Impact of acute psychosocial stress on attentional control in humans. A study of evoked potentials and pupillary response

Psychosocial stress has increased considerably in our modern lifestyle, affecting global mental health. Deficits in attentional control are cardinal features of stress disorders and pathological anxiety. Studies suggest that changes in the locus coeruleus-norepinephrine system could underlie the effects of stress on top-down attentional control. However, the impact of psychosocial stress on attentional processes and its underlying neural mechanisms are poorly understood. This study aims to investigate the effect of psychosocial stress on attentional processing and brain signatures. Evoked potentials and pupillary activity related to the oddball auditory paradigm were recorded before and after applying the Montreal Imaging Stress Task (MIST). Electrocardiogram (ECG), salivary cortisol, and subjective anxiety/stress levels were measured at different experimental periods. The control group experienced the same physical and cognitive effort but without the psychosocial stress component. The results showed that stressed subjects exhibited decreased P3a and P3b amplitude, pupil phasic response, and correct responses. On the other hand, they displayed an increase in Mismatch Negativity (MMN). N1 amplitude after MIST only decreased in the control group. We found that differences in P3b amplitude between the first and second oddball were significantly correlated with pupillary dilation and salivary cortisol levels. Our results suggest that under social-evaluative threat, basal activity of the coeruleus-norepinephrine system increases, enhancing alertness and decreasing voluntary attentional resources for the cognitive task. These findings contribute to understanding the neurobiological basis of attentional changes in pathologies associated with chronic psychosocial stress.

201Tl myocardial SPECT detects significant coronary artery disease between 50% and 75% angiogram stenosis

Coronary angiography is the "gold standard" for the diagnosis of coronary artery disease (CAD). The aim of this work was to compare 201Thallium SPECT with different coronary angiographic cutoff values.

METHODS

Data pertaining to 145 patients were tabulated. All patients underwent stress ECG, 201Thallium SPECT and coronary angiography. To assess the cutoff impact, two criteria for coronary angiography diagnosis were used: a) > or = 50% and b) > or = 75% stenosis, and applied to data from patients and vessels.

RESULTS

On a patient basis, 201Thallium SPECT sensitivity, specificity and accuracy were 87%, 57% and 81% with > or = 50% cutoff and 93%, 51% and 79% with > or = 75% cutoff, respectively (NS). When performing individual vessel analysis, sensitivity, specificity and accuracy were 59%, 78% and 68% for > or = 50% cutoff and 70%, 75% and 74% for > or = 75% cutoff, respectively (p < 0.029 for sensitivity). As expected, the severer the stenosis the higher the detection rate. There were 19 patients who had stenosis between 50% and 74%. Of these, 21% had abnormal stress ECG and 58% abnormal Thallium-201 SPECT.

CONCLUSION

201Thallium SPECT results support the use of > or = 50% stenosis cutoff criteria for CAD diagnosis and evaluation. Combined with coronary angiography, myocardial SPECT offers an excellent management strategy to patients.

X-ray absorptiometry of bone in obese and eutrophic children from Valparaiso, Chile

OBJECTIVE

To assess and compare bone mineral content (BMC) and bone mineral density (BMD) by dual X-ray absorptiometry (DEXA) measurement in obese and eutrophic children.

METHODS

In a cross sectional, case control study 16 obese children (8 male, 8 female) aged 5 to 13 years were recruited from the outpatient nutrition clinic of Carlos van Buren Hospital, Valparaiso, Chile, during 1997. Sixteen healthy eutrophic children matched for sex, chronological age, height, and pubertal stage were enrolled as controls. The mean dietary calcium intake was 580 +/- 100 mg/day. All obese patients had more than 2 standard deviation (SD) of height/weight ratio. Lumbar spine (L2-L4) BMD, femoral neck BMD, total body BMD, and total body BMC were measured by posteroanterior dual photon DEXA. The results were expressed as mean +/- SD. Comparison of the data was determined by Wilcoxon and Student t test.

