Photoinhibition of the quantum confined Stark effect in piezoelectric multiple quantum wells.
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Journal Article↗
Biomedical subjects
M López
Publications and source records attributed to M López.
Molecular analysis in true hermaphrodites with different karyotypes and similar phenotypes.
True hermaphroditism is characterized by the development of ovarian and testicular tissue in the same individual. Müllerian and Wolffian structures are usually present, and external genitalia are often ambiguous. The most frequent karyotype in these patients is 46,XX or various forms of mosaicism, whereas 46,XX is very rarely found. The phenotype in all these subjects is similar. We studied 10 true hermaphrodites. Six of them had a 46,XX chromosomal complement: 3 had been reared as males and 3 as females. The other 4 patients were mosaics: 3 were 46,XX/46,XY and one had a 46,XX/47,XXY karyotype. One of the 46,XX/46,XY mosaics was reared as a female, whereas the other 3 mosaics were reared as males. The sex of assignment in the 10 patients depended only on labio-scrotal differentiation. Molecular studies in 46,XX subjects documented the absence of Y centromeric sequences in all cases, arguing against hidden mosaicism. One patient presented Yp sequences (ZFY+, SRY+), which contrast with South African black 46,XX true hermaphrodites in whom no Y sequences were found. Molecular analysis in the subjects with mosaicism demonstrated the presence of Y centromeric and Yp sequences confirming the presence of a Y chromosome. Gonadal development, endocrine function, and phenotype in the 10 patients did not correlate with the presence of a Y chromosome or Y-derived sequences in the genome, confirming that true hermaphroditism is a heterogeneous condition.
Adolescent↗
Mitochondrial differentiation during the early development of the brine shrimp Artemia franciscana.
During the early development of Artemia there is an increase in mitochondrial enzyme activities of about one order of magnitude, whereas the activities of two cytoplasmic enzymes tested as controls remain unaltered. The mitochondrial enzyme activation correlates with (i) large changes in mitochondrial morphology, (ii) a 5-fold increase in the amount of the H+-ATP synthase beta-subunit and (iii) a dramatic increase in the steady-state level of mitochondrial mRNAs, whereas mitochondrial rRNA concentrations remain mostly unchanged. In contrast, the level of mitochondrial DNA does not change significantly during the first 20 h after resumption of development. After hatching, the mitochondrial DNA content increases twice in parallel with one round of cellular division, thus indicating that mitochondrial and nuclear replication are coupled in Artemia postgastrular development. The data presented strongly suggest that mitochondrial maturation in the absence of significant mitochondrial proliferation is responsible for the dramatic increase in mitochondrial function that takes place after resumption of development in Artemia.
Adenosine Triphosphatases↗
Successful bone marrow transplantation in sensitized aplastic anemia patients using total lymphoid irradiation for conditioning: long-term follow-up.
Between June 1986 and November 1994, 22 previously transfused patients with severe aplastic anemia (SAA) were treated with high-dose cyclophosphamide (CY) (50 mg/kg over 4 consecutive days) and 7 Gy total lymphoid irradiation (TLI) in two fractions before allogeneic bone marrow transplantation (BMT) from HLA-identical sibling. Graft-versus-host-disease (GVHD) prophylaxis included the combination of methotrexate and cyclosporine A in all cases. Actuarial survival at 5 years is 73 +/- 9 per cent for the entire group and 86 +/- 13 per cent for the seven patients < or = 18 years. The incidence of graft failure was 0 per cent, and of acute GVHD and chronic GVHD was 31.5 per cent and 24 per cent respectively. Prolonged interval from diagnosis to BMT adversely influenced survival (P = 0.03). No hypothyroidism or secondary malignancies have been documented in this series. Our findings indicate that survival with CY-TLI is comparable to that obtained using preparative regimens without radiation. The changing role of radiotherapy in pretransplant immunosuppression for SAA is discussed.
Adolescent↗
Effect on pH heating medium on the thermal resistance of Bacillus stearothermophilus spores.
