High resolution ultrastructural mapping of total calcium: electron spectroscopic imaging/electron energy loss spectroscopy analysis of a physically/chemically processed nerve-muscle preparation

We report on a procedure for tissue preparation that combines thoroughly controlled physical and chemical treatments: quick-freezing and freeze-drying followed by fixation with OsO4 vapors and embedding by direct resin infiltration. Specimens of frog cutaneous pectoris muscle thus prepared were analyzed for total calcium using electron spectroscopic imaging/electron energy loss spectroscopy (ESI/EELS) approach. The preservation of the ultrastructure was excellent, with positive K/Na ratios revealed in the fibers by x-ray microanalysis. Clear, high-resolution EELS/ESI calcium signals were recorded from the lumen of terminal cisternae of the sarcoplasmic reticulum but not from longitudinal cisternae, as expected from previous studies carried out with different techniques. In many mitochondria, calcium was below detection whereas in others it was appreciable although at variable level. Within the motor nerve terminals, synaptic vesicles as well as some cisternae of the smooth endoplasmic reticulum yielded positive signals at variance with mitochondria, that were most often below detection. Taken as a whole, the present study reveals the potential of our experimental approach to map with high spatial resolution the total calcium within individual intracellular organelles identified by their established ultrastructure, but only where the element is present at high levels.

Expression of muscle calsequestrin in epithelial HeLa cells: distribution and functional role

Calsequestrin is a Ca2+ binding protein expressed by a few cell types (mostly muscle fibers). In these cells the distribution of the protein is within the endoplasmic/sarcoplasmic reticulum, however, not uniformly throughout but at discrete sites of the lumen. In order to investigate the mechanisms of this unusual intracellular distribution together with the possible functions of the protein, we have studied stable transfected clones of epithelial HeLa cells. Treatment of these cells with butyric acid induced a rapid (24 h) and massive (approx. 10-fold) increase of the transfected protein, whereas the other lumenal and membrane proteins of the endoplasmic reticulum were either modified slightly or unchanged. When butyric acid treatment was interrupted the calsequestrin levels returned rapidly (within 24 h) to the pre-treatment level. Such a rapid turnover was due in part to secretion, sustained by both spontaneous and Ca(2+)-dependent release of calsequestrin to the extracellular medium. From the physiological point of view, the transfected cells exhibited only moderate increases of the Ca2+ release responses triggered by either ATP (a ligand addressed to the P2u receptor and working through IP3 generation) or thapsigargin (a blocker of the endoplasmic reticulum Ca2+ ATPase), with no further increase after butyric acid induction of calsequestrin. This result appears to correlate with the occurrence of only small amounts of calsequestrin within the endoplasmic reticulum lumen of all transfected cells. The bulk of calsequestrin, in contrast, was found sequestered within large vacuoles distributed both near the cell surface and, after butyric acid treatment, also in the deep cytoplasm. These vacuoles (possibly a lysosomal subcompartment) appear to contain no Ca2+ as no difference in 45Ca release from transfected cells was observed without or with butyric acid pretreatment when exposed to ionomycin, alone or combined with monensin. We conclude that HeLa cells possess no adequate mechanisms to keep calsequestrin in its physiologically relevant location, the endoplasmic reticulum. In the transfected cell the protein seems therefore to be diverted (possibly by default) to vacuoles destined to be rapidly eliminated by the cell.

Modifications in a flexible surface loop modulate the isozyme-specific properties of mammalian alkaline phosphatases

We have analyzed to what extent the surface loop domain of alkaline phosphatases (APs) is responsible for isozyme-specific functional properties. Unique AatII and RsrII restriction sites were introduced by site-directed mutagenesis at identical positions in murine tissue-nonspecific AP (TNAP) and human placental AP (PLAP) cDNAs to allow the homologous exchange of the loop domain of the TNAP (T domain) and PLAP (P domain) isozymes and the generation of the reciprocally chimeric molecules PLAP-T and TNAP-P. The introduction of the T loop into PLAP reduced the heat stability of PLAP-T to almost that of TNAP. The domain substitution was accompanied by a conformational change that resulted in the loss of immune reactivity with four of 17 epitope-mapped anti-PLAP monoclonal antibodies. The T and P loops provided stabilization to the side chain of specific uncompetitive AP inhibitors. The introduction of the T domain also conferred collagen-binding properties to PLAP-T accounting for half of the binding affinity of TNAP for collagen, while not affecting PLAP binding to IgG. Our data indicate that the surface loop determines overall enzyme stability, differs conformationally in the various isozymes, and modulates catalytic parameters in the presence of protein ligands, thus, accounting in part for isozyme-specific protein interactions.

