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Biomedical subjects

J Santamaria

Publications and source records attributed to J Santamaria.

At least 19 recordsLinked to original sources
PubMed2001

Origin of constant loss in ionic conductors.

We have analyzed the constant loss contribution to the ac conductivity in the frequency range 10 Hz-1 MHz and temperatures down to 8 K, for two Li ionic conductors, one crystalline (Li(0.18)La(0.61)TiO(3)) and the other glassy (61SiO(2);35Li(2)O.3Al(2)O3.P(2)O(5)). As temperature is increased a crossover is observed from a nearly constant loss to a fractional power law frequency dependence of the ac conductivity. At any fixed frequency omega, this crossover occurs at a temperature T such that omega approximately nu(0)exp(-E(m)/k(B)T), where nu(0) is the attempt frequency and E(m) is identified with the barrier for Li+ ions to leave their wells.

Journal Article↗
PubMed2001

Nonconvulsive status epilepticus associated with cephalosporins in patients with renal failure.

PURPOSE: Nonconvulsive status epilepticus is an unusual complication of cephalosporin therapy, with only a few isolated cases reported. SUBJECTS AND METHODS: We reviewed the clinical and electroencephalographic (EEG) characteristics of 10 patients with renal failure in whom developed alteration of consciousness without convulsions associated with continuous epileptiform EEG activity while being treated with cephalosporins. RESULTS: Nonconvulsive status epilepticus developed in 5 men and 5 women, with a mean (+/- SD) age of 69 +/- 14 years, while receiving intravenous cephalosporins (ceftriaxone, 2 patients; ceftazidime, 2; and cefepime, 6). All patients had renal failure; 1 also had hepatic failure. Patients presented with progressive disorientation or agitation, sometimes associated with mild facial or limb myoclonus, that had begun 1 to 10 days (mean, 5 +/- 2 days) after starting cephalosporin treatment. The EEG showed continuous or intermittent bursts of generalized, high-voltage, 1 to 2 Hz sharp wave activity or sharp and slow wave activity that resembled, but could be differentiated from, the triphasic waves seen in metabolic encephalopathies. Intravenous clonazepam suppressed the epileptiform activity completely in 5 patients and partially in the other 5. Cephalosporins were withdrawn, and antiepileptic therapy was started for all patients. All patients improved, 2 in less than 24 hours and the remainder within 2 to 7 days. CONCLUSIONS: Cephalosporins can cause nonconvulsive status epilepticus in patients with renal failure. The clinical picture is difficult to differentiate from a that of metabolic encephalopathy unless an EEG is obtained. Physicians should be aware of this potentially dangerous complication.

Adult↗
PubMed2001

Nocturnal paroxysmal dystonia related to a prerolandic dysplasia.

Nocturnal paroxysmal dystonia (NPD) is a rare disorder characterized by attacks of short-lived dystonic, tonic and choreoatetoid movements occurring mainly during sleep. Although seizures are believed to arise from the frontal lobe, their localization is, however, uncertain due to the lack of ictal clinical-EEG correlations. Two patients are reported with episodes clinically compatible with NPD who also experienced occasional generalized tonic-clonic seizures in which there was a frontal (prerolandic) dysplasia detected by MRI. In one patient interictal/ictal SPECTs suggested that the seizure focus was over the area of dysplasia. Both patients support the notion that NPD is a type of epilepsy arising from the frontal lobe, possibly originating in the prerolandic region.

Adult↗
PubMed2001

Blood loss in elective coronary artery surgery: a comparison of centrifugal versus roller pump heads during cardiopulmonary bypass.

