Identification of a Drosophila presenilin homologue: evidence of alternatively spliced forms

Some cases of Alzheimer's disease are inherited as a dominant trait in humans. To date, mutations in three genes account for some of them: the amyloid precursor protein (APP) and presenilins 1 and 2 (PS-1 and PS-2, respectively). The function of the presenilins is still unclear, although they belong to a transmembrane protein-gene family, probably involved in some signaling pathway. We report here the isolation of the Drosophila presenilin homologue using the human PS-1 and PS-2 cDNAs as probes. Only one single gene has been detected in the Drosophila genome and evidence for alternatively spliced forms is presented and compared to the isoforms reported in humans. Temporal and spatial expression has been assessed by Northern blot and in situ hybridization on embryos of different developmental stages.

Pseudohypertriglyceridaemia

A mistake can be made in interpreting plasma triglyceride levels since in some cases pseudohypertriglyceridaemia may result from increased plasma glycerol due to a glycerol kinase deficit. Most automated triglyceride assays used in laboratories do not contain a negative control, i.e. a glycerol assay. We report two cases with pseudohypertriglyceridaemia due to hyperglycerolaemia and describe the clinical and biological features which suggested the diagnosis.

Evolution of beta-amylase: patterns of variation and conservation in subfamily sequences in relation to parsimony mechanisms

Soybean and sweet potato beta-amylases are structured as alpha/beta barrels and the same kind of folding may account for all known beta-amylases. We provide a comprehensive analysis of both protein and DNA (coding region) sequences of beta-amylases. The aim of the study is to contribute to the knowledge of the evolutionary molecular relationships among all known beta-amylases. Our approach combines the identification of the putative eightfold structural core formed by beta-strands with a complete multi-alignment analysis of all known sequences. Comparing putative beta-amylase (alpha/beta)8 cores from plants and microorganisms, two differentiated versions of residues at the packing sites, and a unique set of eight identical residues at the C-terminal catalytical site are observed, indicating early evolutionary divergence and absence of localized three-dimensional evolution, respectively. A new analytical approach has been developed in order to work out conserved motifs for beta-amylases, mostly related with the enzyme activity. This approach appears useful as a new routine to find sets of motifs (each set being known as a fingerprint) in protein families. We demonstrate that the evolutionary mechanism for beta-amylases is a combination of parsimonious divergence at three distinguishable rates in relation to the functional signatures, the barrel scaffold, and alpha-helix-containing loops.

[Postoperative analgesia in herniated disk surgery. Comparative study of diclofenac , lysine acetylsalicylate, and ketorolac]

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in treating musculoskeletal pain and are theoretically ideal for treating postoperative pain of the lumbar column.

OBJECTIVES

To compare the analgesic efficacy and side effects of treatment with 3 NSAIDs (lysine acetylsalicylate, ketorolac and diclofenac) in the treatment of pain after surgery for lumbar disc hernia.

PATIENTS AND METHODS

We enrolled 75 ASA I-II patients undergoing discectomy because of lumbar disc hernia; balanced general anesthesia was used in all cases. The patients were randomly distributed in 3 groups based on type of analgesia given in the immediate postoperative period. Group A received lysine acetylsalicylate (1800 mg), group B received ketorolac (30 mg) and group C received diclofenac (75 mg). The analgesics were diluted in 100 mg of saline solution and administered through a peripheral vein over 10 min. We evaluated the analgesia attained on a visual analog scale (VAS) and the physiological response to pain was assessed by monitoring changes in arterial pressure, heart rate and breathing frequency. If analgesia was insufficient 30 min after administration of the drug, 200 mg of lysine cloximate was given as a top-up. The side effects of each drug were also recorded.

RESULTS

VAS evaluation showed significant reductions in pain 60 min after administration in groups A and B and after 120 min in group C. Nine patients in each group required lysine cloximate. There were no significant differences in physiological response among the 3 groups. No patient suffered major side effects. Mild side effects were reported most often in group B.

CONCLUSIONS

The NSAIDs studied were inadequately for treating pain after surgery for lumbar disc hernia. Ketorolac was no better than the other analgesics studied but was associated with a higher number of mild side effects.

[Intravenous anesthesia using propofol during lengthy neurosurgical interventions]

OBJECTIVE

To compare the hemodynamic stability and time to recovery of consciousness after long-duration (> 3 h) neurosurgery with 2 anesthetic protocols: total intravenous anesthesia with propofol as the single hypnotic agent and inhalational anesthesia with isoflurane.

