Impact of locking solutions on conditioning biofilm formation in tunnelled haemodialysis catheters and inflammatory response activation

INTRODUCTION

The surface of tunnelled cuffed catheters provides an optimal environment for the development of biofilms, which have recently been described as conditioning films because of the presence of adherent biological materials. These biofilms are associated with infection and thrombosis and potentially increase patients' inflammatory response. These complications could be reduced by the use of locking solutions.

OBJECTIVE

To analyse biofilm formation, using confocal and electron microscopy, in tunnelled cuffed catheters locked with three different solutions and to determine the relationship between these solutions and inflammatory response.

STUDY DESIGN

This prospective study included 35 haemodialysis patients with tunnelled cuffed catheter removal for non-infection-related reasons. The participants were divided into three groups according to the lock solution used: (1) heparin 1: 5000 IU; (2) citrate 4%; and (3) taurolidine 1.35%, citrate 4% and heparin 500 IU (taurolock); in the latter group, 25,000 IU taurolidine-urokinase was used in the last weekly session. All tunnelled cuffed catheters were cultured, and the inner surface was evaluated with confocal and electron microscopy. The inflammatory profile of included patients was determined at tunnelled cuffed catheter removal.

RESULTS

There were no differences in clinical or demographic variables between the three subgroups. Biofilm thickness was lower in the taurolidine group than in the citrate 4% and heparin groups (28.85 ± 6.86 vs 49.99 ± 16.56 vs 56.2 ± 15.67 µm, respectively; p < 0.001), as was biofilm volume (1.01 ±1.18 vs 3.7 ± 2.15 vs 5.55 ±2.44, µm³, respectively; p < 0.001). The mean interleukin-6 value was 39%, which was 50% lower than in the citrate and heparin groups, but without significance differences.

CONCLUSION

Our results show that biofilms were found in all tunnelled cuffed catheters, but the thickness and volume were significantly lower in tunnelled cuffed catheters locked with taurolidine solution. Therefore, the type of locking solution used in tunnelled cuffed catheters should maintain tunnelled cuffed catheter sterility and prevent catheter-related bloodstream infections. No significant difference was observed in the inflammatory profile according to the type of locking solution.

Gallium-assisted growth of silicon nanowires by electron cyclotron resonance plasmas

The use of gallium droplets for growing Si nanowires (SiNWs) by electron cyclotron resonance plasmas is investigated. First, the relationship between evaporation time and resultant size of the gallium droplets is studied. Through the use of spectroscopic ellipsometry, the dependence of the surface plasmon resonance (SPR) energy on the droplet size is determined. From these gallium droplets, SiNWs were grown at 300 and 550 °C in electron cyclotron resonance plasmas containing SiH(4), Ar, and H(2). Scanning electron microscopy results show that tapered NWs are obtained for a wide range of growth conditions. Besides, it is found that H(2) plays an important role in the parasitic axial growth of the SiNWs. Namely, H(2) inhibits the radial growth and contributes dramatically to increasing the SiNW defects.

[Evaluation of a workplace anti-smoking program at a company with 640 employees]

OBJECTIVES

Awareness of the health risks of passive smoking for non-smokers has led to the development of workplace interventions for smokers, although they are still few in our setting. The objective of this study was to evaluate the efficacy of an anti-smoking program among the workers of a company, in function of changes in the pre- and post-intervention prevalence of smoking in the study population.

METHOD

A pre-intervention questionnaire on smoking (prevalence and attitudes) was administered at a company with 640 employees (92% men, 8% women). An anti-smoking program was carried out inside the company during working hours over the next nine months. The questionnaire was then repeated (post-intervention) in order to evaluate its efficacy based on changes. For employees who answered both questionnaires, paired variables were analyzed.

RESULTS

The pre-intervention questionnaire was answered by 388 employees (60%), 357 men (92%) and 31 women (8%); their mean age was 48.4 years (SD 9.36). The prevalence of smoking was 55%, including daily smokers, sporadic smokers and others. The mean number of cigarettes per day was 17.86 (SD 2.45). The mean level of nicotine dependence measured by the Fagerström test was 3.3 (SD 2.8) out of 10. The post-intervention questionnaire was answered by 206 employees (32%). Among employees who answered both questionnaires (83), analysis of paired data showed a decrease in the prevalence of smoking of 4% and in the number of cigarettes per day from 17.4 (pre-intervention) to 16.4 (post-intervention). The differences were not statistically significant.