Pregnancy-associated plasma protein B (PAPP-B): isolation from human late pregnancy serum and biochemical characterization

The pregnancy associated plasma protein B (PAPP-B) was first described by Lin et al. as a glycoprotein with a molecular weight of about 1,000 kD and a serum half life of less than 24 hours after delivery. We isolated PAPP-B from late pregnancy serum using liquid chromatography including HPLC. PAPP-B was found to be a glycoprotein with a molecular weight of 1,300 kD and to be an octadecamer of identical subunits (74 kD each). Cleavage of the carbohydrates with trifluoromethanesulfonic acid reduced the molecular mass to 65 kD (by SDS PAGE, 12.2%). Isoelectrofocusing and titration curves fixed the isoelectric point at 5.3. Spectroscopy measurements between 230 and 360 nm yielded a trp/tyr ratio of 1.1. Amino acid analysis showed that each subunit contained five methionines; this was confirmed by a CNBr cleavage experiment.

Synapsin I partially dissociates from synaptic vesicles during exocytosis induced by electrical stimulation

The distribution of the synaptic vesicle-associated phosphoprotein synapsin I after electrical stimulation of the frog neuromuscular junction was investigated by immunogold labeling and compared with the distribution of the integral synaptic vesicle protein synaptophysin. In resting terminals both proteins were localized exclusively on synaptic vesicles. In stimulated terminals they appeared also in the axolemma and its infoldings, which however exhibited a lower synapsin I/synaptophysin ratio with respect to synaptic vesicles at rest. The value of this ratio was intermediate in synaptic vesicles of stimulated terminals, and an increased synapsin I labeling of the cytomatrix was observed. These results indicate that synapsin I undergoes partial dissociation from and reassociation with synaptic vesicles, following physiological stimulation, and are consistent with the proposed modulatory role of the protein in neurotransmitter release.

[The emergency treatment of supraventricular tachyarrhythmias: the efficacy and safety of intravenous propafenone]

One hundred patients, admitted to the Emergency Unit for paroxysmal supraventricular tachycardia (SVT) with 1:1 AV conduction, atrial fibrillation (af) and flutter (AF) of recent onset (less than 72 hours) were treated with intravenous propafenone (P). The drug was administered at the dose of 70 mg over 5 min, repeated after 10 min if sinus rhythm (SR) was not restored and eventually followed by continuous infusion (0.35-0.50 mg/min) until conversion to SR or during the next 48 hours. Exclusion criteria were ventricular rate < 100/min, R-R intervals > 1 s, clinical signs of heart failure or asthma. Termination of SVT within 30 min was obtained in 94% of the patients, while reversion to SR occurred in 79% with af and in 55% with AF. For af and AF conversion was achieved within 30 min in 49% of overall responders (R), between 30 min and 6 hours in 27% and between 6 hours and 48 hours in 24%. The efficacy of P was significantly influenced by the duration of arrhythmia and left atrial size, measured by 2D-echocardiography. On the contrary, no difference was observed between R and non-R in mean age and in the percentage of primary or relapsing arrhythmias. Adverse effects were encountered in 7 patients: in 1 case worsened arrhythmia and in 6 patients, with long-lasting arrhythmias, congestive heart failure. Neither conduction disturbance nor extra-cardiac complications occurred. In conclusion, P provides effective and safe treatment for paroxysmal atrial tachyarrhythmias, so that it can be considered among the drugs of first choice even in non-intensive care units.

Reflex cardiovascular control in congestive heart failure

This article reviews evidence that the reflex control of the cardiovascular system provided by negative feedback mechanisms is impaired in congestive heart failure (CHF). The impairment involves vagal and sympathetic modulation of the heart exerted by arterial baroreceptors. It also affects baroreceptor control of blood pressure and peripheral vascular resistance, as well as the cardiopulmonary receptor's ability to modulate sympathetic activity. The degree of such impairment is most marked in severe CHF but is also apparent, to a minor degree, in mild heart failure. Reflex impairment is due to a reduction in the receptor signal, but other factor under investigation are probably also involved. Digoxin and other pharmacologic treatments of CHF improve reflex function, thereby facilitating a reduction in the elevated sympathetic activity and a stepping up of the reduced vagal activity typical of CHF. This may be relevant to a patient's prognosis.

