Histamine stimulation of cyclic AMP accumulation in astrocyte-enriched and neuronal primary cultures from rat brain

Histamine stimulates cyclic AMP accumulation in astrocyte-enriched and neuronal primary cultures from rat brain in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine. The response in the astrocyte cultures (Emax = 304 +/- 44% over basal, EC50 = 43 +/- 5 microM) was much higher than in neuronal cultures (Emax = 24 +/- 2%, EC50 = 14 +/- 7 microM). The histamine effect in astrocytes was competitively inhibited by the H2 antagonists cimetidine (Ki = 1.1 +/- 0.2 microM) and ranitidine (Ki = 46 +/- 10 nM) but was insensitive to the H1 antagonist mepyramine (1 microM). The two selective H2 agonists impromidine and dimaprit behaved as partial agonists and showed relative potencies (139 and 0.5, respectively) consistent with an interaction with H2 receptors. The more selective H1 agonist 2-thiazolylethylamine (0.01-1 mM) did not potentiate the response to impromidine (10 microM). Thus, in contrast to what is generally observed in intact cell preparations from brain, the histamine-induced cyclic AMP accumulation in astroglial cells is mediated solely by H2 receptors. The small effect shown in neuronal cultures also appears to be mediated by H2 receptors.

[The development of a linear function for stratifying the risk of hospital mortality in acute myocardial infarct]

In spite of conventional treatment in a Coronary Unit, there is a group of patients with acute myocardial infarction who present a high mortality index. A more aggressive attitude (coronariography, angioplasty, and/or emergency coronary bypass) could improve the prognosis in some of these patients but can only be performed in a limited number of centers. In the present work, we have reviewed data obtained from the Emergency Room on 167 patients diagnosed of myocardial infarction. The variables that were correlated to mortality were: age, heart rate, blood pressure, presence of rales, radiologic heart failure cardiomegaly, ventricular extrasystoles in ECG and delay in arrival to hospital. We obtain a lineal function (z = 24.6 X1 - 0.4 X2 + 0.2 X3 + 11) which combining ventricular extrasystoles, diastolic arterial pressure, and heart rate permits to differentiate three risk groups: low, medium and high, associated to hospital mortality rates of 5.7, 36.4 and 83.3%. We suggest the use of a function of this type to select those patients who should be sent to a hospital with facilities for emergency coronary surgery.

[The electrocardiographic changes in constrictive pericarditis before and after pericardiectomy. The role of the myocardium in the genesis of preoperative electrocardiographic changes]

We studied 19 patients diagnosed of chronic pericarditis and treated surgically with pericardiectomy, to evaluate the role of the pericardium and myocardium on the preoperative electrocardiogram. Before surgery, there was atrial fibrillation in 17 cases, the P axis was between 0 and +70 and pseudomitral morphology was found in 10 of the 12 cases with normal sinus rhythm. The mean voltage in the QRS complex was (13.8 mm), and the R wave in V5 8.6 mm. The T wave was negative in 17 patients. After surgery there was only a case of atrial fibrillation that converted to normal sinus rhythm; the P wave axis moved to the right between +30 and +150 (p less than 0.002), the pseudomitral morphology of the P changed to normal in 3 cases, the voltage of the QRS increased to 16.7 mm (p less than 0.003) and that of the R wave in V5 to 9.4 mm (p less than 0.001). The T wave became positive in only 3 cases. Because of the persistence of some alterations, we concluded that both components, pericardium and myocardium are important in the changes of the electrocardiogram of constrictive pericarditis.

Histamine stimulates glycogen breakdown and increases 45Ca2+ permeability in rat astrocytes in primary culture