RESULTS

Mean BMC was 1684.1 +/- 492.38 g in obese children and 1418.2 +/- 483.48 g in controls (p < 0.001, Student t test; p = 0.001, Wilcoxon test). Mean total BMD was 817.5 +/- 99.37 g/cm2 in obese children and 771.62 +/- 105.62 g/cm2 in controls. (p = 0.041 by Wilcoxon). Mean hip BMD was 784.4 +/- 117.05 g/cm2 in obese children and 801.67 +/- 150.34 g/cm2 in controls. Mean spine BMD was 724.87 +/- 171.75 g/cm2 in obese children and 686 +/- 137.08 g/cm2 in controls (not significant).

CONCLUSION

Obese children have more total body BMC than eutrophic children. There was no significant difference in regional hip BMD and lumbar spine BMD among obese and normal children. Obese children may have larger bones.

Is the addition of ECG gating to technetium-99m sestamibi SPET of value in the assessment of myocardial viability? An evaluation based on two-dimensional echocardiography following revascularization

The main goal of this study was to evaluate whether the addition of ECG gating to technetium-99m sestamibi single-photon emission tomographic (SPET) perfusion imaging assists the prediction of recovery of regional wall motion abnormalities after revascularization. Thirty-six patients with coronary artery disease were included in the study. All had wall motion abnormalities, and 31 (86%) had a clinical history of myocardial infarction. Coronary artery bypass surgery was performed in 18 patients and angioplasty in the remainder. All underwent ECG-gated and non-gated SPET at rest and after intravenous dipyridamole. Two-dimensional echocardiography was performed at a mean of 27 days before revascularization and at a mean of 69 days following revascularization to assess segmental wall motion changes. Perfusion prior to revascularization was analysed qualitatively and quantitatively on gated and non-gated SPET, and the results compared with those of echocardiography. Bullseye parameters were obtained from a normal database, generated from data in 40 normal volunteers, using dipyridamole ECG-gated and non-gated sestamibi SPET. There was good concordance between gated and non-gated qualitative analysis (79% with kappa=0.65) for normal, viable or necrotic segments. Gated SPET predicted functional recovery in 27 of 35 (77%) segments showing echocardiographic improvement while non-gated SPET did so in 30 of 39 (77%) such segments. Gated SPET predicted no functional recovery in 20 of 45 (44%) segments that did not show improved wall motion after revascularization, while with non-gated SPET the figure was 18 of 51 (35%). The positive predictive values of gated and non-gated SPET with regard to the recovery of wall motion following revascularization were 52% and 48%, while the negative predictive values were 71% and 67%, respectively. 99mTc-sestamibi had a low predictive value for recovery of function if visual assessment was used in the analysis of SPET data. Quantitative bullseye sestamibi parameters (defect extension and severity, reversibility and percentage change in extension), from gated or non-gated studies, appear best to distinguish which segments will display improved motility on the echocardiogram after revascularization. The addition of ECG gating does not significantly increase the predictive value of SPET imaging with regard to recovery of function.

Clinical and serological identification of 2 forms of complete heart block in children

OBJECTIVE

To study the association of maternal antibodies to Ro(SSA) and/or La(SSB) with isolated complete congenital heart block (CCHB) in children according to the child's age at detection.

METHODS

Sera from 17 mothers of 18 children with CCHB of unidentified cause were studied. Autoantibodies were measured by double immunodiffusion, enzyme linked immunosorbent assay (ELISA), Western blot, and immunoprecipitation from cell extracts. Statistical analysis used the chi 2 test with Yates' correction.

RESULTS

CCHB was diagnosed in 12 children of 11 mothers before the age of 3 mo (Group A) and in 6 children of 6 mothers after the age of 17 mo (Group B). Seven Group A mothers and no Group B mother had connective tissue disorders; autoantibodies were found in 9/11 Group A and in 1/6 Group B mothers (p < 0.01). Eight Group A children needed a pacemaker and one other died of cardiac insufficiency, whereas only one of the 6 Group B children needed a pacemaker. Interestingly, this latter child was the only one from Group B whose mother's serum contained autoantibodies. Irrespective of their age at diagnosis, the children with CCHB who needed a pacemaker and the one who died were born to mothers with autoantibodies (p < 0.001).