OBJECTIVES: To compare the effects of centrifugal pumps versus roller pumps for cardiopulmonary bypass (CPB) in routine cardiac surgery on hematologic parameters in the context of modern practice. DESIGN: Prospective, randomized, partially blinded. SETTING: University teaching hospital. PARTICIPANTS: Elective coronary artery surgery patients (n = 113) INTERVENTION: Patients were randomized to be perfused with either a roller head (group R, n = 56) or a centrifugal head (group C, n = 57) pump. Patients received epsilon-aminocaproic acid before and during CPB. Core body temperatures were allowed to drift down to approximately 32 degrees C. MEASUREMENTS AND MAIN RESULTS: Postoperative chest tube blood loss, blood product requirements, hemoglobin, and platelet counts were assessed. There were no significant differences in preoperative or intraoperative parameters, including CPB time, complexity of procedure, and minimum core temperature. There were the expected reductions in hemoglobin and platelet levels post-CPB in both groups to a similar extent. Chest tubes remained in situ for similar durations, and the final volume of drainage was not significantly different (group C, 1300 +/- 92 mL; group R 1117 +/- 83 mL; p = 0.14). Allogeneic blood was given to 23% of patients in group C and 18% in group R (p = 0.63). Aspirin was associated with an increase in early chest tube drainage. CONCLUSIONS: In this surgical and perfusion environment, the authors were unable to show an advantage, from the hematologic point of view, in the routine use of a centrifugal pump head in elective coronary artery surgical patients. The use of antifibrinolytic agents and mild hypothermia may have effects on hemostasis that overshadow the influence of pump head design in this type of surgery.

Aged↗
PubMed2001

Changes in hepatitis C-related liver disease in a large clinic population.

BACKGROUND: Hepatitis C virus (HCV) infection is a significant problem in the Australian community. Over the past few years, the number of patients with diagnosed hepatitis C has increased greatly. The aims of the present study were to define the clinical features of a large group of patients with chronic HCV infection and to examine changes occurring in the referral base and epidemiological characteristics of this group since analysis of the first 342 patients in 1994. METHODS: The study included 1,546 consecutive anti-HCV-positive patients who had been referred to St Vincent's Hospital from January 1990 to June 1998. Clinical and laboratory data were collected on all patients. RESULTS: Referrals from general practitioners increased from 31% to 70% of all patients between 1990-1993 and 1994-1998. A history of injecting drug use (IDU) was present in 64% of the patients. While 89% of the IDU group was Australasian born, 49% of those in the sporadic group were born overseas. Cirrhosis was found in 18% of biopsied patients. Age, infection duration, age at infection, Mediterranean or Asian origin and a history of transfusion or lack of HCV risk factors were associated with cirrhosis on univariate analysis. Patient age was the only independent predictor of cirrhosis. CONCLUSION: The majority of patients with HCV are diagnosed in general practice. A risk factor for infection is identified in 82% of patients. While our reported prevalence of cirrhosis may be an overestimate of that in the overall HCV community, the ultimate disease burden is likely to be significant.

Adult↗
PubMed2000

Selective excitation of vibrational states by shaping of light-induced potentials

In this Letter we describe a method for population transfer using intense, ultrafast laser pulses. The selectivity is accomplished by careful shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of pulses with proper frequency detunings and time delays. As an example, selective population transfer is demonstrated for a three-state model of the sodium dimer.

Journal Article↗
PubMed2000

Continuous positive air pressure eliminates nocturnal stridor in multiple system atrophy. Barcelona Multiple System Atrophy Study Group.

We prospectively studied the sleep patterns and laryngeal function of 20 patients with multiple system atrophy and found sleep disturbances in all subjects and vocal cord abduction dysfunction in 14 (70%). In three patients with nocturnal stridor and complete vocal cord abductor dysfunction, continuous positive airways pressure eliminated laryngeal stridor, obstructive apnoea, and haemoglobin desaturation.

Female↗
PubMed2000

No evidence of linkage to 6p markers in spanish families with juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is a common subtype of hereditary generalized epilepsy with an uncertain pattern of inheritance. Different studies in multiple families have provided evidence for and against linkage of the disease to chromosome 6p. We performed linkage analysis using microsatellite markers from 6p (D6S109, D6S248, D6S291, D6S426, D6S272, D6S466, D6S294, D6S257) and from centromeric 6q region (D6S402) in seven small families of Spanish origin. The highest LOD scores were obtained under an autosomal dominant inheritance model with a penetrance of 70% but a significant positive LOD score (Z>3) was not reached. LOD scores<-2 were obtained at different markers in three of our families. These results support the concept of genetic heterogeneity in the disease.

Adult↗
PubMed2000

Unilateral thalamic stroke does not decrease ipsilateral sleep spindles.

