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Biomedical subjects

M A Martinez

Publications and source records attributed to M A Martinez.

At least 19 recordsLinked to original sources
PubMed2006

Influence of the tunnel angle in ACL reconstructions on the biomechanics of the knee joint.

BACKGROUND: A high tension in anterior cruciate ligament grafts affects both graft and knee functional performance. Clinical observations suggest that impingement of the graft against the posterior cruciate ligament might cause high graft tensions. Also, meniscal injury has been well documented in association with damage in the anterior cruciate ligament. METHODS: In this paper, we present the results obtained in a three-dimensional finite element model of the human knee, corresponding to different aspects of anterior cruciate ligament reconstruction with bone-patellar tendon-bone grafts. This model was used to investigate the effect of the angle in the coronal plane of femoral and tibial tunnels. Firstly, graft tension was computed in a knee moved from 0 degrees to 60 degrees of flexion and the results were compared with experimental ones obtained by other authors. Secondly, the resulting kinematics under an anterior load of 134 N was compared to that of the intact knee. FINDINGS: The obtained results showed that the closest anterior tibial translation to that of the intact knee was obtained with femoral and tibial tunnels with angles of 60 degrees. In this same case, a lower graft tension was also obtained. The results demonstrated noticeable increases in the meniscal stresses after anterior cruciate ligament reconstruction. INTERPRETATION: Our results showed that impingement only depends on the femoral tunnel angle. On the contrary, laxity principally depends on the tibial tunnel angle. The angle of the femoral tunnel affects the graft tension while the tibial tunnel affects laxity, meniscal stresses and strains.

Anterior Cruciate Ligament↗
PubMed2006

[The vacuum chest wall lifter in the treatment of pectus excavatum].

Since 2002, the Eckart Klobe vacuum has been used in our Service as an innovate and non-invasive procedure in patients with pectus excavatum. This vacuum method contributes not only to hold promise as a valuable adjunct in minimally invasive surgery, but also as an effective method to lift and fix the funnel for repairing pectus excavatum in some patients. Our experience is limited to the use of this device in 10 patients, during the Nuss technique. This procedure has been useful for safer passage of the introducer, and as a definitive treatment in a 10 years old girl with pectus excavatum and a Haller index of 5.1 with successful result after one year of treatment. The aim of this study is to report the safety and efficacy of this procedure in appropriate patients. Long-term results will be necessary to confirm this method as an alternative to more invasive techniques.

Child↗
PubMed2003

Removal of Cu and Zn from swine raising wastewater using organic filters.

Rice husks, coffee bean skins, sugar cane bagasse, maize cobs, saw dust and fine charcoal dust were evaluated as filters for the removal of heavy metals (Cu and Zn) from the waste water of swine raising installations. The specific mass, pH and the sum of bases and removable acids were determined to characterize each of the filter materials. Each filtering material was placed in a 100 mm diameter, 600 mm long, PVC column to a height of 500 mm under 12,500 N m(-2) of compression. Chemical and physical analyses were determined on effluent samples collected for each 1.5 l up to a total of 15 l. The organic materials reduced the concentration of sediment solids (> 90%), total solids (up to 33%) and Cu (up to 43.6%) of the inffluent but had little or no effect on Zn concentration.

Animals↗
PubMed2002

Severe lung involvement in systemic scleromyxoedema: a highly unusual finding.

Scleromyxoedema is a rare systemic disorder characterized by a lichenoid papular rash. Although scleromyxoedema can involve any organ, very few cases of pulmonary involvement have been reported. Moreover, there are no reports in the literature on treatment of this condition, especially with lung transplantation. The authors report a case of scleromyxoedema in a young man with neurological, skin and respiratory involvement, the latter being mainly characterized by pulmonary emphysema. Due to the serious respiratory compromise, and to the stability of the systemic lesions, a bilateral lung transplantation was performed with successful results at 4.5 yrs. In conclusion, lung transplantation may be required in patients with severe respiratory failure caused by scleromyxoedema.

Adult↗
PubMed2001

Mobility of heavy metals as related to soil chemical and mineralogical characteristics of Brazilian soils.