CONCLUSIONS

Although the workplace is an appropriate setting for anti-smoking interventions that would contribute to improving the health of smokers, such programs are currently underutilized.

A time-dependent expression for thixotropic areas. Application to aerosil 200 hydrogels

Experimental determination of the areas enclosed under the up curve, sigma = sigma(;gamma), corresponding to time zero, and the down curve, which would be obtained following complete rheodestruction of the system structure, is not an easy matter. In the present study a semi-empirical procedure for calculating the hypothetical values of these parameters is proposed. With these parameters it is possible to obtain a time-dependent expression for the thixotropic areas, S(T). This procedure has been applied to the study of the thixotropic behavior of Aerosil 200 hydrogels at different concentrations. The comparative analysis of these systems has been realized by studying the relative thixotropic areas and relative thixotropic rates that are obtained from S(T).

Diagnostic approach to patients with suspected pulmonary embolism: a report from the real world

This study was carried out to examine the diagnostic approach to patients with suspected pulmonary embolism (PE) in a university hospital. A retrospective case record review of 251 patients with suspected pulmonary embolism was carried out according to a standard protocol, which looked at the utilisation of imaging techniques and compared clinical diagnoses with a standardised diagnosis established according to current recommendations. Isotopic lung scan was the most commonly used technique (73%), followed by leg vein sonography (36%) and contrast venography (31%). Lung arteriography was done in only 7% of patients. Among the 205 patients with a clinical diagnosis of PE, 115 (56%) would be diagnosed as having PE according to the standard criteria, 84 (41%) would be unclassified, and six (3%) would not be regarded as having PE. Among patients who were diagnosed as having PE and received anticoagulant therapy, 32% did not have the diagnosis confirmed by an imaging technique. Most of these had a non-diagnostic lung scan which, despite evidence to the contrary, seemed to be interpreted as confirmation of PE. We conclude that clinicians do not seem to follow current recommendations when approaching patients with suspected PE. In particular, there is an over-reliance on lung scans, and the significance of non-diagnostic scans was often misinterpreted. Arteriography was underused. These results emphasise the need to take measures to implement practice guidelines and to explore the usefulness of newer non-invasive techniques.

[Agreement in the clinical diagnosis of pulmonary embolism]

BACKGROUND

The diagnosis of pulmonary embolism (PE) may be a difficult task. The diagnostic performance of imaging techniques is limited and pre-test probability of PE, estimated from basic clinical data, must be taken into consideration to interpret their results. The aim of this study was to evaluate the accuracy and agreement of clinicians in estimating PE probability.

PATIENTS AND METHODS

We reviewed the charts of 116 patients admitted to hospital for suspected PE. Basic clinical data (symptoms and signs, arterial blood gases, chest X-ray and EKG) were extracted and given to five clinicians, who were asked to estimate the probability of PE. We determined the inter-clinician agreement and compared their estimates with the final diagnoses.

RESULTS

Among patients with a final diagnosis of PE, clinical estimations of PE probability were: high in 63%, intermediate in 21%, and low in 16%. The accuracy of estimates varied between 67 and 80%. Actual PE prevalence was 81% among cases estimated as having high probability and 42% in those considered as low probability. The global inter-clinician agreement rates ranged from 56 to 72%, whereas the average kappa coefficient was 0.44.

CONCLUSION

Basic clinical data seem to be more useful to predict PE than to exclude it. The accuracy and agreement between estimates from different clinicians are only moderate.

