PubMed Health⌕ Search

Biomedical subjects

M T Martinez

Publications and source records attributed to M T Martinez.

13 recordsLinked to original sources
PubMed2005

Transplant-associated microangiopathy (TAM) in recipients of allogeneic hematopoietic stem cell transplants.

We studied occurrence, risk factors and outcome of patients with transplant-associated microangiopathy (TAM) after allogeneic stem cell transplantation (HSCT). A total of 221 consecutive patients were transplanted between 1995 and 2002. TAM is defined as evidence of hemolysis and schistocytes in the first 100 days. Outcomes analyzed included TAM and overall survival. Of 221 patients, 68 had TAM. The cumulative incidence was 31 (25-38)% at 100 days. Patients with TAM had higher LDH, higher bilirubin, higher creatinine and more often neurologic symptoms. TAM was not associated with stem cell source, cyclosporine levels and was not more frequent in recent years. In multivariate analysis, risk factors for TAM included donor type, age, gender, ABO-incompatibility and acute graft-versus-host disease (aGvHD). In patients with TAM, 1-year survival was lower than in patients without TAM (27 +/- 18% for TAM with high schistocyte counts; 53 +/- 15% for TAM with low schistocyte counts; vs 78 +/- 7% in patients without TAM; P<0.0001). TAM was independently associated with mortality adjusting for donor type, age and aGvHD occurrence and severity. TAM is frequent after HSCT and is associated with mortality even after adjustment for aGvHD grade. Risk factors of TAM are similar to aGvHD. TAM may represent endothelial damage driven by donor-host interactions.

Adolescent↗
PubMed1997

Construction of a gene encoding the insect bactericidal protein attacin. Studies on its expression in Escherichia coli.

Attacin, a bactericidal small protein is produced by the giant silk moth Hyalophora cecropia. This paper deals with our efforts to clone the attacin cDNA in a bacterial vector to express it in Escherichia coli and produce the protein in sufficient amount, for further studies. We chose two inducible expression vector/bacterial cell systems: pPL-lambda/N99cI+ cells which is able to be induced by nalidixic acid, and pET3d/BL21(DE3) cells carrying a T7 RNA polymerase gene which is IPTG-inducible. After cloning in the pPL-lambda system and under no addition of the inducer, isolated transformants carried this plasmid with at least 2 concurrent deletions that drastically affected attacin expression, even though attacin gene seems to be intact as deduced by its PCR amplification. It was concluded that basal attacin expression occurred in this system and bacterial growth was limited. Plasmid deletions may have emerged by selection pressure as a way to avoid bactericidal expression and allow bacteria survival. The second cloning attempt was done in pET3d vector/BL21 cells, that should not express the cloned sequence (they lack T7 RNA polymerase gene). Transformed BL21 cells gave 3 recombinant plasmids, 2 of them presented a C deletion that generated an early stop signal in the attacin coding region. The third clone, pET-ATT18, carrying an intact gene, was transferred to BL21(DE3)-IPTG inducible cells in order to be expressed. Attacin was undetectable in stained gels or by Western blot analysis. However, expression was visualized in grown cells after 30 min of IPTG induction and 5 min of [35S]-methionine labeling, as a 22.5 kDa protein band by using gel electrophoresis and fluorography. This low level of expression drastically affected bacterial growth. Considering that attacin has no lytic activity, these results suggest that this molecule should block bacterial growth directly at the cytoplasm by an unknown mechanism, since no signal peptide coding sequence was incorporated in this gene construction, precluding periplasmic or external destination of this protein.

Anti-Bacterial Agents↗
PubMed1996

Genetic predisposition and environmental factors leading to the development of insulin-dependent diabetes mellitus in Chilean children.

This study was designed to examine the hypothesis that some environmental factors increase the risk for insulin-dependent diabetes mellitus. Data on dietary history was collected from 80 diabetic children from the Santiago de Chile Registry and from 85 nondiabetic control subjects who were comparable in terms of age, sex, and ethnic characteristics. Early exposure was defined as the ingestion of food sources other than maternal milk before 3 months of age. To define genetic susceptibility to insulin-dependent diabetes mellitus each subject was typed in terms of HLA DQA1 and DQB1, and the possible conformation of susceptible heterodimers was considered as a risk marker. Fewer children were exclusively breast fed in the diabetic group than in the control group (21.55 +/- 15.05 vs 33.95 +/- 20.40 weeks, P<0.01). In addition, exposure to cow's milk and solid foods occurred earlier in the diabetic group than in the control group (15.90 +/- 10.95 vs 21.15 13.65 and 16.85 +/- 10.25 vs 21.20 +/- 12.35 weeks, P<0.05). Our data show that a short duration of breast-feeding and early exposure to cow's milk and solid foods may be important factors in the development of insulin-dependent diabetes mellitus. The high relative risk observed in individuals genetically predisposed indicates an interaction effect between genetic and environmental components.