CONCLUSION

CCHB detected before the age of 3 mo is highly associated with the presence of anti-Ro(SSA)/La(SSB) in the mothers, while CCHB diagnosed later is generally not. For epidemiological studies, the former type should be considered early onset as opposed to late onset CCHB in the latter type. Establishing this clinicoserological distinction is also important for the children, since it alerts the clinician to a more severe prognosis (necessity of a pacemaker), even in the rare occurrence of late diagnosed CCHB.

[Tomographic myocardial perfusion (SPECT) using 99mTc sestamibi-dipyridamole and 2-d-echocardiography with amrinone pre and post myocardial revascularization in 2 cases]

We report two male patients aged 50 and 55 years old with coronary artery disease who were treated with surgical revascularization and angioplasty respectively. To assess viable and ischemic myocardial territories, they were studied before and after revascularization with radionuclide perfusion SPECT with Tc99m-Sestamibi under Dipyridamole and with 2-D echocardiography at baseline and after the use of amrinone. Improvement in relative perfusion on SPECT and wall motion on 2-D echocardiography indicated tissue recovery.

X-ray bone densitometry in the diagnosis and followup of reflex sympathetic dystrophy syndrome

OBJECTIVE

To establish bone involvement in reflex sympathetic dystrophy syndrome (RSDS).

METHODS

Bone mineral density (BMD g/cm2) and bone mineral content (BMC g) were measured by dual X-ray absorptiometry. We studied 12 patients with phase I RSDS and 18 controls.

RESULTS

BMD and BMC were significantly lower in the involved side of patients (28.4 and 45.1%, respectively) compared with the contralateral normal limb. Controls only showed a minimal variation of 2.17% in BMD and 4.38% in BMC between right and left measures. The difference between patients and controls was highly significant (p < 0.001). A second measurement of BMD and BMC was made in 8 patients following treatment (prednisone or calcitonin) and showed increments in both variables, which was significant in the affected limbs (20.1%).

CONCLUSION

We believe that X-ray bone densitometry is a highly sensitive and specific technique to evaluate bone mass in patients with RSDS and aid in diagnosis and treatment monitoring.

[Etodolac versus piroxicam in the treatment of acute lumbago. Double-blind study]

To evaluate the efficacy of the nonsteroidal anti-inflammatory drug etodolac, a comparative, double-blind study versus piroxicam was carried out. Two homogenous groups (in terms of age, sex, time since last crisis and duration of present episode) of patients suffering from acute lumbar pain were treated during one week with either etodolaco, 300 mg b.i.d. (n = 30) or piroxicam 20 mg/day plus placebo (n = 31). Diagnosis was confirmed by history, physical examination, and Rx studies. Several clinical parameters were assessed prior and after treatment. All 61 patients completed the study. Adverse drug reactions were evaluated in the final visit. No significant differences were established between groups in relation to efficacy. Compared to baseline, statistically significant relief of symptoms was achieved in both groups, for pain intensity (p < 0.005); sleep quality (p < 0.005); paravertebral muscles spasm (p < 0.005) and spinal range of motion (p < 0.005). Patients treated with etodolac exhibited significantly less adverse reactions than those on piroxicam (p < 0.025).

[Antimicrobial activity of orthodontic band cements]

The prevalence of enamel decalcification and caries beneath orthodontic bands, has indicated the need for a new enamel binding adhesive orthodontic cement. The purpose of this study was to evaluate the antimicrobial activity, in vitro, on Streptococcus mutans and Lactobacillus, acidophillus, of three materials used to cements the orthodontic bands. The cements studied were: Zinc phosphate cement, Glass-ionomer cement, and Policarboxylate cement. Thirty petri plates were seeded with S. mutans, and thirty with L. acidophillus; on each plate three pellet were placed, one of each cement studied. Petri plates were incubated under microaerophilic conditions at 37 C, and checked at 72 hrs. for Streptococcus, mutans, and four days for Lactobacillus acidophillus to evaluate the inhibition zone. The results were tabulated for each material. It was demonstrated that exists important variations in the antimicrobial properties of the materials studied, as in the microbial sensitivity to these cements.