Serum proteolytic activities and antiproteases in human colorectal carcinoma

Some proteolytic enzymes, trypsin, cathepsin B, cathepsin D, collagenase, elastase and their inhibitors, API and AMG, in serum of patients with colorectal carcinoma have been evaluated. Twenty patients belonged to stage B of colorectal carcinoma, twenty two patients to stage D (Astler and Coller classification) and a control group of thirty healthy volunteers were evaluated. Except in cathepsin D, patients exhibit higher enzymatic activities than healthy subjects, and both groups have all the proteolytic activities assayed in serum. Patients with disseminated disease have increased cathepsin B and collagenase levels, with a decrease of trypsin activity, showing an increment in API and AMG in sera. However, only the API values were significantly higher in patients with metastases. The coexistence of proteolytic activities in human sera together with their inhibitors is considered as well as the origin of these, tumoral and/or reactive, increments. Cathepsin B levels are raised in colorectal neoplasms and contribute to the destruction of the extracellular matrix and the proliferation of tumoral cells. There is evidence that a relation between collagenase like activity and tumor invasiveness exists. Cathepsin B and collagenase increases agree with the tumoral mass. On the other hand, trypsin decrease in metastatic carcinoma is probably related to the increment of their inhibitors, API and AMG, acute phase reactant proteins.

Thixotropy of highly viscous sodium (carboxymethyl)cellulose hydrogels

A general method to quantify the thixotropic behavior of systems with very low thixotropy is proposed. The areas enclosed by the rheograms tau = f(gamma) must be fitted to functions with well-determined boundary conditions. From these equations the corresponding thixotropic areas are obtained, together with the theoretical area enclosed by the rheogram corresponding to the maximum rheodestruction. The proposed method is applied to high viscosity sodium (carboxymethyl)cellulose gels.

[Nutritional support in bone marrow transplantation]

Bone marrow transplant (BMT) implies the treatment with substances which may compromise the nutritional condition, thus increasing the morbido-mortality of these patients. The objective of this study is to evaluate the efficacy of the nutritional support (NS) protocol for patients subjected to a BMT in our center.

PATIENTS AND METHODS

55 patients were included (24 men and 31 women), who were subjected to BMT during 1994, with prior chemotherapy depending on the underlying disease. The nutritional condition (NC) was evaluated upon initiation and at the end of the NS, using anthropometric, biochemical, and immunological parameters. The NS was given by total parenteral nutrition (TPN), adapted to the needs, as of the second post-transplant day, until such time that oral nutrition was sufficient to supply the nutritional needs of the patients; oral ingestion was permitted at all times, according to the possibilities of the patient. For the statistical analysis, we used the Student's t test, Pearson's Chi squared test, and Spearman's test, with differences being considered significant for values < 0.05.

RESULTS

The average duration of the TPN was 16 +/- 6 days, with a significantly longer time (p < 0.05) in patients with leukemia. The NC assessment was no different at the beginning and at the end of the NS, although all groups show a drop in the albumin levels at the end with respect to those at the beginning, with this being statistically significant in patients with leukemia (p < 0.05), and with solid tumors (p < 0.01), 14.5% of the patients maintained an acceptable oral ingestion (with 75% having lymphomas), and 34.5% did not show any associated oral ingestion. Te better albumin maintenance was correlated with acceptable oral ingestion (p < 0.05).

CONCLUSIONS

Nutritional support of patients subjected to a BMT is effective for maintaining their NC levels. The longest duration of the TPN, the lowest frequency of associated oral ingestion, and the greatest decrease of the serum albumin, levels are seen in those cases which had the most aggressive chemotherapy prior to the BMT, which requires adaptation of the NS in function of the underlying disease. The association of oral ingestion may be beneficial due to its effect on the gastrointestinal tract.

Shear stress synergism index and relative thixotropic area

Shear stress synergism index and relative thixotropic area are introduced as quantifiers of viscous synergism and comparative thixotropy. The utility of these terms is demonstrated by their application to microcrystalline cellulose-sodium carboxymethyl cellulose (MCC-NaCMC) hydrogel, a starch of different botanical origins hydrogels and their combinations.

[Testicular seminoma manifested by carcinomatous neuropathy: an unusual presentation. Review of the literature]

Contribution of one patient with tetraparesic picture originated by a major sensory-motor neuropathy, due to paraneoplastic syndrome produced by a testicular seminoma. The patient underwent inguinal orchiectomy and radiotherapy, with favourable evolution of his neurological symptomatology. Review of the literature and confirmation of the extraordinary rarity of such clinical picture.

