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Biomedical subjects

L Gonzalez

Publications and source records attributed to L Gonzalez.

At least 91 records · Page 5Linked to original sources
PubMed1992

Cofactor and DNA interactions in EcoRI DNA methyltransferase. Fluorescence spectroscopy and phenylalanine replacement for tryptophan 183.

EcoRI DNA methyltransferase contains tryptophans at positions 183 and 225. Tryptophan 225 is adjacent to residues previously implicated in S-adenosylmethionine (AdoMet) binding and to cysteine 223, previously shown to be the site of N-ethyl maleimide-mediated inactivation of the enzyme (Reich, N. O., and Everett, E. (1990) J. Biol. Chem. 265, 8929-8934; Everett, E. A., Falick, A. M., and Reich, N. O. (1990) J. Biol. Chem. 265, 17713-17719). The fluorescence spectra of the wild-type enzyme is centered at 338 nm indicating partial tryptophan solvent accessibility. Substitution of tryptophan 183 with phenylalanine results in a 45% drop in fluorescence intensity, but no shift in lambda max. DNA binding to the wild-type methyltransferase caused an increase in the fluorescence intensity, while binding to the tryptophan 183 mutant had a quenching effect, suggesting that DNA binding induces a conformational change near both tryptophans. Binding of AdoMet and various AdoMet analogs to the wild-type methyltransferase results in no change in the fluorescence spectrum when excitation occurs at 295 nm, suggesting that no conformational change occurs, and AdoMet does not interact with either tryptophan. In contrast, quenching was observed when excitation occurred at 280 nm, suggesting that AdoMet and its analogs may be quenching tyrosine to tryptophan energy transfer. Protein-ligand complexes were titrated with acrylamide, and the data also implicate conformational changes upon DNA binding but not upon AdoMet binding, consistent with previous limited proteolysis results (Reich, N. O., Maegley, K. A., Shoemaker, D.D., and Everett, E. (1991) Biochemistry 30, 2940-2946).

Acrylamide↗
PubMed1991

Calcium supplementation to prevent hypertensive disorders of pregnancy.

BACKGROUND: Calcium supplementation has been reported to reduce blood pressure in pregnant and nonpregnant women. We undertook this prospective study to determine the effect of calcium supplementation on the incidence of hypertensive disorders of pregnancy (gestational hypertension and preeclampsia) and to determine the value of urinary calcium levels as a predictor of the response. METHODS: We studied 1194 nulliparous women who were in the 20th week of gestation at the beginning of the study. The women were randomly assigned to receive 2 g per day of elemental calcium in the form of calcium carbonate (593 women) or placebo (601 women). Urinary excretion of calcium and creatinine was measured before calcium supplementation was begun. The women were followed to the end of their pregnancies, and the incidence of hypertensive disorders of pregnancy was determined. RESULTS: The rates of hypertensive disorders of pregnancy were lower in the calcium group than in the placebo group (9.8 percent vs. 14.8 percent; odds ratio, 0.63; 95 percent confidence interval, 0.44 to 0.90). The risk of these disorders was lower at all times during gestation, particularly after the 28th week of gestation (P = 0.01 by life-table analysis), in the calcium group than in the placebo group, and the risk of both gestational hypertension and preeclampsia was also lower in the calcium group. Among the women who had low ratios of urinary calcium to urinary creatinine (less than or equal to 0.62 mmol per millimole) during the 20th week of gestation, those in the calcium group had a lower risk of hypertensive disorders of pregnancy (odds ratio, 0.56; 95 percent confidence interval, 0.29 to 1.09) and less of an increase in diastolic and systolic blood pressure than the placebo group. The pattern of response was similar among the women who had a high ratio of urinary calcium to urinary creatinine during the 20th week of gestation, but the differences were smaller. CONCLUSIONS: Pregnant women who receive calcium supplementation after the 20th week of pregnancy have a reduced risk of hypertensive disorders of pregnancy.

Blood Pressure↗
PubMed1991

Biomechanical management of children and adolescents with Down syndrome.

The authors describe the podiatric biomechanical management of the child and adolescent with Down syndrome. They also present an overview of the genetics, general characteristics, orthopedic problems, and gait of these patients. They discuss the various approaches to the biomechanical problems associated with the syndrome, and present two case histories that demonstrate common considerations in the treatment of the patient with Down syndrome.