In astrocyte-enriched cultures from rat brain hemispheres prelabeled with [3H]glucose, histamine stimulates [3H]glycogen breakdown in a concentration-dependent manner, with an EC50 of 0.6 microM. This effect can be induced by activation of both H1 and H2 receptors independently. Thus, neither 1 microM promethazine, an H1 antagonist, or 100 microM metiamide, an H2 antagonist, inhibited the glycogenolytic response to histamine unless they were present together. In addition, the maximal effect of histamine (55% decrease in [3H]glycogen) was also elicited by 300 microM 2-thiazolylethylamine, an H1 agonist, and by 1 mM dimaprit, an H2 agonist. These agonist effects were inhibited by promethazine and metiamide, respectively, and were not additive, indicating that the same glycogen pool was affected. Histamine was more potent in eliciting glycogenolysis through H1 (EC50 of 0.4 microM in the presence of 100 microM metiamide) than through H2 (EC50 of 3.3 microM in the presence of 1 microM promethazine) receptors, as also shown previously for the H1-mediated phosphoinositide hydrolysis compared with the H2-mediated cAMP formation in the same cells. Both dibutyryl cyclic AMP and the Ca2+ ionophore A23187 could independently mimic the glycogenolytic effect of histamine, whereas the absence of extracellular Ca2+ abolished the H1 component of the response. Histamine also stimulated rapid transmembrane 45Ca2+ influx (maximum, 48% of basal at 15 sec) and efflux (maximum, 25% of basal at 1 min) in astrocytes by activation of H1 receptors. This histamine-increased 45Ca2+ entry was abolished by the nonspecific Ca2+ channel blocker lanthanum but not by the voltage-operated Ca2+ channel inhibitor nifedipine. The enhanced 45Ca2+ release was more a consequence of the histamine-increased Ca2+ permeability than intracellular Ca2+ mobilization, because it was largely diminished when Ca2+ entry was prevented and was little affected by pretreatment of the cells with 12-O-tetradecanoyl-phorbol-13-acetate. Thus, the histamine-induced glycogen breakdown in astrocytes may involve increases in cAMP formation and in intracellular Ca2+ levels, this latter resulting mainly from H1-mediated extracellular Ca2+ uptake.

[Differences by sex in the presentation and follow-up in the first year of acute myocardial infarct]

Three-hundred and nine patients, 242 males and 67 females diagnosed of myocardial infarction were studied during the acute phase and followed for a year to evaluate any differences. The corrected incidence was greater amongst males, 11.1 vs 3.6/10,000 inhabitants. The presenting age was significantly lower in males below 50 and greater in women above 70. Hypertension, hypercholesterolemia and sedentariness were more prevalent amongst women; smoking was more prevalent amongst males. Infarction presentation was typical in both sexes being significant a 5 hour delay in arriving to the hospital in female patients. On hospital admission Killip III-IV was significantly more frequent amongst women (17% vs 4.6%). Hospital mortality although it was higher in women this was not statistically significant (19.4% vs 14.4%). During follow up there was a better control of risk factors in the male patients. Heart failure and mortality were greater amongst women during the first three months (p less than 0.001). Mortality differences continued being statistically significant during the following three months. From the sixth month to the first year, mortality rates were similar. The study suggests that infarction prognosis is worse in females.

[A combination of ampicillin and sulbactam: effect on aerobic and anaerobic gram-negative bacteria]

The antibacterial activity of the association of ampicillin and sulbactam (2:1) upon strains of aerobic and anaerobic Gram negative agents was assayed. Inhibition of B-lactamases from intact and disrupted cells of some selected strains by sulbactam was also determined. Susceptibility was found in 34% and partial inhibition in 48%; 18% were fully resistant. Synergy between ampicillin and sulbactam was found upon ampicillin susceptible strains. This effect might reflect higher degree of binding of the inhibitor to PBP's in the absence of a trapping effect produced by B-lactamases. Anaerobic microorganisms were found to be highly susceptible to this association of B-lactams. Adequate penetration of the inhibitor into periplasmic space of Gram negative bacilli was deduced by the similar decrease of B-lactamase activity observed in intact and disrupted cells treated with sulbactam.

Acute polyneuropathy in critically ill patients

We studied five patients in the intensive care unit (ICU) with acute polyneuropathy. All had previously presented severe infectious processes, accompanied by diverse organ failure accompanied by the Adult Respiratory Distress Syndrome (ARDS) in all cases. Two patients died and the three survivors suffered severe motor deficiencies. Electromyographic studies revealed axonal damage which predominantly affected motor neurons. Cerebrospinal fluid was normal in all the patients except one, who showed a moderate increase of lymphocytes. The common causes of polyneuropathy were excluded, but in all cases a nutritional disorder was detected, based on laboratory values of proteins, serum albumin and transferrin. We conclude that polyneuropathy is relatively frequent among critically ill patients and must be closely monitored because of diagnostic difficulties and the repercussions on the progress of these patients. In spite of uncertainties about its cause, it appears to be related to severe infectious processes, ARDS, and nutritional disorders.