The influence of the pH of heating medium on heat resistance of Bacillus stearothermophilus spores (ATCC 7953, 12980, 15951 and 15952) were studied. The pH values tested were: 4.0, 5.0, 6.0 and 7.0 at temperatures of 115, 120, 125, 130 and 135 degrees C. It was found that at low treatment temperatures (115 degrees C) D-values decreased between 7- and 10-fold with 7953, 12980 and 15951 strains and about 23-fold with 15952 strain when pH dropped from 7.0 to 4.0. At highest treatment temperatures (135 degrees C) D-values obtained with pH 6.0 and 7.0 did not show any significant statistical differences (p > 0.05). z-Values appeared to be higher when the medium was acidified, ranging from 7.58 to 8.20 and 9.43 10.0 for spores suspended in McIlvaine buffer pH 7.0 and pH 4.0, respectively, although the difference was not statistically significant. Heat resistance of strain ATCC 7953 at 120, 128, and 135 degrees C in asparagus purée and tomato purée at pH 5.0 under continuous monitoring of pH was also determined. D-values obtained in asparagus purée were similar to those obtained in buffer at the same pH, whereas those observed in tomato purée were found to be lower.
Culture Media↗
Effect of pH of the recovery medium on the apparent heat resistance of three strains of Bacillus cereus.
The influence of pH of the recovery medium, in the range 7.6-5.4, on the apparent heat resistance of three strains of Bacillus cereus (ATCC 4342, 7004 and 9818) has been investigated. The highest counts of heat-injured spores were obtained at pH near neutral, decreasing markedly as pH was reduced, especially with longer heating times. When the media were acidified, the apparent D-values tended to decrease, although some exceptions related to the strain and the nature of the medium were observed. z-Values determined were not affected by the pH of the medium.
Bacillus cereus↗
Interleukin 1 and tumor necrosis factor in obese alcoholics compared with normal-weight patients.
We performed a liver biopsy and measured plasma concentrations of interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha), and spontaneous and lipopolysaccharide-stimulated in vitro monocyte production of IL-1 beta and TNF-alpha in 19 obese and 17 age-matched, normal-weight alcoholics admitted for treatment of their alcoholism. Nine healthy normal-weight alcoholics had cirrhosis in their liver biopsy (Fisher's exact test: P=0.031). A histologic score (derived from the sum of fat, necrosis, fibrosis, and inflammation in the biopsy) correlated with body mass index and the percentage body fat, calculated by using the sum of four skinfold-thickness measures. Plasma concentrations and spontaneous in vitro monocyte production of IL-1 beta and TNF-alpha were below detection limits. No significant differences were observed between normal-weight and obese alcoholics with or without cirrhosis and normal control subjects in lipopolysaccharide-stimulated monocyte production of IL-1 beta (6.5 +/- 0.8, 10.1 +/- 2.7, 7.9 +/- 1.6, and 5.28 +/- 4.24 micrograms/L, respectively) or TNF-alpha (2.8 +/- 0.4, 3.7 +/- 1.0, 3.0 +/- 0.44, and 1.97 +/- 1.01 micrograms/L, respectively). However, a positive correlation was found between IL-1 beta production and body mass index (r=0.333, P=0.047), percentage body fat (r=0.412, p=0.013), abdominal circumference (r=0.416, P=0.012), and total histologic score (r=0.331, P=0.049). A multiple-regression model accepted abdominal circumference as the only independent predictor of IL-1 beta production. TNF-alpha did not correlate with any of the above-mentioned indexes. We conclude that obese alcoholics have a higher frequency of histologic liver damage and that IL- 1 beta production by stimulated monocytes is related to abdominal fat accumulation.
Adult↗
Thermal resistance of Bacillus stearothermophilus spores in different heating systems containing some approved food additives.