Abnormalities, Multiple↗
PubMed1990

Multiplane gallium tomography in assessment of occupational chest diseases.

Gallium-67 scintigraphy is helpful in the evaluation of inflammatory, respiratory diseases. Single-photon emission computed tomography (SPECT) provides three-dimensional tomographic reconstruction of radioisotope distribution in the body. The addition of SPECT to gallium-67 scanning in 27 patients demonstrated an improvement in the sensitivity for detecting the presence and extent of interstitial occupational lung disease. This technique may provide earlier detection of parenchymal lung changes than can the chest x-ray and planar scanning in some patients with asbestosis. Findings in six patients with asbestosis are reported.

Adult↗
PubMed1990

The development of an evaluation tool for unit-based quality assurance.

A great deal of time, research, and effort was expended in converting the LRMC nursing division from a centralized plan to a decentralized focus. Inherent in the process was the belief that unit-based QA programs offer an excellent opportunity for change, empowering the staff nurse to act as the change agent in improving patient care and enhancing nursing practice. A necessary component in the QA process is evaluation, enabling nurses to step back from the "busyness" of a unit-based committee to identify documented improvements in patient care and to provide validation for changes in nursing practice. The process of evaluation allows nurses the means to appraise the worth and merit of their unit-based QA program. For all levels of nursing, time is a scarce commodity. The realities of the nursing shortage dictate that all programs with staff nurse involvement be examined carefully. For these reasons, thorough and meaningful annual appraisal is critical to ensure that the time spent in implementing and maintaining a unit-based QA program is worth the effort.

Hospital Units↗
PubMed1988

Analgesic efficacy of piroxicam in the treatment of postoperative pain.

Two randomized, double-blind, single-dose studies were conducted to assess the analgesic efficacy and safety of piroxicam for the treatment of moderate or severe postoperative pain. Study 1 evaluated the analgesic efficacy of piroxicam 20 mg compared with that of codeine sulfate 60 mg and placebo. A final patient population of 149 subjects rated pain intensity and pain relief at one half hour and one hour following treatment and then hourly for six hours, with a global assessment made at the completion of 24 hours. Piroxicam 20 mg was significantly more efficacious than placebo for all analgesic variables, including the sum of the pain intensity differences (SPID), total pain relief (TOTAL), percent SPID, duration of effect, and time to remedication. Codeine 60 mg was significantly superior to placebo for percent SPID and some hourly measures. Piroxicam 20 mg was significantly more effective than codeine 60 mg for percent SPID and a few hourly measures including time to remedication. Study 2 assessed the efficacy of piroxicam 20 mg or 40 mg compared with aspirin 648 mg and placebo. Sixty patients rated their pain intensity and relief hourly for 12 hours and at 24 hours after administration of study medication. Both doses of piroxicam were significantly more effective than placebo from Hours 2 to 12 for pain intensity difference (PID) and relief scores, as well as for SPID and TOTAL. Aspirin was significantly more effective than placebo from Hours 2 to 8 for relief and Hours 2 to 10 for PID as well as SPID and TOTAL. Piroxicam 40 mg was significantly more effective than aspirin 648 mg for SPID, TOTAL, and hourly measures beginning with Hour 6 through Hour 12. Piroxicam 20 mg was significantly better than aspirin for a few hourly measures: Hours 7 to 9 for relief and Hour 7 for PID. In addition, effects of piroxicam 20 mg had a significantly longer duration than aspirin. Similarly, piroxicam 20 mg had a significantly longer time to remedication compared with aspirin and placebo. The results of these studies provide evidence in support of the longer duration of analgesic efficacy of piroxicam compared with codeine or aspirin in patients with postoperative pain.

Analgesics↗
PubMed1987

A disease resembling louping-ill in sheep in the Basque region of Spain.

A clinical syndrome resembling louping-ill which primarily affects lambs and yearlings in the Basque region of Spain is described. The disease has been observed for several years during May and June after the sheep flocks have been taken to the mountain grazings where the sheep tick (Ixodes ricinus) is known to occur. Examination of the brain from one of the affected animals revealed histological changes indistinguishable from those caused by louping-ill virus. In addition antibody that reacted with louping-ill virus antigen was detected in the serum of 57 per cent of the sheep tested from the affected flocks but in only 0.8 per cent of sera from flocks free of the disease. These preliminary results suggest that louping-ill or a related tick-borne virus is responsible for ovine encephalomyelitis in Spain.