Kaposi's sarcoma in Colombia

Seventy-nine cases of Kaposi's sarcoma (KS), which correspond to one of every 1,000 malignant tumors, were reviewed at the National Institute of Cancer (NIC), Bogotá, Colombia, from 1935 to 1985. Seventy-four percent of the patients were older than 65 years of age. The male to female ratio was 8:1. In all cases, plaques and nodules first appeared in the lower limbs; they were symmetrical in 47% of the cases and ulcerated in 25%. No generalized or epidemic forms were seen. Esophageal squamous cell carcinoma concurrent with KS was observed in one case. KS developed several years after treatment for follicular lymphoma and chronic lymphocytic leukemia in two patients. An angiosarcomatous variant and one fibrosarcomatous change were seen. Ten cases studied for factor VIII expression through the peroxidase-antiperoxidase (PAP) technique were all reactive. We conclude that in Colombia before 1985, KS behaved as a chronic multicentric Stage I disease without a tendency to associate simultaneously with malignant conditions.

Differential effects of chronic treatment with mianserin and protryptiline on rat brain cortical alpha 1-adrenoceptors

Chronic administration of mianserin induced an increase in the density of [3H] prazosin binding sites (23%) in membranes and in the maximal noradrenaline stimulation of phosphoinositide breakdown (81%) in slices from rat brain cortex. In contrast, a similar treatment with protryptiline did not induce any significant changes. These findings suggest that the effects of antidepressant drugs on rat brain cortical alpha 1-adrenoceptors may depend on the characteristics of the drug used.

Thallium-201 myocardial planar scintigrams. Alignment of stress and rest images by correlation

The utility of the correlation for alignment of myocardial perfusion imaging with 201TI was studied. The tests were made by numerical simulation of a heart model with an artefact and a theoretical background superimposed in normal and pathological situations. The methods used were bidimensional and unidimensional correlation techniques and were applied either with or without previous background subtraction. Our results show the suitability of this alignment technique, useful in finding the displacement between images with an average error inferior to one pixel in different situations of myocardial damage.

Methods of background subtraction in myocardial perfusion imaging with thallium-201: a comparative study in the presence of an artefact

For thallium imaging quantitation, a simulation study has been made using different methods of interpolation for background subtraction and studying their behaviour in the presence of an artefact. Two artefacts were used, one simulating hepatic or splenic uptake and the other diaphragmatic activity. The interpolative methods used were three classic techniques using standard masks. Their algorithms were modified so that they could also be used with arbitrarily shaped masks enclosing myocardium, and a comparison between the original and modified methods was made. Our results show an improvement when using the modified algorithms adapted to the arbitrarily outlined mask.

[Effect of nitrendipine in the treatment of mild or moderate essential arterial hypertension]

We studied 30 ambulatory patients with mild to moderate essential arterial hypertension, treated with the new calcium antagonist nitrendipine, during a follow-up period of six months and after a three week placebo period was completed. Nitrendipine initial dosage was 20 mg, given once daily in the morning. Normalization of blood pressure was achieved in every patient after three months of treatment, with a p less than 0.0001 since the first month and throughout the whole period. No concomitant changes in heart rate or vascular risk factors were observed. Eight patients needed their individual dosages to be doubled (40 mg) to achieve a complete normalization of their blood pressure values; four of them took the whole dosage once daily. We had to stop treatment in three patients because of significant worsening of previous symptoms. Although there was a 16.6% total incidence of secondary effects, the compliance was over 90%, which tells us about the relatively small importance of secondary effects observed. Flushing, which was present in five patients, was the most common secondary effect. Nitrendipine is an excellent antihypertensive drug, easy to use and responsible for a low number of disabling secondary effects, usually appearing in previously very symptomatic patients.

Presence of melatonin in the umbilical cord blood of full-term human newborns

The present study was designed to determine whether melatonin circulates in the umbilical cord blood of healthy human newborns and whether the concentrations of this hormone follow a circadian rhythm at birth. Umbilical cord blood was collected from full-term human newborns at the time of delivery. Serum melatonin was extracted with diethylether and determined by radioimmunoassay by using radioiodinated melatonin and rabbit antimelatonin antiserum. Significant amounts of melatonin were detected in the sera obtained from umbilical cord blood. When serum melatonin concentrations of human newborns were represented over 6-h periods or hour by hour over the 24 h of 1 d, similar hormone concentrations were found consistently. These results indicate that melatonin is present in quite high levels in the umbilical cord blood, which may be, at least in part, of maternal origin. Also, our results suggest the absence of a melatonin circadian rhythm in human newborns, which may reflect an immaturity of the components involved in melatonin synthesis.

