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Biomedical subjects

J Santamaria

Publications and source records attributed to J Santamaria.

At least 19 recordsLinked to original sources
PubMed2006

Interfacially controlled transient photoinduced superconductivity.

We report on a large transient photoinduced enhancement of the superconducting critical temperature (DeltaTc = 23 K) in epitaxial YBa2Cu3O(6.7)/La(0.7)Ca(0.3)MnO3 bilayers upon visible light illumination. The effect relaxes with a characteristic time of 100 s at low temperatures, which is 4 orders of magnitude faster than the persistent photoconductivity or persistent photoinduced superconductivity previously found in single high-Tc superconducting films. This result is discussed in terms of light induced charge transfer through the interface similar to what happens in semiconductor junctions.

Journal Article↗
PubMed2006

Unplanned admission to the intensive care unit in postoperative patients--an indicator of quality of anaesthetic care?

As a clinical indicator, unplanned admission to the Intensive Care Unit from the operating room has been thought to reflect the quality of anaesthesia care intraoperatively. To explore this concept, we examined all such admissions at three hospitals over a three-month period. Cases were classified according to the Victorian Consultative Council on Anaesthetic Mortality and Morbidity (VCCAMM) classification system and an assessment was made as to whether the admission was inevitable or not. Demographic data were collected as well as co-morbidities, severity of illness, length of stay, discharge functional status and destination. There were 165 admissions identified: 55.8% were male, the median age was 63.5 years (range 15-90). There were 24 in-hospital deaths: 151 patients suffered serious morbidity or mortality. In 32 patients (19.4%), the morbidity or mortality was considered at least partially anaesthetic-related, and in 20 (12.1%), under the control of the anaesthetist. There were 28 admissions (17.0%) with a further 9 anaesthetic-related admissions (5.5%) which were considered potentially avoidable. Avoidable anaesthetic-related admissions were due to drug overdosage (5 cases), drug error (1 case), problems relating to preoperative assessment (1 case), aspiration (1 case) and pulmonary oedema (1 case). These findings suggest that unplanned admission to the Intensive Care Unit from the operating room is not a satisfactory indicator of quality of care by the anaesthesia team. This indicator appears to represent mainly the surgical and medical conditions of the patients, and their complications. Only one in twenty unplanned admissions in this series were potentially avoidable due to complications of the anaesthetic or the postoperative analgesia.

APACHE↗
PubMed2006

[MM1 variant of sporadic Creutzfeldt-Jakob disease with long duration akinetic mutism state].

INTRODUCTION: When patients present with a characteristic clinical picture of Creutzfeldt-Jakob disease (CJD) associated with positive 14-3-3 assay, periodic sharp wave complexes, high-signal of the striatum on magnetic resonance imaging, and homozygosis methionine (M) in codon 129, the median survival is 4 to 6 months. CLINICAL CASE: We report a 58-year-old woman with these typical features who survived 21 months, 19 of them in an akinetic mutism state. The autopsy confirmed the diagnosis of the most common CJD phenotype (MM1), usually associated with a shorter survival, and demyleinitation of the white matter (panencephalopathic form). CONCLUSIONS: The MM1 variant of CJD, with a rapidly progressive course leading into an akinetic mutism shortly after disease onset can be followed by a long akinetic mutism state. This profile is suggestive of panencephalopathic form and should be taken into account when counselling about survival.

Akinetic Mutism↗
PubMed2005

Giant magnetoresistance in ferromagnet/superconductor superlattices.

We show magnetoresistance in excess of 1000% in trilayers containing highly spin-polarized La0.7Ca0.3MnO3 and high-Tc superconducting YBa2Cu3O7. This large magnetoresistance is reminiscent of the giant magnetoresistance (GMR) in metallic superlattices but with much larger values, and originates at spin imbalance due to the injection of spin-polarized carriers. Furthermore, in contrast to ordinary GMR, the magnetoresistance is intimately related to the superconductivity in the YBa2Cu3O7 layer and vanishes in the normal state. This result, aside from its fundamental importance, may be of interest for the design of novel spintronic devices based on ferromagnet/superconductor structures.

Journal Article↗
PubMed2005

Transport of microsporidium Encephalitozoon intestinales spores in sandy porous media.

The retention and transport of microsporidium Encephalitozoon intestinales spores in two water-saturated sandy porous media was investigated in this study. The initial breakthrough of the spores in the column effluent occurred essentially simultaneously with that of a non-reactive tracer, indicating no significant velocity enhancement. A large fraction (45-73%) of the spores injected into the columns was not recovered in the effluent, indicating removal from solution through colloid retention processes of attachment and/or straining. The relative significance of attachment and straining to total retention was evaluated in additional experiments. An experiment was conducted with a sieved coarse fraction of porous media for which straining is unlikely to be of significance based on the relative diameters of the spores and porous-medium pores. The spore recovery for this experiment was similar to the recoveries obtained for microsporidia transport in the un-sieved parent porous medium. An additional experiment was conducted with a subsample of the coarse fraction that was acid-washed to reduce potential surface attachment sites. Spore recovery was complete for this experiment. These results suggest surface deposition was the primary removal mechanism in our system. This conclusion is supported by the results of an experiment wherein deionized water was flushed through a column that was previously flushed with electrolyte solution. The effluent spore concentrations were observed to increase upon injection of deionized water, indicating re-mobilization of spores upon a change in water chemistry. The measured data were successfully simulated using a mathematical model incorporating colloid filtration. The results of this study suggest that the transport of microspordia in sandy porous media is governed by established colloid-transport processes.

