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Biomedical subjects

M Díaz

Publications and source records attributed to M Díaz.

At least 37 records · Page 2Linked to original sources
PubMed2004

Prospective safety study of immunotherapy administered in a cluster schedule.

Cluster immunotherapy is becoming an alternative to conventional IT due to its shorter schedule, but the safety of such schedule is still controversial. At present, only few studies assess the risk of immunotherapy in a prospective manner, in well-controlled patients, using the same extract and intending to evaluate a single schedule. The aim of the present study is to evaluate the safety of a cluster immunotherapy administration regimen. A total of 91 outpatients (41 male and 50 female), with a mean age of 25 years old (range: 16-50) were included. Sixty-one patients were diagnosed mild to moderate asthma and 30 rhinoconjunctivitis. Forty-six of the enrolled patients were sensitised to pollen (Lolium perenne and/or Olea europea), 38 to Dermatophagoides pteronyssinus and 7 to Alternaria alternata. Patients received specific immunotherapy following a five-week cluster schedule. It was considered as a preseasonal treatment, that is, it was accomplished before olive and grass initial pollinating months in this area (March--April). A total 1029 injections were administered during the induction phase. Adverse reactions were assessed and classified according to the EAACI criteria. The average number of visits to maximum dose was 6 (range 2-10), and 70 patients (77%) reached the maximum between 5-7 visits. In each of the visits an average of 2 (range 1-3) injections were administered. Eighty-one of the 91 initially enrolled patients (89%) completed the cluster schedule. The total number of reactions were 47 (24 local and 23 systemic). No fatal reactions were observed. Since the total number of administered injections was 1029, the relative frequency of adverse reactions was 4.6% (2.3% local and 2.2% systemic). The percentage of patients affected by systemic reaction was 18% and by local reaction 14%. No relationship can be shown between adverse reactions and gender or disease. However, a clear relationship with the composition of immunotherapy has been shown, with a lower risk of adverse reactions associated with the extract of D. pteronyssinus. The shorter period required to achieve the maintenance dose, with a similar frequency of adverse events, leads to the conclusion that the proposed administration regimen can be an alternative to conventional schedule to increase patient compliance.

Adolescent↗
PubMed2003

Ionic shell and subshell structures in aluminum and gold nanocontacts.

Conductance histograms of aluminum and gold nanocontact rupture are studied experimentally and simulated using embedded atom potentials to assess the interplay between electronic and structural properties at room temperature. Our results reveal a crossover from quantized conductance structures to crystalline faceting or geometric shell/subshell structures at 300 K. The absence of electronic shell structure in gold and aluminum is in stark contrast with the behavior of alkaline metal nanowires which emulate their cluster counterparts. Semiclassical arguments suggest why rapid dominance of ionic structures takes place, and possible nanowire architectures are proposed in consistency with both the experimental and simulated nanocontact data.

Journal Article↗
PubMed2003

Temperature-activity relationship for the intestinal Na+-K+-ATPase of Sparus aurata. A role for the phospholipid microenvironment?

The temperature dependence for Na(+)-K(+)-ATPase has been examined in the proximal-distal axis of the intestine of gilthead seabream (Sparus aurata), i.e. pyloric caeca (PC), anterior intestine (AI) and posterior intestine (PI). Data derived from the Arrhenius plots showed differences in terms of temperature discontinuity points ( Td) (13.29 degrees C, 16.39 degrees C and 17.48 degrees C for PC, AI and PI, respectively) and activation energy ratios (Ea(2)/Ea(1)) obtained at both sides of Td (2.38, 1.98 and 1.78, for PC, AI and PI, respectively). The analyses of polar lipids showed differences in the levels of certain fatty acids among intestinal regions. The content of each fatty acid and different fatty acid ratios were correlated with the corresponding Td and Ea(2)/Ea(1) values. Regression analyses revealed the existence of strong negative correlations between docosahexaenoic acid (22:6n-3, DHA) or the DHA/monoenes ratio and Td. No obvious relationships were observed for other polyunsaturated fatty acids (PUFA) nor saturated fatty acids. The results obtained in the present study indicate that the heterogeneous values of Td displayed by the Na(+)-K(+)-ATPase along the intestinal tract could be related to a modulatory role of certain fatty acid within the lipid microenvironment of the enzyme.

Animals↗
PubMed2003

[Arterial trauma in the first year of life].