The effects of different heating systems on the heat resistance of Bacillus stearothermophilus spores (ATCC 7953, 12980, 15951 and 15952) were investigated. Spores were heated in distilled water, Sorensen buffer (0.18 mol 1-1), McIlvaine buffer (0.0025-0.18 mol 1-1), and several solutions containing sodium chloride (0.06-12%), sodium nitrite (125 ppm), potassium sorbate (0.1%) and sodium benzoate (0.1%) over a wide range of temperatures (115-140 degrees C). D-values obtained for McIlvaine and Sorensen buffers, at the same molarities, were not significantly different (P > 0.05), but decimal reduction times increased as phosphate concentrations in the solutions decreased. The concentrations, in which statistically significant differences (P < 0.05) were obtained, varied among strains. Among the additives assayed, only sodium chloride reduced heat resistance, being effective at concentrations as low as 0.06%. The z-values calculated in this study ranged from 6.99 to 8.40 with a mean value of 7.60 +/- 0.45. Although z-values observed for salt and buffers (180 mol 1-1) were slightly higher than obtained in the other conditions assayed, the difference was not statistically significant (P > 0.05).
Benzoates↗
Age-related differences in the glomerular and renal tubular effects of amikacin in the rat.
Several biological responses to drugs are dependent on the age of the individual. Renal excretion of amikacin occurs mainly through glomerular filtration and this function is diminished in the young animal. We evaluated the renal response to amikacin in the unanesthetized infant rat (21-day-old) and we compared it with that of the adult rat. Either amikacin (7.5 and 75.0 mg/kg body weight, i.m.) or vehicle were administered to infant rats and the effects on sodium, potassium and water balance were assessed. Creatinine clearance (Ccr) was calculated. Amikacin induced an increment in sodium absolute excretion, whereas the Ccr decreased. In the infant rat the effects were more marked. Changes in FENa were more marked than those in Ccr, suggesting a direct effect of amikacin on the tubular reabsorption of electrolytes in addition to deleterious effects on glomerular dynamics. Our results suggest that amikacin induces more changes in renal function in the infant than in the adult rat and therefore it might be convenient to carefully evaluate the renal condition in the patients that receive this drug.
Aging↗
Severe hypertriglyceridemia post-renal graft: is there a relationship with infection by cytomegalovirus?
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Case-Control Studies↗
[Treatment of the regional lymph nodes in squamous carcinoma of the penis].
OBJECTIVES: We evaluated the management of the regional lymph nodes to determine the appropriate treatment for carcinoma of the penis. METHODS: The records of 36 patients with carcinoma of the penis were reviewed. Lymphadenectomy was performed in 18 patients, 17 were managed conservatively (watchful waiting) and 1 patient had a biopsy and received radiotherapy. RESULTS: Positive nodes were found in 2 of 2 pT4, 2 of 3 pT3, 8 of 13 pT2 and 2 of 12 pT1 patients submitted to lymphadenectomy. Concerning the histological grade, positive nodes were found in all of the 4 G3, 5 of 12 G2 and 3 of 20 G1 patients. The survival rate was 100% for the patients with negative lymph nodes (pNO = 6) or a single positive inguinal lymph node (pN1 = 5). A correlation was found between the T and the histological grade and the likelihood of lymph node invasion. CONCLUSIONS: The T and the histological grade of the primary lesion must be considered when deciding the approach in the management of the lymph nodes as unnecessary lymphadenectomy can be avoided and those at high risk of lymph node invasion can be treated radically and timely.
Adult↗
[Correlation between specific prostatic antigen and findings with total body bone scintigraphy].
OBJECTIVES: To analyze the correlation between PSA values, bony symptoms and total body bone scintiscanning in order to determine the utility of the latter technique in patients with adenocarcinoma of the prostate. METHODS: We analyzed the correlation between the PSA values, bony symptoms and total body bone scintiscan findings of 191 patients with adenocarcinoma of the prostate; of these, 129 patients met the criteria for inclusion into the study. RESULTS: Of the 128 patients, 32 (25%) had PSA value < 20 ng/ml, 48 (37.5%) had values ranging from 20-50 ng/ml and 48 (37.5%) had values > 50 ng/ml. The bone scintiscan was positive in only one of the 32 patients with PSA < 20 ng/ml, 45.8% of those with PSA values between 20-50 ng/ml and 70.8% of those with PSA values > 50 ng/ml. All of the patients with PSA < 20 ng/ml and no bony symptoms had a negative bone scintiscan. All patients with PSA > 20 ng/ml and bony symptoms had a positive bone scintiscan. CONCLUSIONS: PSA is a biological marker that can effectively predict the scintiscan findings. The bone scintiscan was negative in 96.9% of the patients with PSA < 20 ng/ml. Total body bone scintiscanning can therefore be obviated in patients with PSA < 20 ng/ml and no bony symptoms, thereby reducing health costs without altering the benefits.