In order to better understand the relationship between soil characteristics and mobility of some heavy metals, correlation studies were conducted in samples of unlimed and limed A, B and C horizons of three Brazilian soils, representative of the majority of the tropical soils. A number of chemical and mineralogical characteristics of one Oxisol and two Ultisols were related to the retardation factors (Rf) for zinc (Zn), cadmium (Cd), copper (Cu) and lead (Pb). The retardation factors, obtained in leaching column experiments, were used as an estimate of solute movement in the profile. Soil types and soil horizons were found to influence metal retardation factors which, in turn, correlated better with the chemical than the mineralogical soil characteristics. For the unlimed soil samples, the soil characteristics that significantly correlated with Zn-Rf and Cd-Rf were the sum of exchangeable bases (SB), and soil exchangeable (Ca-KCl) and non-exchangeable (Ca-HCl) calcium contents. These results showed the strong influence of the cation exchange phenomenon on the retention and mobility of these two metals. For Cu and Pb, not only SB, cation exchange capacity (CEC) and Ca-KCl and Ca-HCl but also the organic matter correlated well with the Rf, showing that complex or chelate formation may play an important role in the movement of these elements. The important soil chemical characteristics related to the retardation factors in the limed soil samples were SB for Cd, and Ca-HCl for Cu and Pb, suggesting that precipitation may also influence the mobility and retention of the latter two heavy metals in these soil samples. Soil pH influenced the heavy metals adsorption and movement as shown by the significant correlation with the retardation factors when the combined data for the unlimed and limed soil samples was considered.

Adsorption↗
PubMed2001

Only early intervention with gamma-aminobutyric acid cell therapy is able to reverse neuropathic pain after partial nerve injury.

Pharmacological treatment for neuropathic pain, although often effective for brief periods, can result in intractable persistent pain with certain patients. Cell therapy for neuropathic pain is a newly developing technology useful for an examination of enhanced normal sensory function after nerve injury with the placement of cells near the spinal cord, and grafts of immortalized cells bioengineered to chronically supply the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) have been used to reverse the chronic pain behaviors. However, it is not known whether there is a therapeutic window for the use of intervention with cell therapy after partial nerve injury. To investigate whether neuropathic pain is sensitive to the timing of placement of cell grafts, neuronal cells bioengineered to synthesize GABA were transplanted in the lumbar subarachnoid space one to four weeks after unilateral chronic constriction injury (CCI) of the sciatic nerve and sensory behaviors were evaluated before and after CCI and transplants. Both thermal hyperalgesia and tactile allodynia were reversed when transplants were placed either one or two weeks after partial nerve injury, compared to maintenance of these behaviors with the injury alone. However, if GABA cells were placed any later than 2 weeks after nerve injury, such intervention was ineffective to reverse the thermal and tactile hypersensitivities induced by the injury. This suggests that altered spinal GABA levels may contribute to the early development of chronic neuropathic pain and that early intervention with cellular therapy to restore GABA may prevent the development of that pain.

Animals↗
PubMed2001

Accidental dichloromethane fatality: a case report.

A case of accidental dichloromethane poisoning by inhalation is presented. It is of interest that carboxyhemoglobin levels were within the normal range, suggesting that the narcosis and respiratory depression were due to the direct effect of DCM on the central nervous system. The accidental death was attributed to improper ventilation of vapors in the working area.

Adult↗
PubMed2000

Splenic littoral cell angioma in an infant.

A 1-year-old girl presented with fever, asthenia, and splenomegaly with hypersplenism. Abdominal ultrasound scan and magnetic resonance imaging showed multiple nodular cystic masses in an enlarged spleen. The histological examination of the resected spleen showed a novel type of vascular tumor called littoral cell angioma. The histopathologic and immunohistochemical features of this rare lesion are described. Distinction from other splenic vascular tumors is stressed because the clinical behavior of this new entity seems to be benign.

Diagnosis, Differential↗
PubMed2000

Cytotoxicity in pig hepatocytes induced by 8-quinolinol, chloramine-T and natamycin.

The potential cytotoxic effects of the compounds 8-quinolinol, chloramine-T and natamycin have been studied in isolated pig hepatocytes. The relative cytotoxicity of these compounds was evaluated on the basis of the leakage of cytosolic lactate dehydrogenase (LDH), 3-(4,5 dimethyl)thiazol-2-yl,-2,5-diphenyl tetrazolium bromide (MTT) reduction by mitochondrial dehydrogenases, uptake of neutral red (NR) by cytosolic lysosomes, glutathion (GSH) depletion and oxidized glutathion (GSSG) efflux after 24 h exposure. Evaluation of the 20%, 50% and 80% reduced absorbance data obtained from the parameters NR20, NR50, and NR80, and MTT20, MTT50 and MTT80 enabled us to rank these compounds in decreasing order of cytotoxicity: 8-quinolinol > natamycin > chloramine-T. Also for the parameters LDH and GSH, chloramine-T appears to be less cytotoxic than natamycin and 8-quinolinol. Our study demonstrated that pig hepatocytes may be a useful model for examining cytotoxic events of drugs to be used in pigs, therefore avoiding possible extrapolation problems due to species differences.