[Larval density of Anopheles (N) albimanus Wiedemann, 1821 in relation to phenology of Oryza sativa (Linnaeus) rice]

The larval density of Anopheles (N) albimanus Wiedemann, 1821, is linked with rice phenology in the two crops of the year (summer and winter). It was determined that a higher density agrees with the second stage of the vegetative cycle of the culture named beginning of shooting processes and the formation of the panicular primordium. The number of anopheline larvae was higher in the summer.

Histamine H1-receptors mediate phosphoinositide hydrolysis in astrocyte-enriched primary cultures

Astrocyte-enriched primary cultures of newborn rat brain hemispheres, prelabeled with [3H]inositol, accumulated [3H]inositol phosphate but not [3H]inositol bis- and tris-phosphate, after exposure to histamine for 60 min in the presence of 10 mM LiCl. The response to histamine was not a function of contaminating meningeal fibroblasts since no accumulation of [3H]inositol phosphate was elicited by histamine in meningeal cultures. The stimulation of phosphoinositide hydrolysis by histamine in astrocytes was dose-dependent (EC50 = 1.7 microM, maximal effect = 345% over basal levels) and was mimicked by several H1-receptor agonists. The use of selective receptor antagonists confirmed that the histamine response was the result of activation of H1-receptors. The histamine-induced [3H]inositol phosphate accumulation was completely abolished by omission of Ca2+ from the incubation medium. Astrocyte membranes specifically bound the radiolabeled H1-antagonist, [3H]mepyramine with an affinity (Kd = 5.9 nM) and a density of binding sites (Bmax = 113 fmol/mg protein) similar to rat brain. These results demonstrate the presence of functional histamine H1-receptors in rat brain astrocytes and suggest a role for histamine as a neuromodulator of astrocyte function.

Abnormal scintigraphic evolution in AA hepatic amyloidosis

A patient with AA amyloidosis secondary to ankylosing spondylitis showed intense liver uptake of Tc-99m MDP on bone imaging. The biopsy showed hepatic amyloid deposition. A repeat bone scan with Tc-99m MDP 1 year later was negative, although the clinical signs and liver function tests of the patient had not changed. A mechanism might exist, other than the affinity of amyloid to calcium, which would explain the extraosseous uptake of pyrophosphates and diphosphonates in organs and soft tissues affected by systemic amyloidosis.

Renal leiomyosarcoma in a patient with tuberous sclerosis

We report the case of a 16-year-old patient with tuberous sclerosis that presented as renal leiomyosarcoma. This is an exceptional form of presentation of this tumor. An angiomyolipoma has to be first suspected in this group of patients. If the diagnosis is not confirmed by the imaging studies, radical surgery is recommended.

Structure of kerlinic acid from Salviakeerlii. Chemical correlation with melisodoric acid

The structure of kerlinic acid, a neo-clerodane diterpenoid isolated from Salviakeerlii (Labiatae), was deduced from spectral data and chemical correlation with melisodoric acid.

[Mucolipidosis II or "I-cell disease" in the newborn infant. 2 new cases]

Clinical and biochemical findings of two patients with neonatal mucolipidosis II are presented. Characteristic coarse facial features, shortness of stature, psychomotor retardation and vacuolated lymphocytes were observed in both cases. However, in one case symptoms presentation was earlier and course of the disease was markedly more severe, with death occurring at the age of 3 months. Biochemically similar increase of serum multiple lysosomal enzymes and decrease of fibroblast activities was demonstrated in both patients. Authors have found elevations of some acid hydrolases in sera from parents (obligate heterozygotes) of both patients and in individuals from two more families also obligated carries.