Adenocarcinoma↗
SRY alone can induce normal male sexual differentiation.
Most individuals with the rare 46,XX male "syndrome" arise due to an unequal interchange between Xp and Yp termini during paternal meiosis. The pattern of Y-sequences in these patients varies considerably, but very few cases have been reported showing only SRY. The phenotype in these patients is also variable ranging from severe impairment of the external genitalia through hypospadias and/or cryptorchidism to occasional normal male phenotype. We report a Mexican 46,XX male patient without genital ambiguities in whom DNA analysis showed the presence of SRY and the absence of ZFY. We conclude that in this case SRY alone was enough for complete male sexual differentiation.
DNA-Binding Proteins↗
Electrophoretic karyotype of the astaxanthin-producing yeast Phaffia rhodozyma.
The electrophoretic karyotype of three different strains of Phaffia rhodozyma was determined by contour-clamped homogeneous electric field (CHEF)-gel electrophoresis. Significant differences in electrophoretic karyotyping patterns were found among the three strains studied. Between nine and 17 bands were observed. The size of these bands, based on their migration relative to the chromosomal DNA of Schizosaccharomyces pombe, Hansenula wingei was estimated to be between 0.48 and 3.1 Mb.
Carotenoids↗
Role of protein kinase C on the acute desensitization of renal cortical adenylate cyclase to parathyroid hormone.
The mechanisms of adenylate cyclase desensitization to parathyroid hormone are still unclear. Current evidence suggest that the signal generated after PTH binding to receptors results in activation of adenylate cyclase and stimulation of phospholipase C with subsequent activation of protein kinase C. Recent studies have suggested a role of protein kinase C on the regulation of the PTH-dependent receptor-adenylate cyclase system in cultured cells. Therefore, the present studies were conducted to examine the role of protein kinase C on the desensitization of canine renal cortical adenylate cyclase after an acute exposure in vivo to PTH. A group of normal dogs were treated with a single intravenous injection of 1 microgram/k of syn bPTH (1-34) or Nle bPTH (3-34). Ten minutes later, animals were subjected to bilateral nephrectomy and the kidney cortex processed for preparations of basolateral membranes for determinations of adenylate cyclase activity, as well as membrane and cytosolic fractions for analysis of protein kinase C activity. Animals not treated with PTH were used as controls. PTH administration in vivo resulted in a 46.9 +/- 9.3% decrease in maximal adenylate cyclase activity in vitro in response to syn bPTH (1-34) (P < 0.001). Likewise, PTH binding as measured with 125I-Nle8,18,Tyr34-bPTH (1-34)NH2 showed a 40 +/- 3% decrease. This alterations were associated with a marked translocation of protein kinase C from the cytosol to the membrane. Thus, protein kinase C activity in membrane fractions increased from 160.6 +/- 44.8 pmol Pi/min in controls to 500.4 +/- 123 in PTH treated dogs (P < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)
Adenylyl Cyclases↗
Clinical traits and molecular findings in 46,XX males.
46,XX maleness is characterized by the presence of testicular development in subjects who lack a Y chromosome. The majority of affected persons have normal external genitalia, but 10-15% show various degrees of hypospadias. Several hypotheses have been proposed to explain the etiology of this constitution: translocation of the testis-determining factor (TDF) from the Y to the X chromosome, mutation in an autosomal or X chromosomal gene which permits testicular determination in the absence of TDF, and undetected mosaicism with a Y-bearing cell line. We report the phenotypic data and results of molecular analyses performed in six sporadic Mexican males with 46,XX karyotype. Molecular studies revealed Yp sequences in two individuals (ZFY+ SRY+) with different phenotypes, a third one presented with a smaller segment of Yp (ZFY- SRY+) and complete virilization, while the remaining three were Y-negative and showed hypospadias. In all subjects a hidden mosaicism with a Y-bearing cell line was ruled out due to the absence of Y-centromeric sequences. Our data demonstrate that the phenotype does not always correlate with the presence or absence of Y-sequences in the genome, and confirm that 46,XX maleness is a genetically heterogeneous condition.