Animals↗
PubMed1999

A single intrathecal injection of GABA permanently reverses neuropathic pain after nerve injury.

To investigate whether neuropathic pain is sensitive to spinal GABA levels, GABA was injected intrathecally after nerve injury and sensory behaviors were evaluated. Both thermal and tactile hypersensitivities were permanently reversed at the highest doses of GABA. However, if GABA was injected any later than 2-3 weeks after nerve injury, it was ineffective to prevent such hypersensitivity. This suggests that altered spinal GABA levels contribute to the induction phase of chronic neuropathic pain and that early intervention to restore GABA may prevent the development of that pain.

Animals↗
PubMed1999

Melatonin blocks the activation of estrogen receptor for DNA binding.

The present study shows that melatonin prevents, within the first cell cycle, the estradiol-induced growth of synchronized MCF7 breast cancer cells. By using nuclear extracts of these cells, we first examined the binding of estradiol-estrogen receptor complexes to estrogen-responsive elements and found that the addition of estradiol to whole cells activates the binding of the estrogen receptor to DNA whereas melatonin blocks this interaction. By contrast, melatonin neither affects the binding of estradiol to its receptor nor the receptor nuclear localization. Moreover, we also show that addition of estradiol to nuclear extracts stimulates the binding of estrogen receptor to DNA, but this activation is also prevented by melatonin. The inhibitory effect caused by melatonin is saturable at nanomolar concentrations and does not appear to be mediated by RZR nuclear receptors. The effect is also specific, since indol derivatives do not cause significant inhibition. Furthermore, we provide evidence that melatonin does not interact with the estrogen receptor in the absence of estradiol. Together, these results demonstrate that melatonin interferes with the activation of estrogen receptor by estradiol. The effect of melatonin suggests the presence of a receptor that, upon melatonin addition, destabilizes the binding of the estradiol-estrogen receptor complex to the estrogen responsive element.

Base Sequence↗
PubMed1999

Toxicokinetics and oral bioavailability of fumonisin B1.

The kinetics of fumonisin B1 (FB1) after single doses of 10 mg FB1/kg (po) or 2 mg FB1/kg (i.v.) were studied in male Wistar rats. Serial blood samples were obtained after p.o and i.v. administration. Liver and kidney tissue samples were also obtained after p.o administration. Plasma, liver and kidney concentrations of FB1 were determined by a reversed-phase high-performance liquid chromatographic assay using precolumn 0-phthaldialdehyde derivatisation with fluorescence detection. The FB1 plasma profile could be adequately described by a 2-compartment open model. For FB1, the elimination half-life from plasma was 1.03 h after i.v. and 3.15 h after p.o administration. The apparent volume of distribution and volume of distribution at steady state for FB1 were 0.11 and 0.072 L, respectively, after i.v. administration. The total plasma clearance of FB1 was the same for both the p.o and i.v. routes, 0.072 L/h. After the single p.o dose, FB1 was rapidly absorbed with a Tmax of 1.02 h. The maximum plasma concentration of FB1 was 0.18 microgram/mL. The p.o bioavailability of FB1 was 3.5%. The tissue concentration time data for FB1 fit a 1-compartment open model. Considerable concentrations of FB1 were found in the liver and kidney tissues. The elimination half-lives for FB1 were longer for liver (4.07 h) and kidney (7.07 h) than for plasma (3.15 h). Tissue accumulation of FB1 was evidenced by the tissue/plasma area under the concentration-time curve (AUC) ratios; the AUCtissue/AUCplasma for FB1 was 2.03 in liver and 29.89 in kidney.

Administration, Oral↗
PubMed1999

Lumbar transplant of neurons genetically modified to secrete galanin reverse pain-like behaviors after partial sciatic nerve injury.