Histamine-stimulated phosphoinositide hydrolysis in developing rat brain

Histamine stimulation of phosphoinositide breakdown has been studied in brain cortex from developing rats by measuring the accumulation of [3H]inositol monophosphate in lithium-treated slices prelabeled with [3H]inositol. Histamine stimulated phosphoinositide hydrolysis as early as day 3 after birth. The maximal response increased about 3-fold up to day 15 and remained essentially at the same level until adulthood. This developmental pattern contrasted with the 8-fold increase in [3H]mepyramine binding to histamine H1 receptors which takes place from the first to the end of the fourth week of life. Nonlinear regression analysis of concentration-effect curves for histamine generated at 6, 10, and 15 days of age revealed the presence of two components in the response, whereas a single component was found in adults. A high potency component showed EC50 values increasing from 6.4 microM at day 6 to 26.5 microM at day 15, and its contribution to the maximal response augmented from 65.8% to 78.9% during the same period. In 6-day-old animals, the H1 receptor agonists N alpha-methylhistamine and N alpha,N alpha-dimethylhistamine produced single-component responses with maximal effects similar to that estimated for the high potency component for histamine, and their relative potencies were consistent with an H1 receptor-mediated response. Inhibition constants for mepyramine, calculated from the parallel displacement of the concentration-response curves for N alpha-methylhistamine and the high potency component for histamine (6.3 nM and 10.8 nM, respectively) closely agreed with the reported affinity of rat brain H1 receptors for this compound. The low potency component of the response (EC50 = 175 microM at day 6 and EC50 = 260 microM at day 15) did not involve histamine-H2, serotonin 5-HT2, alpha 1-adrenergic, or muscarinic receptors. Pretreatment of 6-day-old cortical slices with the irreversible antagonist phenoxybenzamine, at concentrations that completely abolish [3H]mepyramine binding, left about 25% of the response to 1 mM histamine unaffected. This portion of the response, which was, moreover, insensitive to 1 microM mepyramine, was of a magnitude similar to that of the low potency component. Thus, at early stages of rat brain development, histamine induces phosphoinositide hydrolysis in part through a mechanism different from activation of H1 receptors. The loss of histamine potency and efficacy at H1 receptors throughout development is discussed and the natural occurrence of H1 receptor subsensitivity suggested.

Estimation of the daily intake of nitrates and nitrites which may be consumed by students 12-17 years old in secondary schools in the city of Havana

In the present article we offer informations regarding the estimated amounts of nitrates and nitrites which may be consumed by 12,000 students 12 to 17 years old, who attend boarding schools. The method of analysis used to determine nitrates and nitrites is that reported by the Joint FAO/WHO Expert Committee using a cadmium reducing column. The estimated quantities of nitrates and nitrites which these students may consume according to their food intake are smaller than those recommended as admissible daily intake by the Joint FAO/WHO Expert Committee on Food Additives.

Measurement of nasal mucociliary transport rate in normal man

After reviewing the main methods existing to calculate the rate of the mucociliary transport, the authors describe their personal technique. A 99mTechnetium Sulphur Colloid drop is deposited in the nasal fossa, which is carried away by the cilia down to the rhinopharynx and followed by a gamma camera. To calculate the transport rate, a new method of quantification has been introduced, based on the formation of a parametric image. A study was carried out in 14 males without any pathology of the upper airways, obtaining a mean velocity of 5.3 mm per min (range 3.3.-8.2).

Phosphoinositide hydrolysis mediated by histamine H1-receptors in rat brain cortex

Histamine stimulated the accumulation of [3H]inositol 1-phosphate in the presence of lithium in [3H]inositol-prelabelled slices from rat brain cortex in a concentration-dependent manner, with an EC50 value of 94.7 microM. High concentrations of antagonists of histamine H2 receptors, muscarinic receptors, alpha 1-adrenoceptors and serotonin receptors did not inhibit the effect. The histamine H1-receptor antagonists mepyramine, triprolidine, promethazine, d-chlorpheniramine and the tricyclic antidepressant doxepin inhibited the response with Ki values corresponding to an interaction with histamine H1-receptors. The EC50 for the response was about three times lower than the Ki value (approximately 300 microM) for the inhibition by histamine of [3H]mepyramine binding to membranes from rat brain cortex. Partial inactivation of H1-receptors with the alkylating antagonist phenoxybenzamine resulted in similar reductions in [3H]mepyramine binding sites and in the maximal histamine-induced [3H]inositol 1-phosphate accumulation, without affecting the KD for the radioligand or the EC50 for the response. The apparent dissociation constant for histamine calculated from these experiments (KA = 92.2 microM) was not different from the EC50 value. The present results indicate that histamine-stimulated phosphoinositide hydrolysis in rat brain cortex is mediated by H1-receptors and that no receptor reserve is present.

Nasal mucociliary transport in laryngectomees

A study has been carried out to assess the mucociliary function of nasal mucosa in 30 patients: 16 had undergone surgery due to larynx malignancy and the remaining 14 were divided in two groups. The first group was composed of seven patients suffering from larynx cancer but not operated, and the second group of seven had pathology not related to the airways (control group). The method used a 99mtechnetium sulphur colloid drop deposited on the nasal mucosa of one nostril. To calculate the rate of transport, a new method of quantification has been introduced, based on the formation of a parametric image. The mean velocity in laryngectomees was 3.6 mm/min (range 1.1-6.4). It was compared with the group of 14 patients without tracheostomy (mean 5.3, range 3.3-8.2). An impaired Student's-t-test gave a significant difference between both groups (P less than 0.005). The comparison between patients with nonoperated larynx cancer and normals gave a nonsignificant difference. The 16 operated patients were arbitrarily divided into two groups as per the time elapsed from laryngectomy; seven were studied within the first 3 years of operation and seven other patients after this term. The comparison between them was not significant.