Traumatic vascular lesions in neonates are usually due to preoperative iatrogeny. In the last ten years, we attended 11 patients aged less than one year with arterial lesions due to deliberate puncture. All required endovascular, surgical or combined treatment. The intra- and postoperative follow-up of severe congenital malformations necessitates appropriate arterial access. This should be achieved following strict protocols, with a limited number of punctures carried out by experienced staff and only in large arteries. When a vascular lesion occurs, first an endovascular and then a surgical approach is required in the shortest time period possible. In conclusion, care of arterial routes of access and their maintenance is the best preventive therapy. Appropriate and early treatment in fistulas, pseudoaneurysms and thrombosis must be provided to prevent serious complications, especially in underweight patients.

Angiography↗
PubMed2003

Maintenance treatment with depot opioid antagonists in subcutaneous implants: an alternative in the treatment of opioid dependence.

A report is presented of treatment of 156 patients (male 98%) with opioid dependence (ICD-10 criteria) using a maintenance programme with depot opioid antagonists (naltrexone) as subcutaneous implants, started after an outpatient rapid antagonization regimen. The retention index in the treatment was from 80% in the sixth month, and 65% after one year. The patients were followed-up for 1 year after discharge. For 6 months after discharge 55.4% were still returning for follow-up visits and 20.8% after 1 year, all of them remaining abstinent to opioids. It is concluded that the programme is safe for the patients and shows a better retention index than programmes using oral antagonists, with an improved compliance (negative urine analysis) compared to the latter.

Adult↗
PubMed2003

[Extensive aganglionosis. Treatment and long term results].

INTRODUCTION: Extensive aganglionosis (EA) that affects the total colon (including or not part of the small intestine), shows more diagnostic problems and it is associated to higher morbidity and mortality rates than the classic cases of Hirschsprung disease (ED). This study takes into account last years cases and their results in the medium and long term. MATERIAL AND METHODS: Between 1983 and 2000, 232 patients suffering ED have been treated. 15 out of those 232 patients showed EA. We took into consideration the diagnosis, surgical procedures, enterocolitis before and after the treatment, the surgical technique and the complications. We analyze the nutritional state and the long term result according to clinical bowel function scoring system continency Scale, considering the surgical possibilities depending on each case. RESULTS: Two patients died due to septics complications, one of them during the neonatal period and the other one at the age of 3. Two other cases became possible candidates to an intestinal transplantation due to the extension of their disease. Five out of the 11 left patients had more than 30 cm of small intestine involved, and another five had involved less than 30 cm from ileocecal valve. The last case showed a total colonic aganglionosis with associated intestinal neuronal displasia. One case was associated with S. Ondine and another one with a 21 triosomia. Two of the patients were brothers and another patient has got a brother suffering from rectosigmoid HD. The surgical techniques used with 13 were: 8 cases using Lester Martin modification (one of them needed redo procedure because of anastomosis leak and perineal fistula), 4 Swenson procedure and one patient was treated by Ziegler's miectomy with prolongated miotomy. Nine of the patients mentioned before, lead a quite life (five L, Martin, 4 Swenson); 2 patients suffering frequent fecal retention crisis. 5 out of the 11 reviewed cases, show a weight and height p > or = 50, 2 below p50, 2 below p25, and 2 under p3. CONCLUSION: EA represents a small percentage of Hirschsprung disease. Although Martin modification is the most widely employed technique in cases of distal ileal involvement, Swenson procedure has provided good results in the long term follow-up with few complications. Intestinal transplantation may be the only choice for long term survival in patients with near total intestinal aganglionosis. Continence improves in the follow-up but few times is normal. Nutritional state should be-controlled by a specialized team.

Child, Preschool↗
PubMed2003

[Giant congenital nevus: past, present and future].

INTRODUCTION: The suitable cutaneous covering for big defects secondary to the removal of giant pigmented lesions has not been obtained yet. Nevus that affect a corporal surface bigger than 75%, have no curative treatment and in the cases of smaller nevus therapeutical possibilities are complex, take too much time and provide unfavourable aesthetic results. MATERIAL AND METHODS: Nineteen patients suffering giant congenital nevus (GCN) have been treated in the last eight years. The GCN affected back (8), scalp (3), face and neck (3), extremities (2), thorax and abdomen (2) and buttocks (1). RESULTS: There has been no melanoma case and all the cases showed a congenital melanocitic nevus as histological result, with plexiforme underlying plexiform neurofibroma in two of them. The treatment was: removal using expansors (6), removal and skin graft (5), multiple sequential removals (7), and removals using a covering of cultured keratinocites (1). CONCLUSION: To sum up, it is essential to choose the technique depending on the individual, taking into account the location, measurement, age and social conditions. In addition to that, the treatment shouldd be the earliest, the most effective, the fastest and the most secure. Moreover, it is very important to know every surgical technique well.