Adolescent↗
Different effects of fibrates on the microsomal fatty acid chain elongation and the acyl composition of phospholipids in guinea-pigs.
1. The effects in vitro and in vivo of three fibric acid derivatives, clofibrate (CFB), bezafibrate (BFB) and gemfibrozil (GFB) on some enzyme activities related to fatty acid biosynthesis, namely palmitoyl-CoA synthetase and hydrolases (microsomal and cytosolic), NADH and NADPH cytochrome c reductases and acyl-CoA elongases were investigated in guinea-pigs. 2. The three fibrates inhibited acyl-CoA elongation in vitro, irrespective of the substrate of elongation used (saturated, monounsaturated, polyunsaturated) and with an order of potency GFB > BFB > CFB. In the case of GFB, inhibition occurred at concentrations that can be reached in vivo. 3. Microsomal palmitoyl-CoA hydrolase and synthetase were also inhibited in vitro (GFB > or = BFB > CFB), whereas NADH cytochrome c reductase activity was increased by GFB. Nevertheless, the magnitude of changes were lower than those observed in elongation activities. 4. Treatment with fibrates did not produce peroxisomal proliferation in guinea-pigs, as measured by peroxisomal beta-oxidation activity and liver weight/body weight ratio. Nevertheless, fibrates provoked a reduction in plasma cholesterol and triglycerides, at least in GFB- and BFB-treated animals. 5. Fatty acid elongation was significantly modified by GFB treatment in vivo. The remaining enzyme activities studied were only slightly changed by fibrate treatment. 6. Treatment with BFB and to a lesser extent with CFB, increased the relative proportion of MUFA (palmitoleic and oleic acids) in microsomal phospholipids, whereas PUFA (mainly linoleic acid) decreased. GFB behaved differently, increasing palmitic and linoleic acids and decreasing stearic and oleic acids. The latter changes are attributable to an inhibition of elongation activity by GFB. 7. The changes observed after fibrate treatment in both rats and guinea-pigs, as they are not directly related to peroxisome proliferation, could be more reliably extrapolated to man than those observed only in rats.
Animals↗
[Biochemical indicators of primary graft dysfunction in experimental orthotopic liver transplantation].
Aiming at investigating biochemical markers of Primary Graft Nonfunction (PNF) in Orthotopic Liver Transplantation (OLT) an experimental work is made on 21 Large-White pigs randomly distributed in three groups of seven, and two additional groups of seven donors each. In Group I the supra and infrahepatic cava, the portal vein and the hepatic artery were clamped. After 30 minutes the caval and portal clamps were released and 30 minutes later the arterial clamp was also removed. In Group II (viable), OLT was performed. The Collins solution was used as preservation fluid, keeping the cold ischemia time under 2 hours. In Group III (Non-Viable), an OLT was carried out 24 hours of cold ischemia with Collins solution. Blood samples are taken in 8 different moments along the procedure to determinate the values of AST, ALT, LDH, FA, Bilirubin, Uric Acid, Cholesterol, Triglycerides, Urea, Creatinine, Glucose, Total Protein, Calcium, Phosphorus, CPK and Aldolase. The last 5 samples were drawn after reperfusion. In the Group III we found, in the samples drawn after reperfusion of the graft, significant increases in 5 of these parameters, AST, ALT LDH, Aldolase and Uric Acid. We consider that these 5 parameters may be of value in the early diagnosis of PNF of the graft, being the AST and ALT the most reliable, with the higher specificity for the same sensitivity.
Alanine Transaminase↗