High prevalence of vitamin D insufficiency in healthy elderly people living at home in Argentina.

OBJECTIVE: To evaluate the nutritional status of vitamin D in urban populations of healthy elderly people living at home, in different regions of Argentina. DESIGN: Cross-sectional study. SUBJECTS: In total, 386 ambulatory subjects over 65 y of age from seven cities (between latitude 26 degrees S and 55 degrees S) were asked to participate between the end of winter and the beginning of spring. Of these, 369 accepted, 30 were excluded because of medical history or abnormal biochemical determinations. Finally, 339 subjects (226 women and 113 men) (X+/-s.d.) (71.3+/- 5.2 y) were included. RESULTS: Serum 25OHD levels were lowest in the South (latitude range: 41 degrees S-55 degrees S): 14.2+/-5.6 ng/ml (P<0.0001vs North and Mid regions); highest in the North (26 degrees S-27 degrees S): 20.7+/-7.4 ng/ml (P<0.03 vs Mid, P<0.0001vs South); and intermediate in the Mid region (33 degrees S-34 degrees S) 17.9+/-8.2 ng/ml. Serum mid-molecule PTH (mmPTH) and 25OHD were inversely related: (r=-0.24, P<0.001). A cutoff level of 25OHD at which serum mmPTH levels began to increase was established at 27 ng/ml. A high prevalence (87-52%) of subjects with 25OHD levels in the deficiency-insufficiency range (25OHD levels <20 ng/ml) was detected. CONCLUSION: This study shows that vitamin D deficiency/insufficiency in the elderly is a worldwide problem. Correction of this deficit would have a positive impact on bone health of elderly people.

Peripheral bone mass is not affected by winter vitamin D deficiency in children and young adults from Ushuaia.

Low vitamin D levels in elderly people are associated with reduced bone mass, secondary hyperparathyroidism, and increased fracture risk. Its effect on the growing skeleton is not well known. The aim of this study was to evaluate the possible influence of chronic winter vitamin D deficiency and higher winter parathyroid hormone (PTH) levels on bone mass in prepubertal children and young adults. The study was carried out in male and female Caucasian subjects. A total of 163 prepubertal children (X age +/- 1 SD: 8.9 +/- 0.7 years) and 234 young adults (22.9 +/- 3.6 years) who had never received vitamin D supplementation were recruited from two areas in Argentina: (1)Ushuaia (55 degrees South latitude), where the population is known to have low winter 25OHD levels and higher levels of PTH in winter than in summer, and (2)Buenos Aires (34 degrees S), where ultraviolet (UV) radiation and vitamin D nutritional status in the population are adequate all year round. Bone mineral content (BMC) and bone mineral density (BMD) of the ultradistal and distal radius were measured in the young adults. Only distal radius measurements were taken in the children. Similar results were obtained in age-sex matched groups from both areas. The only results showing significant difference corresponded to comparison among the Ushuaian women: those whose calcium (Ca) intake was below 800 mg/day presented lower BMD and BMC values than those whose Ca intake was above that level (0.469 +/- 0.046 versus 0.498 +/- 0.041 g/cm(2), P < 0.02; 3.131 +/- 0.367 versus 3.339 +/- 0.386 g, P < 0.05, respectively). In conclusion, peripheral BMD and BMC were similar in children and young adults from Ushuaia and Buenos Aires in spite of the previously documented difference between both areas regarding UV radiation and winter vitamin D status. BMD of axial skeletal areas as well the concomitant effect of a low Ca diet and vitamin D deficiency on the growing skeleton should be studied further.

1,2-Diacetals in synthesis: total synthesis of a glycosylphosphatidylinositol anchor of Trypanosoma brucei.

A full account on a total synthesis of GPI anchor 1 employing butanediacetal (BDA) groups and a chiral bis(dihydropyran) is presented. The reactivity of selenium and thio glycosides was tuned by the use of BDA groups. This allowed the assembly of an appropriately protected GPI anchor precursor 2 in just six steps from the six building blocks 5-10 including only one protecting group manipulation. myo-Inositol was desymmetrised with the bis(dihydropyran) derivative 15 and appropriately protected to give inositol acceptor 21 in nine steps and 17% overall yield. The use of common starting materials and BDA-protections give efficient access to building blocks 5, 6, 7 and 8. A new and improved synthesis of the glucosamine donor 28 is included. In summary, a highly convergent and efficient synthesis of GPI anchor 1, which is clearly adaptable to other GPI anchors, has been reported.

[Carotid sinus hypersensitivity. Medium and long-term development in patients treated by ventricular pacing]. / Hypersensibilité sino-carotidienne. Evolution à moyen et à long terme des patients traités par stimulation ventriculaire.

The problem of pacing patients with carotid sinus hypersensitivity (CSH) is the choice and criteria of selection of the pacing mode. The authors studied 29 patients with CSH treated by VVI pacing over a period of 10 years. The average follow-up was 34 months (range 6 to 96 months). Three of the 27 patients (11%) who were asymptomatic at the outset continued to have symptoms. The nature of the CSH was well-defined in 25 patients; 19 of the 20 cases of cardio-inhibitory CSH and 4 of the 5 cases of mixed CSH were asymptomatic. These two poor clinical results were analysed: the patient with the cardio-inhibitory CSH (one recurrence in 84 months) had a drop of 40 mmHg in systolic blood pressure which fulfilled criteria of the cardio-inhibitory form of CSH (a drop of 30 to 50 mmHg). The second case was a complete therapeutic failure with 3 recurrent syncopal episodes. The patient had a mixed form of CSH (B.P. drop of 65 mmHg) associated with a "pace maker syndrome" (drop of 50 mmHg in systolic blood pressure at the onset of VVI pacing without any sino carotid massage). The authors conclude that the cases of CSH which, during their investigation, are best corrected by dual-chamber pacing or which are associated with a significant pacemaker effect or present retrograde ventriculo-atrial conduction, should receive dual-chamber pacemakers.

[Electrophysiological study of pro-arrhythmogenic effects of erythromycin]. / Etude électrophysiologique des effets pro-arythmogènes de l'érythromycine.

Three cases of torsades de pointe induced by erythromycin have recently been reported. After observing a new case, the authors tried to demonstrate the possible mechanism of the arrhythmogenic action of this molecule. Twenty-two patients undergoing electrophysiological studies in the catheter laboratory to determine the cause of syncope were given an intravenous injection of 10 mg/Kg of erythromycin lactobionate. The drug was injected in 1 minute (bolus) in 11 patients (Group A). The other 11 patients (Group B) received the drug by slow intravenous infusion (20 minutes). Electrophysiological parameters were measured before and after erythromycin. A significant prolongation of the atrial refractory periods (+39 ms), ventricular refractory periods (+20 ms), QT (+20 ms) and QTC intervals (+42 ms) was observed in Group A. These electrophysiological effects could explain an arrhythmogenic action similar to that of antiarrhythmic drugs in Group I of Vaughan-Williams' classification. The slow intravenous infusion of erythromycin in Group B considerably reduced these undesirable secondary effects. This difference was directly related to serum concentrations of the molecule.