[Programs of diabetological education: a basic tool in the treatment of diabetes mellitus]

To assess whether the programs of diabetologic education (PDE) are effective to improve metabolic control in diabetes mellitus, depending on their inclusion in an overall therapeutic program and on the setting where they are imparted (hospital versus primary care center, PCC), we evaluated the changes in the HbA1 values in 230 insulin-treated diabetic patients, after receiving a PDE in a PCC (group A; n = 88) or as hospital inpatients (group B; n = 72) or outpatients (group C; n = 50). The remaining 20 patients (group D) received the same PDE, but their treatment did not depend on our Unit. The initial mean HbA1 levels were significantly reduced 3, 6 and 9 months after the PDE in group A patients (10.6% vs 9.6%, p less than 0.05; vs 9.4%, p less than 0.02; vs 9.1%, p less than 0.01), in group B patients (10.0% vs 9.5%, p less than 0.05; vs 9.1%, p less than 0.05; vs 9.0%, p less than 0.05) and group C patients (10.1% vs 9.5%, p less than 0.05; vs 9.1%, p less than 0.02; vs 8.9, p less than 0.01); however, they did not significantly change in group D patients (10.3% vs 10.7%, vs 10.3%, and vs 10.0%). Mean HbA1 in months 3, 6 and 9 were not different between groups A, B and C, but they were lower (p less than 0.05) than in group D. Our results confirm that PDE and treatment are effective to improve metabolic control in diabetic patients, whereas diabetological education alone is not useful. The place where PDE is given is not determinant for its effectiveness.

[Brucellosis at a tertiary hospital. Retrospective epidemiologic study of 166 cases]

The epidemiologic polls concerning 166 cases of brucellosis are retrospectively analyzed; the cases are registered by the Preventive Medicine Service of Miguel Servet Hospital for five years (1980-1985). Most of our cases are of recent evolution, although 55% began to give symptoms more of 2 weeks ago and 30% more of 1 month ago. A clear annual increase of the number of cases, fundamentally of the male sex and patients coming from the rural areas, is observed. The percentage of cases in men (73.5%) is almost three times as those in women (26.5%), and the most numerous groups are the 20-29 interval age group and olders above 60. There is a small percentage of people with a professional risk factor (30.1%), which rise, slightly, for the ones who told of contact with cattle (39.2%) and rose up to 53.6% for the ones who consumed non controlled dairy products. However, in 23% of men and 40.9% of women the existence of some risk factors was unknown.

[Dental fluorosis in San Luis Potosi and its solution alternatives (pilot study)]

A study exposing the situation affecting the population of San Luis Potosí in central México, caused by dental fluorosis. Findings point to the need of implementing devices capable of regulating the concentrations of Fluorine ion (generating the efficient prevention of dental cavity incidence), to maintain them at optimal levels and without deletereal effects.

Hepatic fibrin-ring granulomas in visceral leishmaniasis

Hepatic fibrin-ring granulomas and leishmania parasites were found in the liver biopsy specimens of 3 patients with prolonged fever and hepatosplenomegaly. It was recognition of the leishmanias in the liver biopsy specimen that prompted the diagnosis in all cases. There was no evidence of Q fever, Hodgkin's disease, cytomegalovirus hepatitis, or allopurinol treatment, which are the recognized causes of hepatic fibrin-ring granulomas. This report extends the range of etiologies of hepatic fibrin-ring granulomas. As a result, leishmaniasis should always be a consideration to the pathologist and the clinician in the differential diagnosis of fibrin-ring granulomas.

Choroid plexus blood flow in the sheep

Choroid plexus blood flow was measured in 29 adult female sheep using the radioactive microsphere technique. Basal blood flow, response to change in arterial carbon dioxide tension, and response to change in mean arterial blood pressure were determined. The results were compared to cerebral cortical blood flow values in the same sheep. Mean choroid plexus blood flow was 601 ml/100 g/min under basal conditions. Choroid plexus blood flow fell 31% with hypocarbia, a reduction comparable to that seen in cortex. With hypercarbia choroid plexus blood flow rose only 27% whereas cortical blood flow increased by 199%. Unlike cortical blood flow, choroid plexus blood flow fell significantly with pharmacogenic hypertension. The latter finding may reflect the absence of a blood-brain barrier in choroid plexus.

