Comparison of permanent cardiac pacing and cardiac pacing on demand in mixed carotid sinus syndrome. Acute- and medium-term follow-up study

The aim of the study was to evaluate the importance of atrial synchronism for pacing therapy of patients with mixed carotid sinus syndrome. On 23 patients (21 m, 2 f; mean age 69 +/- 8 years) affected by symptomatic mixed carotid sinus syndrome we performed: 1) the study of ventriculo-atrial conduction, 2) the evaluation of pacemaker effect and 3) the carotid sinus massage in standing position during VVI and DVI temporary pacing. All patients received a permanent DVI pacemaker and then underwent a two-month period single-blind, randomized, cross-over study on DVI vs VVI mode. During DVI period, no syncope occurred in any patients, minor symptoms persisted in 11 (48%) of them; during VVI period syncopes recurred in 3 patients, symptoms requiring the withdrawal of VVI pacing and premature DVI reprogramming in 8, minor symptoms were observed in 17 (74%). A comparison between 14 patients who preferred DVI period (Group A) and the remaining 9 patients who had no preference for DVI and VVI period (Group B) revealed that Group A patients had a greater pacemaker effect (-34 +/- 16 mmHg vs -16 +/- 14 mmHg; p less than 0.02) and a higher prevalence of ventriculo-atrial conduction (78% vs 44%; p = 0.1), while the entity of the systolic pressure fall caused by carotid sinus massage was similar in the two groups both during VVI mode (Group A -51 +/- 16 mmHg vs Group B -56 +/- 27 mmHg) and DVI mode (Group A -38 +/- 17 mmHg vs Group B -45 +/- 17 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis and thermodynamic studies of two new polymers carrying amido and amino groups in the side chains

Two linear vinyl polymers carrying amido and primary amino groups in the side chains were synthesized and characterized. Their behaviour in aqueous solution was investigated by potentiometric, viscometric and calorimetric techniques. In both cases, the basicity constants show a linear dependence on the degree of protonation α, while the enthalpy values of protonation do not. The thermodynamic results demonstrate the important role of hydrophobic interactions on the protonation process.     

Neurally mediated syncope detected by carotid sinus massage and head-up tilt test in sick sinus syndrome

It is generally accepted that a positive response to carotid sinus massage (CSM) or head-up tilt (HUT) in patients affected by syncope suggests a reflex cause of the syncope. To study the role of the autonomic nervous system in causing syncope in the sick sinus syndrome (SSS), CSM and HUT were performed in 35 consecutive patients (20 men, mean age 70 +/- 9 years) with syncope and SSS. Results were compared with those in 35 patients affected by syncope that, despite careful cardiovascular and neurologic examination, were of uncertain origin (21 men; mean age 68 +/- 9 years) and with those of 35 subjects without syncope (20 men; mean age 69 +/- 10). All patients underwent CSM in the supine and standing positions for 10 seconds and HUT to 60 degrees for 60 minutes. In the patients with SSS, the full reproduction of spontaneous symptoms by CSM occurred in 21 (60%) and by HUT, in 19 (54%). At least 1 test was positive in 28 patients (80%): cardioinhibitory or mixed responses in 69%, vasodepressor responses in 11%. The percentages of positive tests in the patients with syncope of uncertain origin were similar to or slightly less than those of patients with SSS (CSM 63%, HUT 26%, overall 74%) with cardioinhibitory or mixed responses in 54% and vasodepressor in 20% (p less than 0.05). In control subjects, syncope was induced by CSM in 1 (3%) and by HUT in 2 (6%); overall positivity was 9%. In conclusion, in most patients affected by syncope and SSS, an abnormal neural reflex probably plays a major role in causing syncope.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduction of GH response to the GABA-B agonist baclofen in patients with major depression

In order to establish whether alterations in the GABAergic control of GH secretion occur in male patients with major depression, the GH response to the GABAergic-B agonist baclofen (10 mg at 0830h) or to placebo was tested in 9 depressed men and in 10 age- and weight-matched male normal controls.

The basal concentrations of GH were significantly lower in the depressed patients (0.87± 0.69 ng/ml) than in the normal controls (1.57±0.33 ng/ml) (p=0.011) and were not modified by the administration of placebo. The administration of baclofen induced a striking, significant increase in GH concentrations in the normal controls (mean peak at 90 MIN=6.4±1.5 ng/ml). In contrast, a slight, nonsignificant GH increase occurred in the depressed patients after baclofen (mean peak at 90 MIN=1.57±1.45 ng/ml). The GH response was significantly lower in the depressed than in the control subjects (p<0.001). These data indicate the presence of reduced GABAergic control of GH secretion in male depressed patients.     