Adolescent↗
PubMed1994

Perilymphatic fistulas.

Perilymphatic fistula (PLF) is an abnormal connection between the inner ear and middle ear space which allows the escape of perilymph and may result in disorders of hearing, balance, or both. This entity has received considerable attention and is a major area of interest and controversy in modern otology. The clinical manifestations of this condition are variable and encompass the whole spectrum of audiovestibular signs and symptoms. The diagnostic criteria have yet to be established. Currently there is no consistent objective preoperative test to diagnose PLF. Definitive diagnosis is made on middle ear exploration and rests on the observation of the surgeon. There is no objective intraoperative test to confirm the presence of PLF. The purpose of this paper is to present the classification system and current understanding of the pathogenesis of PLF. In addition, clinical manifestations, evaluation, and management of patients with this otologic entity will be reviewed.

Ear, Middle↗
PubMed1992

Characterization of acetylcholinesterase and butyrylcholinesterase activities in retinal chick pigment epithelium during development.

The presence of acetylcholinesterase and butyrylcholinesterase was studied in chick retinal pigment epithelium. Acetylcholinesterase activity was 13 times higher than that of butyrylcholinesterase. The former showed a Km of 290 microM and a vmax of 45.4 nmol mg-1 protein min-1, while the latter showed two apparent Km values (132 microM and 666 microM). Studies on subcellular distribution revealed that both enzymes are associated with membranes. During the embryonic development butyrylcholinesterase activity decreased, while acetylcholinesterase activity increased. The possibility that these changes are related to the proliferation and differentiation processes is discussed.

Acetylcholinesterase↗
PubMed1989

Epidemiology of fractures of the proximal femur associated with osteoporosis in Barcelona, Spain.

We studied the epidemiology of osteoporotic fractures of the proximal femur (cervical and trochanteric fractures) in residents of Barcelona, aged 45 years or over, for a 1-year period. Fractures resulting from metastases were not included. During the period of observation, a total of 1,358 patients with hip fractures were treated at acute-care hospitals in Barcelona. Of those, 1,163 were researched. For each case, age, sex, and home address were registered. The incidence of hip fractures per 100,000 inhabitants aged 45 years or over was 115.6 in men and 252.2 in women. Age was the most influencing factor in the occurrence of hip fractures. Women presented fractures of the proximal femur more frequently than men. The epidemiological curve was similar to that reported in other western countries, although the crude rate was lower than that found in northern countries. We conclude that osteoporotic fractures of the proximal femur are common processes in the Mediterranean area, and reflect the impact of osteoporosis in our environment; however, the lower incidence compared with northern geographical areas may probably reflect the influence of climatic, ethnic, or other factors.

Aged↗
PubMedDate not supplied

True prophylactic gentamicin application in experimental Pseudomonas keratitis.

In an experimental model of Pseudomonas keratitis, 50 rabbit eyes were treated with gentamicin sulfate (3 mg/mL) prophylactically on four different treatment regimens. One group (13 eyes) received one drop of gentamicin sulfate every hour to a total of four drops, the last drop 25 minutes before inoculation. A second group (13 eyes) was given one drop of gentamicin sulfate one hour before inoculation. A third group (12 eyes) received one drop of gentamicin sulfate per minute to a total of 4 drops, the last drop 25 minutes prior to inoculation. A fourth group (12 eyes) received one drop of antibiotic 25 minutes before inoculation. Twelve control eyes received saline solution. Subsequently, a superficial corneal scratch was inflicted and each eye received one drop (0.05 mL) of a solution containing Pseudomonas aeruginosa. The infection rate in all four experimental groups was low, whereas all control eyes became infected. These results demonstrate the effectiveness of prophylactic antibiotic application in the prevention of Pseudomonas keratitis prior to superficial ocular trauma.

Animals↗
PubMedDate not supplied

Lipoprotein (a) and other risk factors in children with insulin-dependent diabetes mellitus and children without diabetes.