Adolescent↗
PubMed2003

[Severe complications in the treatment of vascular anomalies].

BACKGROUND: Success in the treatment of vascular anomalies during infancy depends on an accurate early diagnosis and a correct therapeutic management. Current available resources can be divided into pharmacologic, endovascular, surgical, and laser. Results are variable, and complications should always be kept in mind. METHODS: We reviewed all patients with vascular anomalies who suffered from major complications directly due to the treatment during the past five years. RESULTS: 1. A patient with an upper lip hemangioma following treatment with interferon after no response to steroids. A long-term severe neutropoenia forced to an early surgical excision of the lesion. 2. A patient suffering from an orbitary hemangioma with severe exoftalmus was treated with interferon because of a steroid-resistance. A spastic diplegia due to interferon reverted after treatment was discontinued. 3. In a patient with a Blue-Rubber Bleb Nevus syndrome, extended percutaneous sclerosis was performed. She developed skin necrosis of the left leg and a permanent sciatic nerve paralysis. 4. In a patient with an arteriovenous malformation on the right leg and gluteous, a femoral artery endoprosthesis was placed because of a massive bleeding. She underwent a total excision of the malformation and developed a recurrent ischemia related to a femoral thrombosis. Finally a foot amputation was needed. 5. A patient with a Kaposi-like hemangio-endothelioma who was following a high-dose prolonged steroid therapy died because of a meningoencephalitis related to a severe immunosuppression. CONCLUSIONS: Treatment of vascular anomalies during childhood need an early accurate diagnosis. If a right therapeutic sequence is not performed, useful drugs can turn into inefficient or dangerous. Most treatment complications in these patients can be avoided.

Blood Vessels↗
PubMed2002

Effectiveness factor in biological external convection: study in high viscosity systems.

A study regarding the influence of mixing on the efficiency of alginate and xanthan synthesis was carried out. The effectiveness of these two systems in terms of a dimensionless reaction convection number (N(RC)), which is a function of the power input per unit volume, was analysed and compared with low viscosity systems. The results revealed that a decrease in the power input caused a reduction in the growth rate as well as in production rate. It was observed that the effectiveness factor (eta) both for alginate production and xanthan synthesis resulted weakly dependent on the biomass content. A good correlation between effectiveness and N(RC) was obtained for the two tested models. N(RC) number could be appropriately employed in correlating the effectiveness factor for processes with viscosities from 0.001 to more than 1 kg m(-1) s(-1). Due to the parallelism with the conventional internal diffusion approach (Thiele modulus), the advantages for applying N(RC), in particular to correlate the efficiency in systems limited both for external convection and internal diffusional resistance, are shown.

Alginates↗
PubMed2002

Digestive proteases during development of larvae of red palm weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Curculionidae).

The evolution of digestive proteases during larval development of Rhynchophorus ferrugineus (Olivier, 1790) has been studied. A progressive increase of protease activity has been found. The optimum pH for proteolytic activity against azocasein was determined. Caseinograms revealed an active complex of alkaline proteases from the early stages of the development. From the apparent molecular masses, three groups of proteases have been found - high molecular-mass proteases, medium molecular-mass proteases, and low molecular-mass proteases. Studies using specific protease inhibitors showed the major presence of serine proteases in gut extracts. The results obtained from larvae reared on different substrates have made possible a comparative assessment of the influence of diet on the development of the digestive enzymatic system. Larvae fed on an artificial diet showed a complete pattern of digestive proteases. Data suggest that this diet seems to be suitable for future research with this insect pest.

Animals↗
PubMed2002

A light and electron microscopic study of oedematous human cerebral cortex in two patients with post-traumatic seizures.