Colloids↗
PubMed2005

Outcome-based clinical indicators for intensive care medicine.

The clinical indicator is a tool used to monitor the quality of health care. Its use in the Intensive Care Unit (ICU) is desirable for many reasons: the maintenance of minimum standards, the development of best practice and the delivery of cost-effective health care. The utility of clinical indicators in ICU is limited by the lack of universal, robust, transparent, evidence-based and risk-adjusted measures of quality, and the difficulties in defining "quality care" and "good outcome". Monitoring of adverse events, system descriptors, and resource indicators is valuable but they have a limited relationship to the quality of care. ICU mortality prediction models provide a global measure of quality and, despite their inherent deficiencies, remain one of the most robust and useful clinical indicators.

Benchmarking↗
PubMed2004

Long-term effect of CPAP in the treatment of nocturnal stridor in multiple system atrophy.

The authors found that continuous positive airway pressure (CPAP) eliminated video-polysomnographic documented stridor in 13 multiple system atrophy (MSA) subjects with vocal cord abnormalities. Long-term follow-up showed high CPAP tolerance, no recurrence of stridor, no major side effects, subjective improvement in sleep quality, and that median survival time was similar to a group of 26 MSA patients without stridor. This study shows that in MSA, CPAP is an effective noninvasive long-term therapy for nocturnal stridor.

Aged↗
PubMed2004

Sentinel node biopsy in head and neck cancer: preliminary results of a multicenter trial.

BACKGROUND: The aim was to determine the reliability and reproducibility of sentinel node biopsy (SNB) as a staging tool in head and neck squamous cell carcinoma (HNSCC) for T1/2 clinically N0 patients by means of a standardized technique. METHODS: Between June 1998 and June 2002, 227 SNB procedures have been performed in HNSCC cases at six centers. One hundred thirty-four T1/2 tumors of the oral cavity/oropharynx in clinically N0 patients were investigated with preoperative lymphoscintigraphy (LSG), intraoperative use of blue dye/gamma probe, and pathological evaluation with step serial sectioning and immunohistochemistry, with a follow-up of at least 12 months. In 79 cases SNB alone was used to stage the neck carcinoma, and in 55 cases SNB was used in combination with an elective neck dissection (END). RESULTS: In 125/134 cases (93%) a sentinel node was identified. Of 59 positive nodes, 57 were identified with the intraoperative gamma probe and 44 with blue dye. Upstaging of disease occurred in 42/125 cases (34%): with hematoxylin-eosin in 32/125 (26%) and with additional pathological staging in 10/93 (11%). The sensitivity of the technique with a mean follow-up of 24 months was 42/45 (93%). The identification of SNB for floor of mouth (FOM) tumors was 37/43 (86%), compared with 88/91 (97%) for other tumors. The sensitivity for FOM tumors was 12/15 (80%), compared with 30/30 (100%) for other tumor groups. CONCLUSION: SNB can be successfully applied to early T1/2 tumors of the oral cavity/oropharynx in a standardized fashion by centers worldwide. For the majority of these tumors the SNB technique can be used alone as a staging tool.

Carcinoma, Squamous Cell↗
PubMed2002

Scaling of the interface roughness in Fe-Cr superlattices: self-affine versus non-self-affine.

We have analyzed kinetic roughening in Fe-Cr superlattices by energy-filtered transmission electron microscopy. The direct access to individual interfaces provides both static and dynamic roughness exponents. We find an anomalous non-self-affine scaling of the interface roughness with a time dependent local roughness at short length scales. While the deposition conditions affect strongly the long-range dynamics, the anomalous short-range exponent remains unchanged. The different short- and long-range dynamics outline the importance of long-range interactions in kinetic roughening.

Journal Article↗
PubMed2002

Cytological and microbiological findings in guttural pouch lavages of clinically normal horses with head restraint.

OBJECTIVE: To evaluate the cytological and microbiological contents of guttural pouch washes of ten randomly selected horses restrained so as to prevent them lowering their heads, and to assess the possible effects on the guttural pouch environment in these horses. PROCEDURE: Cytological and microbiological studies were performed on guttural pouch washes of ten clinically normal horses restrained in a standing position so as to prevent them from lowering their heads below normal, as would happen during transportation on long journeys. They were restrained for 12 or 24 h and cytological, bacteriological and mycological findings in guttural pouch washes were recorded. RESULTS: The cytological gradings and neutrophil concentrations of guttural pouch washings were higher in horses that had their heads restrained for a longer period. Washings from these horses were more likely to contain cultivable bacteria and were the only washes yielding potentially pathogenic bacterial species. CONCLUSION: Variation in the cytological differential counts and bacterial cultures of guttural pouch lavages may be found in clinically normal horses which have had their heads restrained in an elevated position for periods from 12 to 24 h. This should be considered when examining this site and care must be taken when interpreting cytology of guttural pouch lavages in samples taken after transportation for more than 12 h. Restriction of head movement could also affect the normal pouch enviroment and predispose it to disease.

Animals↗
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↗