growth hormone secretion. However, it has not been determined whether it is somatostatin or its analogues which affect these hormones when used concomitantly. The effect of the somatostatin analogue SMS 201-995 on exogenously infused insulin was observed in ten healthy volunteers. The study was carried out on two occasions with at least a 1-week interval. Each subject was infused with saline throughout the study and insulin at a rate of 40 mU/kg per hour between 60–160 min of the study (step A) or SMS 201-995 in a 75 g IV bolus following at a rate of 75 g/h for 160 min and insulin at the same rate and duration (step B). Hyper-insulinemia and SMS 201-995 significantly suppressed C-peptide secretion, but the degree of C-peptide suppression was greater in the SMS 201-995 infused step than in the insulin-only infused step. Blood glucose levels decreased markedly throughout the infusion of insulin with or without SMS 201-995. In step B, the decrease in blood glucose was greater than in step A. Insulin levels in step B increased to higher levels than in step A (from 81.1 ± 7.7 to 363.9 ± 22.7 mmol/l and from 82.7 ± 8.6 to 229.0 ± 23.4 mmol/l, respectively). These results show that SMS 201-995 increases the level of exogenously infused insulin. This is probably due to the impaired clearance of exogenous insulin. Correspondence to: M. Bayraktar     

Insulin and C-peptide co-localization in theβ granules of normal human pancreas and insulinomas

Summary It has been shown, by using the immunogold technique, that C-peptide and insulin are co-localized in the mature granules of human pancreatic cells and insulinomas with typical granules. The mean gold bead densities of both C-peptide and insulin were at least twice as high in the normal pancreas when compared with the insulinomas. The mean granule diameter of the insulinoma cells (D=0.30 ±0.12 m) was smaller than that of human pancreatic cells (D=0.45 ±0.15 m). The morphometric data indicate that each of the antigens (C-peptide and insulin) is distributed similarly in the halos and the dense cores of the granules. Thus, no topological segregation of these two antigens occurs within the granules of either normal human pancreas or insulinomas.     

Trypanocidal activity of a myristic acid analog in axenic cultures ofTrypanosoma evansi

The growth of bloodstream forms ofTrypanosoma evansi in axenic culture was inhibited by incubation with 11-oxatetradecanoic acid (O-11), an analog of myristic acid. Parasites isolated from Asia, Africa and South America were affected to a similar extent in measurements using three different assay systems concerned with different aspects of trypanosome growth and metabolism. The concentration of O-11 that inhibited trypanosome growth by 50% (LD₅₀) was 3.7±0.2 M as measured by direct counting of survivors using a haemocytometer, 5.1±2.0 M in a colorimetric test based on the formation of a formazan product, and 8.8±3.7 M by estimation of pyruvate. The activity of the drug was enhanced by the addition of fatty-acid-free bovine serum albumin as a carrier protein to the culture medium at an optimal concentration of 5 mg/ml. Increasing amounts of the donor horse serum used for routine maintenance of these cultures, which is normally the only source of myristic acid for these trypanosomes, also affected the toxicity of the drug, in this case increasing the LD₅₀.     

Transformation of Saccharomyces cerevisiae with plasmids containing fragments of yeast 2 μ DNA and a suppressor tRNA gene

Hybrid plasmids have been constructed containing segments of the yeast plasmid 2 DNA, the yeast ochre-suppressing SUP4.0 gene and the bacterial plasmid pBR322. Yeast transformation is detected with a host containing multiple ochre auxotrophic mutations. The transformed SUP4.0 gene is active and can promote growth in the absence of all the requirements. Plasmids containing different fragments of 2 DNA all appear to be active in high frequency transformation of yeast containing 2 DNA, except those containing the HindlII-D fragment. The transforming plasmids undergo recombination with the indigenous 2 DNA. Integration of the transforming plasmid into the host chromosome has been detected by hybridization of restriction enzyme cleaved DNA with labelled pBR322. The plasmids contain restriction enzyme sites which can be used for cloning other genes into yeast.Abbreviations kb kilobase pair - 2 the yeast plasmid of 6.2 kb size     

Microtubule stability in severed axons

Summary We examined severed axons of cat sympathetic nerves and severed neurites of cultured chick sensory neurons for evidence of extensive microtubule depolymerization. Cat sympathetic fibres fixed at various times after severing were cross-sectioned for electron microscopy from both cut ends. The number density of microtubules was determined at various times after severing for matched proximal and distal regions equidistant from cut ends. These data show that the number density of microtubules was nearly identical in proximal and distal fragments at 10, 20 and 60 min and at distances between 10 and 50 m from the cut ends. In chick sensory neurites the microtubule array was examined in longitudinal sections. In order to define objectively a normal microtubule array, the distance between 100 microtubule pairs was measured in seven control neurites, giving a mean distance (±S.D.) of 33nm±19nm. A normal array of microtubules was defined as having microtubules within 52nm of their nearest lateral neighbour. Among 11 neurites at times from 1 to 15 min after transection, the mean distance from the cut tip to the first microtubule was 1.3 m in proximal fragments and 0.5 m in distal fragments. The mean distance to the normal microtubule array was 2.8 m in proximal fragments and 2.1 m in distal fragments. There was no trend or pattern with respect to the times after severing that the neurite was fixed and the amount of microtubule depolymerization. Our results show no evidence for stabilization of axonal/neurite microtubules by capping structures at their ends. We conclude that microtubule instability is unlikely to play a role in the response of axons to axotomy.     

Etude d'une infection microsporidienne due àNosema birgii n.sp. (Microsporida,Nosematidae) chezMesoplatys cincta Olivier, 1790 (Coleoptera,Chrysomelidae)

Résumé Nosema birgii n.sp. (Microsporida, Nosematidae) a été trouvée dans les larves et adultes deMesoplatys cincta (Coleoptera, Chrysomelidae) du Sénégal. Elle attaque divers tissus et provoque une infection généralisée. Son cycle de développement et l'ultrastructure de ses stades sont typiques du genreNosema. Les spores vivantes sont ovales et allongées et mesurent 6,20±0,21 m×3,5±0,18 m. Leur filament polaire décrit 12 à 14 tours de spire et leur polaroplaste possède une partie antérieure lamellaire et une partie postérieure vésiculeuse.

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Study of a microsporidian infection caused byNosema birgii n.sp. (Microsporida, Nosematidae) inMesoplatys cincta Olivier, 1790 (Coleoptera, Chrysomelidae)

Nosema birgii n.sp. (Microsporida, Nosematidae) was found in larvae and adults ofMesoplatys cincta (Coleoptera, Chrysomelidae) from Senegal. It attacked various tissues and caused a general infection. Its life cycle and the ultrastructure of its stages were typical of the genusNosema. The living spores were oval, elongate and measured 6.20±0.21 m×3.5±0.18 m. Their polar filament formed 12 to 14 coils and their polaroplast was lamellar and vesicular.

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Abreviations CC centre cinétique - CP capuchon polaire - CS cavité sporale - EN endospore - EX exospore - FP filament polaire - M membrane plasmique - MA masse amorphe - N1,N2 noyau - PL polaroplaste lamellaire - PV polaroplaste vésiculeux - RC reliquat du cytoplasme - RE reticulum endoplasmique - VP vacuole postérieure