[3H]mepyramine binding to histamine H1 receptors in bovine retina

The promethazine-sensitive [3H]mepyramine binding was used to determine the presence of histamine H1 receptors in membranes from bovine retina. Specific mepyramine binding to retinal membranes was reversible, saturable and of high affinity. The apparent dissociation constant (KD = 2.2 +/- 0.4 nM) and the density of binding sites (Bmax = 60.9 +/- 5.1 fmol/mg protein), obtained in equilibrium studies, were similar to those found in bovine brain cortex. Binding was stereospecific and the inhibitory potencies of H1 and H2 antagonists indicated that [3H] mepyramine binding sites in the retina have characteristics of H1 receptors.

Effect of thyroid state on histamine H1 receptors in adult and developing rat brain

The effect of thyroid status on histamine H1 receptors in adult and developing rat brain was investigated using the (3H) mepyramine binding assay. Hypothyroidism induced by treatment with 6-n-propyl-2-thiouracil resulted in a 31% decrease in the density and total content of adult rat brain (3H) mepyramine binding sites and a significant retardation of the developmental increase in H1 receptor binding in neonates. At 30 days of age, when euthyroid rats reached binding levels of the adult, hypothyroid animals presented reductions of 22 and 39% in (3H) mepyramine bound per unit weight and per brain respectively. In contrast, hyperthyroidism induced by treatment with L-thyroxine did not alter H1 receptor numbers in the adult rat brain but accelerated the developmental increase in (3H) mepyramine bound per unit weight that reached normal adult levels by 21 days of age. The results suggest that thyroid dysfunction during early life and adulthood may cause derangements of the histaminergic system in the brain.

Hemodynamic effects of vasodilators on pulmonary hypertension in decompensated chronic obstructive pulmonary disease

Vasodilators have been reported to improve the hemodynamic status of some patients with pulmonary hypertension secondary to chronic obstructive pulmonary disease (COPD). We investigated the effects of sodium nitroprusside (50 micrograms/min) and hydralazine (25 mg) on pulmonary hemodynamics in 12 patients during acute exacerbation of COPD. Apart from its known systemic effects, nitroprusside decreased significantly mean pulmonary artery pressure (MPAP) from 36 +/- 10 to 31 +/- 12 mm Hg (p less than .04), decreased slightly pulmonary vascular resistance, and did not change cardiac index. Except for a slight but significant increase in MPAP from 35 +/- 5 to 38 +/- 5 mm Hg (p less than .002), hydralazine produced no significant hemodynamic changes. These results suggest that vasodilator therapy with sodium nitroprusside and hydralazine for pulmonary hypertension secondary to acute COPD is probably not helpful.

Differential effect of pertussis toxin on the affinity state for agonists of renal alpha 1- and alpha 2- adrenoceptors

The effect of pertussis toxin treatment on the guanine nucleotide-induced modulation of the affinity of renal alpha 1- and alpha 2-adrenergic receptors was investigated. Pretreatment of rats with pertussis toxin did not induce any change in the number of or affinity for antagonists of alpha 1- or alpha 2-receptors studied using [3H]prazosin and [3H]yohimbine, respectively. Guanyl-5'-yl imidodiphosphate induced an "up-shift" in the number of alpha 2-adrenergic receptors; this up-shift was not observed for alpha 1-adrenergic receptors. Pertussis toxin treatment decreased the affinity of epinephrine for the [3H]yohimbine-binding sites and reduced the ability of guanine nucleotides to modulate alpha 2-adrenoceptor agonist affinity. The regulation by guanine nucleotides of alpha 1-adrenoceptor affinity for agonists was not altered. These results suggest that the modulation of alpha 1- and alpha 2-adrenoceptors by guanine nucleotides is probably exerted through different molecular entities.

[Fever of unknown origin having a neoplastic etiology]

Fifty three patients having fever of unknown origin according to the criterion of Petersdorf and Beeson were studied. Malignant tumors were found to be the cause in 21 per 100 of the cases. The authors indicate the time required to make an etiologic diagnosis, and the procedures employed for it.