STUDY OBJECTIVES: To measure the sleep spindle characteristics in patients with unilateral thalamic stroke. DESIGN: A prospective study of patients with thalamic stroke and age-matched healthy controls. SETTING: Department of Neurology of a University Hospital. PARTICIPANTS: Thirteen patients (mean age: 67 years, SD: 13,44) with an isolated, unilateral acute thalamic stroke and 18 healthy age-matched volunteers. INTERVENTIONS: A polysomnogram recording from 14 scalp EEG electrodes performed during 2 consecutive nights, the second or third week after the stroke. Only the sleep of the second night was analyzed. MEASUREMENTS AND RESULTS: Sleep spindles were counted during two separate 10-minute epochs of stage II. Spindles appearing synchronously in both sides with similar amplitude were called "bilateral." Spindles with twice the amplitude in one side than the other were "right" or "left-side predominant". There were 8 patients with posterolateral, 3 with global and 2 with anterior lesions. Eight were right and 5 left-sided. The number of spindles was similar in patients (39.8 +/- 23.4 in 20 minutes) than controls (26.07 +/- 29.07; p=0.173). Spindles with a centroparietal (34%) and centroparieto-occipital localization (22%) were the most frequent. In controls approximately 66% of the spindles had a bilateral and symmetric distribution over the scalp, 23% of the spindles were predominantly left-sided and 5% were predominantly right-sided. In patients, bilateral spindles decreased (p<0.0001) but asymmetric spindles did not change. CONCLUSION: Unilateral acute thalamic stroke does not decrease sleep spindles ipsilaterally; rather, it seems to produce a bilateral diminution in their number.

Adult↗
PubMed2000

An investigation of the early effects of manual lung hyperinflation in critically ill patients.

This prospective within-group multicentre study was designed to assess the safety and short-term effectiveness of manual lung hyperinflation in mechanically ventilated patients. Eighteen patients from the intensive care units of two tertiary institutions were included and acted as their own control. Manual lung hyperinflation treatment involved patient positioning (side-lying), suctioning and manual lung hyperinflation. Side-lying treatment involved patient positioning and suctioning alone. Patients received both treatments on the day of data collection. Results demonstrated significant improvement for static respiratory system compliance (P = 0.001) with manual lung hyperinflation treatment compared to side-lying treatment. Manual lung hyperinflation treatment also cleared a significantly greater wet weight of sputum (P = 0.039). There were no differences between manual lung hyperinflation and side-lying treatment for gas exchange (PaO2/FIO2 and PaCO2), mean arterial pressure or heart rate. In conclusion, total static respiratory system compliance and sputum clearance were improved by the addition of manual hyperinflation to a physiotherapy treatment of positioning and suctioning in mechanically ventilated patients without compromise to cardiovascular stability or gas exchange.

Adult↗
PubMed1999

Hyperkalemic periodic paralysis associated with multiple sleep onset REM periods.

A 24-year-old man with sporadic hyperkalemic periodic paralysis (HPP) presented with moderate excessive daytime sleepiness and transitory episodes of weakness which occurred during and after sleep. Multiple sleep latency test (MSLT) demonstrated the presence of five sleep onset REM periods (SOREMPs) and a sleep latency of five minutes. Treatment with a diuretic which decreases serum potassium resolved all the clinical symtomps and a new MSLT showed the absence of SOREMPs and a sleep latency of 13.5 minutes. To our knowledge, the patient herein reported is the first case that associates sleep abnormalities and multiple SOREMPs with HPP. Furthermore, the present case suggests that SOREMPs may be explained by an increased extracellular potassium conductance related to HPP.

Adult↗
PubMed1998

Immunohistochemical localization of neurotrophins and neurotrophin receptors in human and mouse salivary glands.