PATIENTS AND METHOD

We studied 58 middle-aged patients (range 40-50 years) scheduled for intracranial surgery. The patients, who all scored over 13 on the Glasgow coma scale before surgery, were randomly divided into two groups: 27 in group I received isoflurane and 31 in group II received propofol. Anesthetic induction was with sodium thiopental 4 mg/kg i.v. in group I and with propofol 2.5 mg/kg i.v. in group II. Both groups then received fentanyl 2 micrograms/kg i.v., lidocaine 1.5 mg/kg i.v. and vecuronium 0.2 mg/kg i.v. Before placement of the Mayfield head grip, with clamps, or before start of surgery in those cases in which the head grip was not used, all patients were given a 3 micrograms/kg i.v. dose of fentanyl. Hypnosis was maintained in group I with concentrations of isoflurane that were adequate for keeping minimum alveolar concentration (MAC) between 0.6 and 1. In group II maintenance was by continuous i.v. perfusion of propofol 10 mg/kg/h for 30 min., followed by 8 mg/kg/h for 30 min. and 6 mg/kg/h until the end of surgery. N2O was never used.

RESULTS

After induction systolic and mean arterial pressures (SAP and MAP) decreased significantly in both groups in comparison with baseline values (SAP: 113.1 +/- 30.0 vs. 140.9 +/- 27.08 mmHg in group I and 109.6 +/- 22.1 vs. 135.0 +/- 19.7 mmHg in group II; MAP: 76.8 +/- 18.7 vs. 95.6 +/- 17.0 mmHg in group I and 74.9 +/- 13.2 vs. 93.4 +/- 13.7 mmHg in group II). The patients in group II showed less tendency to develop arterial hypertension in response to orotracheal intubation (SAP and MAP at the moment of intubation: 156.4 +/- 33.7 and 104.6 +/- 18.1 mmHg, respectively, in group I as compared to 135.1 +/- 31.2 and 93.5 +/- 22.4 mmHg in group II; p < 0.05 between the 2 groups and p < 0.05 for the baseline and intubation pressures in group I). Time to recovery of effective, spontaneous breathing was shorter in group I (5.9 +/- 4.9 and 8.9 +/- 5.7 min.) than in group II (10.9 +/- 9.6 and 13.0 +/- 7.4 min.) and tubes could be extracted earlier from patients in the isoflurane group (10.4 +/- 6.1 min. vs. 17.6 +/- 12.8 min.; p < 0.01). We found no differences between the 2 groups for time until eye opening, response to verbal orders or time until start of spontaneous movement.

CONCLUSIONS

Propofol can be considered an alternative to the traditional thiopental-isoflurane sequence in neurosurgery lasting more than 3 h. In our study the hypertensive response to the stimulus of orotracheal intubation was lower in the propofol group than in the thiopental-isoflurane group.

Right ventricular systolic time intervals determined by means of a pulmonary artery catheter

OBJECTIVES

To evaluate the right ventricular systolic time interval as an index of right ventricular function and also to ascertain whether the right ventricular ejection fraction may be determined by means of a conventional pulmonary artery catheter.

DESIGN

Prospective study.

SETTING

Intensive care unit.

PATIENTS

Eight, consecutive critically ill adult patients.

METHODS

Simultaneous blind measurements, performed by two investigators, of the right ventricular systolic time interval and right ventricular ejection fraction, determined by means of a pulmonary artery catheter. Two studies, separated by an interval of 24 hrs, per patient. Linear regression analysis. Multiple regression test.

RESULTS

Of the 16 studies performed, two determinations of right ventricular systolic time intervals were technically inadequate. In the remaining 14 valid studies, we found one close linear correlation between the right ventricular ejection fraction and the preejection period/ejection time quotient measured using the simultaneous display of the electrocardiogram (EKG) and pulmonary arterial pressure curve (r2 = .90, p < .001, right ventricular ejection fraction = 68.96-60.59 x [right ventricular preejection period/right ventricular ejection time]). The method proved to be simple, very accurate, with little interobserver variation (8.09 +/- 10.6% interobserver variation for right ventricular preejection period/right ventricular ejection time) and provided adequate information regarding situations in which the performance of the right ventricle is modified in a given patient. The right ventricular preejection period/right ventricular ejection time quotient was the only variable that displayed a significant relationship with the right ventricular ejection fraction in the multivariate analysis (p < .001).

CONCLUSIONS

Right ventricular systolic time intervals, measured using the simultaneous display of the pulmonary artery catheter curve and EKG, provide adequate information regarding right ventricle performance in critically ill patients. The close linear correlation between the right ventricular preejection period/right ventricular ejection time quotient and the right ventricular ejection fraction enables the investigator to estimate, with a high degree of accuracy, the right ventricular ejection fraction and the values derived from the preload of the right ventricle, without the need for a modified pulmonary artery catheter.

[Thrombosis of intrathoracic veins. A complication of venous catheterization for temporary hemodialysis]

Venous thrombosis of large vessels is a common complication, generally asymptomatic, that may occur during central venous catheterization for temporal hemodialysis. We report 2 cases of intrathoracic venous thrombosis which were suspected because of the difficulties occurring during catheterization of a new venous approach during dialysis. Both cases were diagnosed by angiography.