PRIMARY OBJECTIVE: Brain cortical biopsies of two patients with clinical diagnosis of complicated brain trauma who had seizures, were studied by means of light and electron microscopes in order to correlate structural alterations with seizure activity. METHODS AND PROCEDURES: Biopsy samples of left frontal cortex and right parietal cortex were processed by current techniques for light and transmission electron microscopy. RESULTS: The tissue showed severe vasogenic oedema with perivascular and intraparenchymatous haemorrhages. At the capillary wall, increased vesicular and vacuolar transendothelial transport, open endothelial junctions, thickened basement membrane and swollen perivascular astrocytic end-feet were observed. Some pyramidal and non-pyramidal nerve cells appeared dense and shrunken and others exhibited marked intraneuronal enlargement of membrane compartment. The myelinated axons displayed signs of degeneration and a process of axonal sprouting. Numerous swollen asymmetrical axo-dendritic synaptic contacts were observed in the neuropil, which exhibited mostly closely aggregated spheroidal synaptic vesicles toward the presynaptic membrane and numerous exocytotic vesicles sites. The perisynaptic astrocytic ensheathment appeared retracted or absent, whereas the extracellular space appeared notably dilated. Synaptic disassembly was also observed. CONCLUSION: The findings demonstrate, in two patients with post-traumatic seizure activity, brain barrier dysfunction, vasogenic oedema, anoxic-ischaemic neurons, axonal sprouting, numerous altered excitatory synapses and synaptic disassembly. Some considerations on clinical and research applications are discussed.

Adolescent↗
PubMed2002

[High flow vascular malformations in children].

Unlike hemangiomas and low-flow vascular malformations which are very common in children, arterial anomalies have small incidence. Differential diagnosis is difficult, and needs a physician familiarized with vascular anomalies. Appropriate treatment must be planned by multidisciplinary team considering the patient's age, and anatomical location. Twenty-eight children with high flow vascular malformations have been treated since 1990 at La Paz Children's Hospital Vascular Anomalies Program. We excluded of the study group patients with central nervous system lesions. 85% of the patients had malformation in stage I or II (according the ISSVA accepted Schöbinger stating) and most of them were erroneously diagnosed as hemangioms with a variety of inappropriate treatments previously performed. Doppler Ultrasound and Magnetic Resonance confirmed malformation flow and extension. Angiography and selective embolization was only considered as therapeutic approach in candidates to surgical resection. 16 patients underwent complete resection of the malformation including one foot and two fingers amputation and five more incomplete resection of the ulcerate area. In conclusion, we did not find age at onset, sex and symptoms relationship. Laser, radiotherapy, surgical ligation or partial resection must be considered inappropriate therapies which may stimulate AVM exacerbation. Only radical surgical procedure after selective endovascular embolization will be successful but then reconstructive surgery should be performed to achieve good aesthetic and functional results.

Adolescent↗
PubMed2002

[Integra Artificial dermis in pediatric reconstructive surgery].

UNLABELLED: The recent release of artificial dermis for general use, has open wide a new field in pediatric reconstructive surgery. The aim of this paper is to analyze the results of Integra artificial dermis in our Plastic Surgery Department. MATERIALS AND METHODS: The records of the patients treated with Integra between february 1999 and january 2001 were analyzed, focusing on the indications, the complications and the final results. RESULTS: Fourteen Integra implantation procedures in 11 patients aged 16 months to 12 years (mean +/- SD: 80.9 +/- 48.5 months) were performed. Indications were: acute burns in 5 cases, burns sequelae in 5, and partial extirpation of a congenital giant nevus in the last one. Integra was used to replace between 2 and 30% of total body surface area. The percentage of "take" of skin grafts was 85%. The most frequent early complication was the development of infection under the Integra; it occurred in 2 cases and artificial dermis had to be partially removed. Hypertrophic scars developed in 2 patients; both had refused pressure garments. Cosmetic results in the remaining 9 patients are considered excellent. CONCLUSIONS: The use of artificial dermis has settled as a new procedure in plastic pediatric surgery. In spite of possible complications, the easy manipulation and the good results make Integra a perfect skin substitute in several cutaneous disorders.

Biocompatible Materials↗
PubMed2001

Expression of the genes coding for the xylanase Xys1 and the cellulase Cel1 from the straw-decomposing Streptomyces halstedii JM8 cloned into the amino-acid producer Brevibacterium lactofermentum ATCC13869.

The xylanase ( xysA) and the cellulase ( celA1) genes from Streptomyces halstedii JM8 were cloned into Escherichia coli/ Brevibacterium lactofermentum shuttle vectors and successfully expressed in both hosts when placed downstream from the kanamycin resistance promoter (Pkan) from Tn 5 but not when under the control of their own promoters. Xylanase was secreted into the culture media of B. lactofermentum by removal of the same leader peptide as is removed in S. halstedii. The main difference between the production of xylanase by Streptomyces and corynebacteria was the low level of processing of the mature extracellular xylanase by B. lactofermentum, probably due to the lack of protease activity in this microorganism.

Amino Acid Sequence↗