This study was undertaken to analyze the occurrence of low- (p75) and high-affinity (TrkA, TrkB and TrkC) neurotrophin receptor proteins in human and mouse salivary glands using immunohistochemistry. Furthermore, the presence of neurotrophins was also investigated. The study was carried out on 14 human (4 parotid, 6 submandibular and 4 sublingual glands) and 5 mouse salivary glands, using polyclonal antibodies against Trk proteins. The intensity of immunostaining was calculated automatically and evaluated in arbitrary units of grey levels. In human tissues no immunoreactivity (IR) for the assessed antigens was observed in the serous or mucous acinar cells, although TrkA IR was found in the acini of the submandibular gland. The cells of the intercalated ducts showed p75 IR (sublingual) and TrkA IR (parotid gland). The striated and excretory ducts displayed p75 IR, TrkA IR and TrkC IR in all glands, but TrkB IR was never detected. No neurotrophins were detected. In the mouse glands the ductal cells display IR for p75 (submandibular) and Trks A and C (parotid and submandibular) but not the sublingual gland. Acinar cells of the submandibular gland also show p75 IR. The only neurotrophin found in the mouse salivary glands was NGF (submandibular gland). These results suggest that neurotrophins may be involved in controlling the physiology of epithelial salivary cells.

Animals↗
PubMed1997

Radiologic variables of clinical significance in the extraction of impacted mandibular third molars.

OBJECTIVE: To determine which radiologic variables have a clinical significance in the extraction of impacted mandibular third molars. STUDY DESIGN: A prospective study was carried out on 100 consecutive extractions of unilateral impacted mandibular third molars (60 women and 40 men, mean age: 26.27 +/- 10.63 years). Fourteen radiologic variables were ordinally evaluated, establishing their relation to the surgical intervention time. The Kruskal-Wallis test, a multivariant analysis of the principal components, the Pearson correlation coefficient, and logistical regression tests were carried out. RESULTS: Seven variables (occlusal plane, relation to the second molar, depth, follicle, periodontal ligament width, ramus of the mandible, and angulation) demonstrated a statistically significant relation to the surgical intervention time (Kruskal-Wallis tests, p < 0.007). Two associated variables, depth and periodontal ligament width, showed the most powerful and simple relation to the surgical intervention time (r2 multiple = 0.307, p < 0.001). CONCLUSION: The model we propose is a tool that may help the general practitioner to establish competence in an extraction of the impacted mandibular third molar by measuring the association of two radiologic variables: depth and periodontal ligament width.

Adolescent↗
PubMed1997

What is the relationship between arachnoid cysts and seizure foci?

PURPOSE: Arachnoid cysts are sometimes encountered in MRIs performed for a variety of reasons. In patients with epilepsy, particularly those with refractory epilepsy, arachnoid cysts are often assumed to be related to their seizure focus. We conducted a study to investigate this putative relationship. METHODS: A retrospective study on the incidence of arachnoid cysts was performed in patients seen in our Epilepsy Clinic who had CT or MRI scans, interictal EEGs or ictal EEGS. Locations of seizure foci in these patients were defined from clinical and electrophysiologic data. RESULTS: Seventeen of 867 patients had arachnoid cysts. Twelve patients had temporal lobe cysts and only 3 of them had temporal lobe seizures. Four patients had frontal lobe cysts and only 1 had frontal lobe seizures ipsilateral to the cyst. One patient had a cerebello-pontine angle cyst and frontal lobe seizures. Thus, clinical manifestations of seizures and EEG findings (interictal and/or ictal) indicated that the seizure focus was adjacent to the cysts in only 4 patients (23.5%). CONCLUSIONS: Our findings suggest that arachnoid cysts are often an incidental finding in patients with epilepsy and do not necessarily reflect the location of the seizure focus.

Adolescent↗
PubMed1996

Mercury distribution and renal metallothionein induction after subchronic oral exposure in rats.

The effects of long-term daily intake of low and high levels of mercury on its organ distribution and binding to renal metallothionein (MT) in male rats were studied. The animals were exposed to mercuric chloride labelled with 203Hg via drinking water for 8 weeks (5, 50 and 500 microM Hg). The greatest concentration of mercury was found in the kidneys. Similar levels of radioactivity in the buccal cavity and oesophagus were also observed by whole-body autoradiography. In the kidneys, the mercury was accumulated in the outer stripe of the outer zone of the medulla and, to a minor degree, in the renal cortex. Almost 50% the total renal mercury was associated to MT. The binding capacity of the renal MT for mercury tends to saturate with increasing doses, thus this means that the capacity of the kidneys to accumulate mercury is limited.

Administration, Oral↗