AIMS: To study serum Lp(a) levels and other metabolic cardiovascular risk factors in children with Type 1 diabetes mellitus (DM) compared to sex and age matched nondiabetic children. The correlation of Lp(a) serum levels and other lipid parameters with HbA1c concentrations in diabetic children was investigated. DESIGN: Transversal observational study. TARGET POPULATION: 36 C-peptide negative Type 1 DM children without microalbuminuria and no macromicrovascular or neurological complications, aged 8 to 15 years; 17 boys, 19 girls. Mean duration of Type 1 DM was 4.99 +/- 3.04 years, daily insulin need were 32.79 +/- 12.64 Units. 41 healthy children with no family history of DM, aged from 8 to 15 years, 26 boys, 15 girls, were studied in parallel as the control group. METHODS: Serum total cholesterol (TC) and triglycerides (TG) were assayed by enzymatic methods, high-density lipoprotein (HDL) cholesterol by enzymatic method after precipitation of very-low-density (VLDL) and low-density lipoprotein (LDL) fractions. The LDL fractions was estimated after serum precipitation as the difference between total cholesterol and supernatant cholesterol concentrations. Apo-AI, apo-AII and apo-B were measured by radial immunodiffusion assays. Serum Lp(a) was measured by monoclonal anti-Lp(a) antibody (ELISA) method and whole blood glycosylated hemoglobin A1c (HbA1c) by high resolution liquid chromatography. RESULTS: HbA1c concentration in diabetic children was 7.51 +/- 54% vs 4.16 +/- 0.35% in non diabetic children. Lp(a) serum levels did not significantly differ among both groups (25 +/- 22 mg/dl in diabetics subjects, 22 +/- 22 mg/dl in controls). Significant correlation was found between HbA1c levels and each of TC, LDL and TG serum concentrations in the diabetic group. Lp(a) levels were correlated with glycated hemoglobin in the whole diabetic group. But, in the 2 patients with the poorest metabolic control (HbA1c 10.5%) were excluded, the correlation disappeared. CONCLUSIONS: In 36 children aged 5-15 years with uncomplicated Type 1 DM lasting less than 15 years, Lp(a) serum levels did not differ from age-matched controls but highest Lp(a) values were associated with poorest metabolic control.

Adolescent↗
PubMedDate not supplied

Lipoprotein (a) and other risk factors in children with insulin-dependent diabetes mellitus and children without diabetes.

AIMS: To study serum Lp (a) levels and other metabolic cardiovascular risk factors in children with type 1 diabetes mellitus (DM) as compared to sex and age matched nondiabetic children. The correlation of Lp (a) serum levels and other lipid parameters with HbA1c concentration in diabetic children was investigated. DESIGN: Transversal observational study. TARGET POPULATION: 36 C-peptide negative Type 1 diabetic children without microalbuminuria and no macromicrovascular nor neurological complications, aged 8 to 15 years; 17 boys, 19 girls. Mean duration of Type 1 diabetes was 4.99 +/- 3.04 years, daily insulin needs 32.79 +/- 12.64 Units. 41 healthy children with no family history of diabetes mellitus, aged 8 to 15 years, 26 boys, 15 girls, were studied in parallel as the control group. METHODS: Serum total cholesterol and triglycerides were assayed by enzymatic methods, High-density lipoprotein (HDL) cholesterol by enzymatic method after precipitation of very-low-density (VLDL) and low-density lipoprotein (LDL) fractions. The LDL fraction was estimated after serum precipitation as the difference between total cholesterol and supernatant cholesterol concentrations. Apo-AI, apoA-II and apo-B were measured by radial immunodiffusion assays. Serum Lp(a) was measured by a monoclonal anti-Lp(a) antibody (ELISA) method and whole blood glycosylated hemoglobin A1c (HbA1c) by high resolution liquid chromatography. RESULTS: HbA1c concentration in diabetic children was 7.51 +/- 1.54% vs 4.16 +/- 0.35% in nondiabetic children. Lp(a) serum levels did not significantly differ among both groups (25 +/- 22 mg/dl in diabetics; 22 +/- 22 mg/dl in controls). Significant correlation was found between HbA1c levels and each of TC, LDL and TG serum concentrations in the diabetic group. Lp (a) levels were only correlated with glycated hemoglobin in the two patients showing the highest levels of HbA1c; in the diabetic group: HbA1c 10.9 and 11.5%. CONCLUSIONS: In 36 children aged 8-15 years with uncomplicated Type 1 diabetes for less than 15 years duration, Lp (a) serum levels were positively correlated with HbA1c only in two of them showing the poorest metabolic control.

Adolescent↗