Animals↗
PubMed1987

Caprine arthritis-encephalitis in the Basque country, Spain.

A goat herd severely affected by arthritis was studied. The most representative clinical signs consisted of articular swelling, mainly of the carpal joints, and the subsequent locomotor disorders. Some goats also showed signs of central nervous system involvement. Examinations of joint fluid revealed an increased number of mononuclear blood cells, mostly lymphocytes. Gross and microscopic articular lesions were of inflammatory and degenerative types. Periarticular connective tissue, synovial bursae, tendons and tendon sheaths were predominantly affected. Inflammatory lesions were those of a chronic hyperplastic tenosynovitis with fibrosis of the connective tissue components. Degenerative changes consisted mainly of necrosis and mineralisation of articular-related structures. Histological lesions in the central nervous system were those of a nonpurulent encephalitis initially located in periventricular areas, but in one case extensive encephalomalacia was also seen. Of the 80 animals sampled 82.5 per cent showed seropositive reactions against an ovine progressive pneumonia virus antigen. None was seropositive to brucella and titres to chlamydia were low. Attempts to isolate chlamydia and mycoplasma from affected joints and several organs failed. Different bacteria were recovered from a few samples but did not seem significant. Syncytium-forming viral particles were isolated from several organs, mainly the lungs, synovial membranes and lymphoid tissue of almost all the slaughtered animals. These particles were identified as lentiviruses by electron microscopy. The clinical signs, lesions serological results and microbiological findings, led to a diagnosis of caprine arthritis-encephalitis. This syndrome has not been recognised in Spain previously.

Animals↗
PubMed1987

Quantitative antimicrobial susceptibility test for Streptococcus pneumoniae using inoculum supplemented with whole defibrinated sheep blood.

The National Committee for Clinical Laboratory Standards recommends the use of lysed horse blood-supplemented Mueller-Hinton broth for determining the quantitative antimicrobial susceptibility of Streptococcus pneumoniae. This procedure may be difficult for laboratories using previously prepared or commercial MIC systems. Therefore, a study was undertaken to determine whether previously prepared microdilution trays containing Mueller-Hinton broth without blood could be used for determining the antimicrobial susceptibility of S. pneumoniae by adding whole defibrinated sheep blood to the bacterial suspension used to inoculate the trays. The presence of alpha-hemolysis was used as an indicator of bacterial growth. One hundred isolates of S. pneumoniae selected to represent a distribution of susceptibility patterns were tested by the National Committee for Clinical Laboratory Standards method and the sheep blood-supplemented-inoculum method. Greater than 94% agreement between the two methods was achieved. The sheep-blood-supplemented-inoculum procedure was highly reproducible and easy to perform and provides an acceptable alternative for determining the MICs for S. pneumoniae for laboratories using previously prepared or commercial microdilution systems.

Culture Media↗
PubMed1983

A grading system for bone marrow cytogenetics and its use as a standard for quality control.

A grading system has been developed to assess the quality of the results of bone marrow cytogenetic procedures. The results of 3 1/2 years use of this grading system are reported. This grading system is a satisfactory internal standard for quality control and is adaptable for use as an external standard. The use of such an internal standard will improve the performance of the cytogenetics laboratory and will validate the quality of the results of cytogenetic examination. The use of an external standard will stimulate the standardization and improvement of cytogenetic laboratory techniques and may be used to develop performance standards for accreditation of both bone marrow and other cytogenetic laboratories. Internal and external quality controls have been used in general medical laboratories for many years, and their use should be instituted by cytogenetic laboratories as well.

Bone Marrow↗
PubMed1980

Acoustic shadow formation by gallstones.

Schlieren photography of gallstones and models of gallstones made from amorphous substances has demonstrated that acoustic shadowing depends primarily on the orientation of the surface of the stone in relation to the sound beam, not the composition of the stone.

Cholelithiasis↗
PubMed1977

Definitive role of CT scanning of the pancreas. The second year's experience.

In a group of 188 patients, 192 computed tomographic (CT) scans of the pancreas were done, and the diagnostic accuracy of CT determined relative to other modalities. CT was the most effective method of detecting neoplastic and inflammatory diseases. The full extent of the disease process, including involvement of the retroperitoneum and metastasis to the liver, was visualized with one examination. Calcification and cystic collections associated with pancreatitis were also clearly seen.

Adenocarcinoma↗