Functional evaluation 10 days and 3 weeks after acute myocardial infarction: comparative significance and prognostic value

Early functional evaluation after non-complicated acute myocardial infarction (AMI) is widely recommended because of its prognostic value in the short term. In fact it seems to have a prognostic value within 15-20 days of the AMI, but in this period the patient is particularly controlled and is often still hospitalized. To evaluate the real significance of an early functional evaluation within 10 days of the AMI (mean 8.6 days +/- 1.2) as compared to an identical functional evaluation performed at 3 weeks after AMI (mean 20.16 days +/- 5.38) 25 patients with uncomplicated myocardial infarction were studied. Significant statistical differences were found between the first (ET1) and second (ET2) functional evaluations: they concern the maximal heart rate reached (P less than 0.001), the maximal pressure-rate product (P less than 0.05), the percentage increment of heart rate (P less than 0.01) and the total work performed (P less than 0.001). Agreement between ET1 and ET2 was found in 19 cases; 12 patients showed markers of ischaemia both at ET1 and ET2, while seven were free from ischaemia at both times. In six cases a disagreement between ET1 and ET2 was found: in particular, three cases had ischaemic ET1 and nonischaemic ET2; the reverse was seen in the other three. During follow-up (mean 215.4 days +/- 85.5), the total number of new events (reinfarctions, angina or surgery) among the 25 patients was eight; none occurred within the first 30 days after the AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin by alternative routes of administration

In a study investigating the bioavailability of heparin administered by different routes, we also compared its bioavailability in the dog after oral administration of two enteric-coated formulations, one containing a heparin preparation (ITF-300) and the other sodium heparin. After administration of the formulation containing sodium heparin, there was no heparin in plasma, but when the formulation containing ITF-300 was given, plasma heparin levels were detectable.

[Acoustic, mechanical and electric alternans in heart tamponade. Clinical case and review of the literature]

The uncommon observation of alternation of the first heart sound in intensity, associated with mechanical and electric alternans is reported in a patient with cardiac tamponade due to large hemorrhagic pericardial effusion. Following pericardiocentesis and removal of 400 millilitres of fluid, all alternation phenomena disappeared. The combination of three alternation phenomena may be a helpful physical diagnostic sign of cardiac tamponade. The possible mechanisms of the "alternans" are discussed. It is suggested that variations in ventricular filling and emptying are the relevant pathogenetic factors.

[The Italian Group for the Study of Streptokinase in Myocardial Infarct: Evaluation of the enzymatic curve of creatine kinase]

Within the multicentre trial of the Italian Group for the Study of Streptokinase in Infarct (G.I.S.S.I.), a particular study was planned for the analysis of plasma creatine kinase curves (CK). Serial measurements of total plasma CK from 11,806 pts (5.905 treated with Streptokinase (SK) and 5,901 control pts (C)) were evaluated by the compartment method (Fig. 7), which is commonly used in pharmacological studies. By this method, the plasma enzyme curve is interpreted on the basis of the following kinetic parameters: the fractional rate of input (Ki) and of disappearance (Kd) of enzyme into and from the blood; the plasma cumulative CK activity (Dp); the time interval between the onset of symptoms and the beginning of the ascending CK curve (To); the time from To to the peak CK (Tp). The Dp/Ki ratio was employed for the estimate of myocardial infarct size. From the available data, acceptable CK curves could be derived in 7,632 cases (3,568 treated with SK, 4,064 control pts.). Compared with control group (Fig. 1--Tab. I) the SK treated pts presented increased Ki and Kd values and reduced To, (p greater than 0.001), Dp/Ki (p greater than 0.05). The earlier SK treatment was started, the higher difference (Fig. 2) was observed between the two groups (SK and C). No significant difference was found between the two groups (SK and C) with regard to sex (Fig. 3), age, history of previous myocardial infarct, re-infarction, early post-infarction angina. Statistically significant similar differences of the above parameters between SK and C groups, were also found when various infarct locations were considered, with the only exception of not-Q infarct (Fig. 4). In the cases complicated by pericarditis (Tab. II, Fig. 5), independently of treatment, reduced reperfusion related indexes and increased Dp/Ki ratio were observed. Severe left ventricular impairment (Killip class 4) tends to reduce (Tab. III) the differences in enzyme parameters between the two groups (SK and C). The patients who died (18 hours after the onset of symptoms) exhibited as the only significant difference compared to survivors the infarct-size related CK parameters (Dp/Ki), independently from the treatment. The mathematical model used in this study proved to be easily feasible and useful for the evaluation of the effect of the treatment in acute myocardial infarct.(ABSTRACT TRUNCATED AT 400 WORDS)