Expansions and contractions of the FMR1 CGG repeat in 5,508 transmissions of normal,intermediate, and premutation alleles

Instability of the FMR1 repeat, commonly observed in transmissions of premutation alleles (55–200 repeats), is influenced by the size of the repeat, its internal structure and the sex of the transmitting parent. We assessed these three factors in unstable transmissions of 14/3,335 normal (~5 to 44 repeats), 54/293 intermediate (45–54 repeats), and 1561/1,880 premutation alleles. While most unstable transmissions led to expansions, contractions to smaller repeats were observed in all size classes. For normal alleles, instability was more frequent in paternal transmissions and in alleles with long 3′ uninterrupted repeat lengths. For premutation alleles, contractions also occurred more often in paternal than maternal transmissions and the frequency of paternal contractions increased linearly with repeat size. All paternal premutation allele contractions were transmitted as premutation alleles, but maternal premutation allele contractions were transmitted as premutation, intermediate, or normal alleles. The eight losses of AGG interruptions in the FMR1 repeat occurred exclusively in contractions of maternal premutation alleles. We propose a refined model of FMR1 repeat progression from normal to premutation size and suggest that most normal alleles without AGG interruptions are derived from contractions of maternal premutation alleles.     

The HLA-A,B gene frequencies in the world: Migration or selection?

Multivariate methods make it possible to condense much of the information available for a large number of alleles into one or a few synthetic variables. The geographic distribution of synthetic variables can be analyzed and plotted by the same technique used in analyzing and mapping the gene frequency of a single allele. The information contained in 21 HLA-A and HLA-B alleles from 116 world populations is condensed in principal components and discriminant functions which describe the global variation of gene frequencies along longitudes and along latitudes.

Most genetic variation is associated with longitude and shows a center of symmetry in Asia. Thus Asia, or some part of it, may have been the center, both geographically and historically of late Pleistocene migrations. However, latitude also plays a significant role (perhaps 10% of the genetic variation). A remarkable symmetry of the latitude variation in opposite (north and south) hemispheres suggests that climatic factors exercise selective pressure for certain HLA alleles. More specifically A1, A3, B7, B8, and B27 show about equally high correlation coefficients (between 0.45 and 0.55) with distance from equator. This results supports the idea that the well-known linkage disequilibria between A1 and B8, A3 and B7 are probably kept by selective pressure.     

Two-center collaborative evaluation of the performance of the BD Phoenix automated microbiology system for identification and antimicrobial susceptibility testing of Enterococcus spp. and Staphylococcus spp

The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, Md.) was assessed for identification (ID) and antimicrobial susceptibility testing (AST) for the majority of clinically encountered bacterial isolates in a European collaborative two-center trial. A total of 469 bacterial isolates of the genera Staphylococcus (275 isolates), Enterococcus (179 isolates), and Streptococcus (15 isolates, for ID only) were investigated; of these, 367 were single patient isolates, and 102 were challenge strains tested at one center. Sixty-four antimicrobial drugs were tested, including the following drug classes: aminoglycosides, beta-lactam antibiotics, beta-lactam-beta-lactamase inhibitors, carbapenems, cephems, folate antagonists, quinolones, glycopeptides, macrolides-lincosamides-streptogramin B (MLS), and others. Phoenix ID results were compared to those of the laboratories' routine ID systems (API 32 Staph, API 32 Strep, and VITEK 2 [bioMérieux, Marcy l'Etoile, France]); Phoenix AST results were compared to those of frozen standard broth microdilution (SBM) panels according to NCCLS guidelines (NCCLS document M 100-S 9, approved standard M 7-A 4). Discrepant results were repeated in duplicate. Concordant IDs of 97.1, 98.9, and 100% were observed for staphylococci, enterococci, and streptococci, respectively. For AST results the overall essential agreement was 93.3%; the category agreement was 97.3%; and the very major error rate, major error rate, and minor error rate were 1.2, 1.9, and 1.3%, respectively. In conclusion, the Phoenix ID results showed high agreement with results of the systems to which they were being compared; the AST performance was highly equivalent to that of the SBM reference method.     

Primary Immunodeficiency Syndrome in Spain: First Report of the National Registry in Children and Adults

The Spanish Registry for Primary Immunodeficiency Diseases (REDIP) was organized in 1993. One thousand sixty-nine cases of primary immunodeficiency diseases (PID) were registered in patients diagnosed between January 1980 and December 1995. PID diagnosis was made according to the World Health Organization criteria. The most frequent disorders were IgA deficiency (n = 394) and common variable immunodeficiency (n = 213), followed by severe combined immunodeficiency (n = 61), C1 inhibitor deficiency (n = 52), X-Iinked agammaglobulinemia (n = 49), IgG subclass deficiency (n = 48), and chronic granulomatous disease (n = 32). A comparative study between REDIP and data recently obtained from the European registry (ESID Report, 1995) revealed important differences between phagocytic disorders and complement deficiencies reported in both registries, 4.9 vs 8.7 and 6.0 vs 3.6, while percentages of predominantly antibody deficiencies and T cell and combined deficiencies concurred with those reported in the European registry, 69.3 vs 64.7 and 14.7 vs 20.2, respectively. The heterogeneous nature of the geographical distribution of cases submitted may indicate underdiagnosis of PID in some country areas; surprisingly, the interval between the onset of clinical symptoms and diagnosis was significant, even in immunodeficiency diseases, such as IgA deficiency, which are easy to diagnose.