The use of cell lines as biologic "minipumps" to chronically deliver antinociceptive molecules such as the peptide galanin near the pain processing centers of the spinal cord after nerve injury is a newly developing technology for the treatment of neuropathic pain. The neuronal rat cell line, RN33B, derived from E13 brainstem raphe and immortalized with the SV40 temperature-sensitive allele of large T antigen (tsTag), was transfected with rat preprogalanin (GAL) cDNA and the galanin-synthesizing and -secreting cell line, 33GAL.19, was isolated [1]. The 33GAL.19 cells transfected with the GAL gene expressed immunoreactivity (ir) for the GAL protein and synthesized low levels of GAL-ir at permissive temperature (33 degrees C), when the cells were proliferating, and increased GAL-ir during terminal differentiation at non-permissive temperature (39 degrees C) in vitro. A control cell line, 33V.1, RN33B cells transfected with the pCEP4 vector alone and similarly isolated by subcloning, contained no detectible GAL-ir at either temperature in vitro. These cell lines were used as grafts in a model of chronic neuropathic pain induced by unilateral chronic constriction injury (CCI) of the sciatic nerve. Pain-related behaviors, including cold and tactile allodynia and thermal and mechanical hyperalgesia, were evaluated in the affected hindpaw after CCI and transplants. The 33GAL.19 and 33V.1 cells transplanted in the lumbar subarachnoid space near the spinal cord one week after CCI, survived at least seven weeks on the pial surface around the spinal cord and only the 33GAL.19 cells expressed GAL-ir in vivo after transplant. Furthermore, the tactile and cold allodynia and tactile and thermal hyperalgesia induced by CCI was significantly reduced or eliminated during the two to seven week period after grafts of 33GAL.19 cells. The maximal effect on chronic pain behaviors with the GAL grafts occurred one to three weeks after transplantation. Transplants of 33V.1 control cells had no effect on the allodynia and hyperalgesia induced by CCI. These data suggest that a chronically applied, low local dose of galanin supplied by transplanted cells near the lumbar spinal dorsal horn was able to reverse the development of chronic neuropathic pain following CCI. The use of transplants of genetically modified neural cell lines that are able to deliver antinociceptive molecules, such as galanin, offers a safe and novel approach to pain management.

Animals↗
PubMed1998

Changes in GAD- and GABA- immunoreactivity in the spinal dorsal horn after peripheral nerve injury and promotion of recovery by lumbar transplant of immortalized serotonergic precursors.

We have utilized RN46A cells, an immortalized neuronal cell line derived from E13 brainstem raphe, as a model for transplant of bioengineered serotonergic cells. RN46A cells require brain-derived neurotrophic factor (BDNF) for increased survival and serotonin (5HT) synthesis in vitro and in vivo. RN46A cells were transfected with the rat BDNF gene, and the 46A-B14 cell line was subcloned. These cells survive longer than 7 weeks after transplantation into the subarachnoid space of the lumbar spinal cord and synthesize 5HT and BDNF. Chronic constriction injury (CCI) of the sciatic nerve was used to induce chronic neuropathic pain in the affected hindpaw in rats. Transplants of 46A-B14 cells placed 1 week after CCI alleviated chronic neuropathic pain, while transplants of 46A-V1 control cells, negative for 5HT and without the BDNF gene, had no effect on the induction of thermal and tactile nociception. When endogenous cells of the dorsal horn which contain the neurotransmitter gamma-aminobutyric acid (GABA) and its synthetic enzyme glutamate decarboxylase (GAD) were immunohistochemically quantified in the lumbar spinal cord 3 days and 1-8 weeks after CCI, the number of GABA- and GAD-immunoreactive (ir) cells decreased bilateral to the nerve injury as soon as 3 days after CCI. At 1 week after CCI, the number of GABA-ir cells continued to significantly decline bilaterally, returning to near normal numbers on the side contralateral to the nerve injury by 8 weeks after the nerve injury. The number of GAD-ir cells began to increase bilaterally to the nerve injury at 1 week after CCI and continued to significantly increase in numbers over normal values by 8 weeks after the nerve injury. When examined 2 and 8 weeks after CCI plus cell transplants, the transplants of 46A-B14 cells reversed the increase in GAD-ir cell numbers and the decrease in GABA-ir cells by 1 week after transplantation, while 46A-V1 control cell transplants after CCI had no effect on the changes in numbers of GAD-ir or GABA-ir cells. Collectively, these data suggest that altered 5HT levels, and perhaps BDNF secretion, related to the transplants ameliorate chronic pain and reverse the induction and maintenance of an endogenous pain mechanism in the dorsal horn. This induction mechanism is likely dependent on altered GAD regulation and GABA synthesis, initiated by CCI.

Animals↗
PubMed1998

Ofuji's papuloerythroderma following choledocholithiasis with secondary sepsis: complete resolution with surgery.

We describe a case of Ofuji's papuloerythroderma (PE) in a 72-year-old man with biliary sepsis induced by choledocholithiasis. The PE disappeared completely after surgery with no relapse. This aetiology for PE does not appear to have been described previously, while its resolution after treatment of the primary process supports the idea that it may be a reactive disorder of multifactorial origin.

Aged↗