[The use of syntropium bromide as an antispasmodic]

The following trials were carried out to evaluate the antispasmodic effect of sintropium bromide in a group of 30 patients. The antispasmodic effect on the gastroduodenal system was observed endoscopically. The results were compared by means of double blind tests carried out using placebo and rociverine. The effect in a group of 10 patients was examined by X-ray of the digestive tract. The effect on another group of 20 patients suffering from abdominal colic was clinically evaluated. Sintropium bromide has a prompt anticholinergic action and for this reason may be used in the treatment of painful conditions of the bile, gastro-enteric and renal tracts, and also during the course of endoscopic examinations.

[An unusual cause of arterial and venous pulmonary hypertension]

A 49 year old woman with syphilis of recent onset was repeatedly admitted to the hospital on account of recurrent dyspnoea and hemoptysis. The symptoms and radiological signs indicated the presence of a "cardiac lung". The ECG disclosed right ventricular overload which was confirmed by echocardiography. The left heart was normal, not only on echocardiography but also on cardiac catheterization, which documented severe pulmonary hypertension, partly precapillary, partly postcapillary. The presence of chronic lung congestion in the absence of pathological findings pertaining to the left heart lead to the diagnosis of pulmonary venous occlusive disease. However, pulmonary angiography showed notable and widespread arterial amputations which are not present in this syndrome. Autopsy provided the correct diagnosis: sclerosing mediastinitis localized at the hilum with prevalent involvement of both arterial and venous pulmonary vessels.

[In-hospital and long-term prognosis in acute myocardial infarction. Comparative longitudinal study of 2 patient groups]

The in-hospital mortality, the causes of death, the actuarial survival curves were compared in two subsequent groups of patients admitted to our CCU for acute myocardial infarction: the first (group A) includes 791 pts, admitted from september '67 to december '72, the second (group B) includes 542 pts admitted from january '78 to june '80. The in-hospital mortality was significantly reduced in group B (A: 186/791, 23.5%; B: 72/542, 13,3%, p less than 0.01). This could be due to a reduction of the number of deaths for cardiogenic shock (A: 71/791, 9%; B: 30/542, 5.6%; p less than 0.01) and to reduction in the mortality rate for pulmonary oedema (from 6% to 1.5%, p less than 0.01), although the frequency of pulmonary oedema was the same during the two periods (A: 205 pts, 26%; B/156 pts 29%). We did not observe any significant difference in the long-term prognosis (54 months: A 79.3%, B 71.5%). The actuarial survival curves overlapped after the 1st semester after discharge. The most frequent cause of death during follow-up was a new myocardial infarction. None in the group A and only 3% in the group B were referred to the surgeon for coronary artery bypass grafting. We conclude that, in spite of a significant reduction of the in-hospital mortality, possibly related to the evolution in diagnosis and management of the disease, the long-term survival was not improved in a non-surgically treated population with myocardial infarction.

[Comparative evaluation of mexiletine and propafenone by dynamic electrocardiography]

We have compared the efficacy of Propafenon and Mexiletine in 12 subjects (7 males and 5 females, age range of 22-61 year) affected by chronic ventricular extrasystolic beats. Propafenon and Mexiletine were orally administered in doses of 900 mg/day and 600 mg/day respectively in a single blind, cross-over fashion. Our results show that: Propafenon is better tolerated; Propafenon has caused a statistically significant reduction of the total number of ventricular ectopic beats/24 hours; the efficacy of Propafenon has been greater than that of Mexiletine (66% and 25% respectively); with both drugs, in 2 cases, there was an increase of the total number of ventricular ectopic beats/24 hours; Propafenon has induced clear-cut electrocardiogram changes (statistically significant lengthening of P-Q and Q-T intervals).

[Benign stenosis of Vater's ampulla]

The classification of benign stenosis of Vater's ampulla is explained and reference is made to 5 years' experience in this field. The preoperative diagnosis of this condition is discussed and an account is given of the results obtained and the postoperative course. Attention is drawn to the very low incidence of postoperative pancreatitis with respect to the surgical methods employed. This incidence is evaluated in the conclusions reached.