Cerebral blood flow and metabolism during hypoglycemia in newborn dogs

Cerebral blood flow (CBF) and cerebral metabolic rates (CMR) were studied in newborn dogs during insulin-induced hypoglycemia. Pups were anesthetized, paralyzed, and artificially ventilated with a mixture of 70% nitrous oxide and 30% oxygen to maintain normoxia and normocarbia. Experimental animals were given regular insulin (0.3 units/gm IV); controls received normal saline. CBF was determined using a modification of the Kety-Schmidt technical employing 133Xe as indicator. Arteriovenous differences for oxygen, glucose, lactate, and beta-hydroxybutyrate (beta-OHB) were also measured, and CMRO2 and CMRsubstrates calculated. Two groups of hypoglycemic dogs were identified; those in which blood glucose levels were greater than 0.5 mM (group 1), and those in which they were less than 0.5 mM (group 2). CBF did not change significantly from control values of 23 +/- 10 ml/min/100 g (mean +/- S.D.) at both levels of hypoglycemia. Similarly, hypoglycemia did not alter CMRO2 significantly from its initial level of 1.05 +/- 0.37 ml O2/min/100 g. Glucose consumption in brain during normoglycemia accounted for 95% of cerebral energy supply with minimal contributions from lactate (4%) and beta-OHB (0.5%). During hypoglycemia, CMRglucose declined by 29 and 52% in groups 1 and 2, respectively, while CMRlactate increased to the extent that this metabolite became the dominant fuel for oxidative metabolism in brain. The cerebral utilization of beta-OHB was unaltered by hypoglycemia. The findings indicate that insulin-induced hypoglycemia in the newborn dog is associated with an increase in cerebral lactate utilization, supplementing glucose as the primary energy fuel and thereby preserving a normal CMRO2. These metabolic responses may contribute to the tolerance of the immature nervous system to the known deleterious effects of hypoglycemia.

Cerebral blood flow and oxygen consumption in the newborn dog

Cerebral blood flow (CBF), CBF responses to changes in arterial CO2 tension, and cerebral metabolic rate for oxygen (CMRO2) were measured in newborn dogs, by means of a modification of the Kety and Schmidt technique employing 133Xe. Mongrel dogs of 1-7 days of age were paralyzed and passively ventilated with 70% N2O and 30% O2. CBF was derived by analysis of paired serial 20-microliter samples of arterial and of cerebral venous blood from the superior sagittal sinus. At an arterial PCO2 of 36.9 +/- 3.7 Torr and a mean arterial blood pressure of 62 +/- 10 Torr, CBF was 23 +/- 8 ml/min per 100 g. The arteriovenous oxygen content difference averaged 5.6 vol%, and CMRO2 was 1.13 +/- 0.30 ml O2/min per 100 g. CBF increased or decreased by 0.58 ml/min/100 g per Torr change in PCO2. Our results suggest that in the newborn, basal CBF and CBF responses to CO2 are considerably lower than in the adult and parallel the lower metabolic needs of the newborn brain.

Cerebral blood flow autoregulation in the rat

Cerebral blood flow autoregulation (CBFA) to changes in perfusion pressure has not been previously reported in the rat. A modification of the Kety and Schmidt technique employing 133Xenon was used to measure cerebral blood flow (CBF) in paralyzed adult Sprague Dawley rats passively ventilated with 70% nitrous oxide and 30% oxygen. At a mean arterial blood pressure (MABP) of 121 +/- 19 mm Hg, and a mean arterial PCO2 of 36.2 +/- 2.9 mm Hg, mean CBF was 103 +/- 22 ml/min/100 gm of brain. CBF responses to hypercarbia were 4.9 ml/min/100 gm per mm Hg change in arterial PCO2. CBF was measured during steady state levels of hypo- and hypertension induced by phlebotomy, or by intravenous metaraminol, over the MABP range of 48-205 mm Hg. From a MABP of 80 to 160 mm Hg. CBF remained nearly constant, indicating the presence of CBFA. However, when MABP exceeded 160 mm Hg, CBF became pressure dependent, indicating a "breakthrough" of autoregulation in acute severe hypertension.