Biomedical subjects
Publications and source records attributed to C Miranda.
Fasting in normal or erythropoietin treated mice results in parallel decrease of erythropoietic activity in spleen and bone marrow. In testosterone-treated animals, starvation only decreases the splenic fraction while the bone marrow erythropoiesis shows a marked increase above normal values.
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The effects of hypoxemia caused by hypoxia (H-H) and CO (H-CO) on the production of erythropoietin (ESF) in mice were investigated. When mice breathed for 6 hr mixtures of air containing 0.1% of CO or a mixture of air and nitrogen with a pO2 of 52 mm Hg, the tissue pO2 as measured by the gas pocket technique was 16.9 +/- 1.1 and 17.1 +/- 1.4 (mean +/- S.D.), respectively. Plasma ESF content in H-CO mice, however, was twice higher than in the H-H mice. The greater ESF production in H-CO was associated to a significantly less hyperventilatory response as measured by acid-base balance changes and to a lower O2 consumption and was interpreted as the result of displacement of the OHb curve in opposite directions. The ESF organ appears thus to be sensitive to variations in the amount of O2 delivered to the tissues but independent of the arterial pO2.
A comparison of the erythropoietic restoring capacity of colony-forming units (CFU) found in the liver of adult mice recovering from a single high dose of cyclophosphamide (CY) with that of CFU derived from fetal liver and from adult bone marrow and spleen was made. In this respect CFU in the liver of adult mice differ notably from CFU in fetal liver but have a striking similarity with adult splenic CFU.
Carbon monoxide injected subcutaneously in mice produces a profound intoxication during a six hour-period. From 2 to 4 hr after the start of carbon monoxide (CO)-hypoxemia large amounts of erythropoietin (ESF) are released in the plasma. Renal extracts obtained at the same time showed higher specific activity than that found in the plasma extracts. No activity was recovered from liver and spleen extracts. Removal of the kidney abolishes totally the production of ESF.
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The zebrafish is a popular model for studies of vertebrate development and toxicology. However, in vitro approaches with this organism have not been fully exploited because cell culture systems have been unavailable. We developed methods for the culture of cells from blastula-stage diploid and haploid zebrafish embryos, as well as cells from the caudal and pelvic fin, gill, liver, and viscera of adult fish. The haploid embryo-derived cells differentiated in culture to a pigmented phenotype and expressed, upon exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin, a protein that was immunologically and functionally similar to rainbow trout cytochrome P450IA1. Zebrafish cultures were grown in a complex basal nutrient medium supplemented with insulin, trout embryo extract, and low concentrations of trout and fetal bovine serum; they could not be maintained in conventional culture medium containing a high concentration of mammalian serum. Using calcium phosphate-mediated transfection, a plasmid constructed for use in mammalian cells was introduced into zebrafish embryo cell cultures and expressed in a stable manner. These results indicated that the transfection procedures utilized in mammalian systems can also be applied to zebrafish cell cultures, providing a means for in vitro alteration of the genotype and phenotype of the cells.
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A 61-year-old diabetic woman presented with a mycotic aneurysm of the aortic arch, also involving the left subclavian and vertebral arteries, caused by Staphylococcus aureus. Two months before, she had suffered from staphylococcal septic arthritis in her left knee. The patient was treated with antibiotics and an emergency operation was performed involving aneurysm excision and in situ synthetic graft replacement. She died on the fourth postoperative day from hemorrhagic shock.
We describe three cases of extragenital infection by Mycoplasma hominis in three patients transplanted with kidneys from cadaver donors. In two patients, the microorganism was isolated in the exudate from the surgical wound after 72 hrs. of culture on blood-agar (Columbia + 5% horse blood) in CO2 and under anaerobic conditions. In the remaining case, M. hominis was isolated in urine from a suprapubic catheter. All three patients responded satisfactorily to treatment with doxycycline. Mycoplasma hominis should be considered as the possible source of infection in patients at risk because of immunosuppressive therapy and manipulation of the urinary tract. Detection and identification of the organism are difficult without the appropriate techniques.
A retrospective study was undertaken to see if screening ultrasounds and elective surgical revision could decrease access failure. Two hundred fifty-three accesses [177 gortex grafts, 76 arteriovenous (AV) fistulas] were studied with duplex imaging. Patients were subdivided by access type, flow, percent stenosis, and whether they were surgically revised. Data was examined to determine access failure within 6 months. Ten of 76 fistulas clotted (13.1%), while 53 of 177 grafts clotted (29.9%) (p = 0.005). In Gortex grafts, stenosis (p < 0.05) and decreased flow (p = 0.005) correlated with clotting. In unrevised grafts with flow < or = 801 ml/min, 13 of 14 (92.8%) clotted, whereas of those with flow > or = 1603 ml/min only, 10 of 38 (26.3%) clotted (chi-square = 24.74; p < 0.0001). Only 1 of 18 (5.6%) revised grafts with flow < or = 1300 ml/min clotted, while 29 of 69 (42%) unrevised grafts clotted (p = 0.004). We were unable to demonstrate decreased clotting in fistulae with revisions. In conclusion, screening duplex scanning was able to select groups with a higher risk of access failure over the subsequent 6 months. Elective revision with correction of areas of stenosis in grafts with flows < or = 1300 ml/min significantly decreased the incidence of clotting.
Hemodialysis accesses must supply adequate blood flow to perform hemodialysis and maintain access patency. Access flow (QA) is not measured routinely during hemodialysis. The purpose of this study was to evaluate whether access flow changes during hemodialysis and to determine which factors correlate with QA. The authors measured hemodialysis access flow by ultrasound dilution (QA-T) (Transonic HD01 hemodialysis monitor; Transonic Systems, Inc., Ithaca, NY) and duplex ultrasound, with time-domain correlation (QA-S) (Philips CVI Phillips Medical Systems, Santa Ana, CA) hourly, in 19 patients during hemodialysis. Mean arterial pressure (MAP) (Fresenius automated blood pressure cuff) and cardiac output (CO) (Transonic hemodialysis monitor; Transonic Systems, Inc.) also were measured sequentially. Using duplex ultrasound, access flow was unchanged. However, it fell 132 +/- 137 ml/m (p < 0.05) by ultrasound dilution in hr 4. Cardiac output fell 586 +/- 840 ml/ m (p < 0.05), and MAP fell 11.9 +/- 13.0 mmHg (p < 0.01). There were small positive correlations between CO and QA (correlation coefficient (r) = 0.32, QA-T; r = 0.27, QA-S; p < 0.05), and between CO and MAP (r = 0.35; p < 0.01). In conclusion, access flow, CO, and MAP decreased modestly during hemodialysis. Further studies are necessary to see if access flow is similar off dialysis, and whether in-line access flow measurements can decrease access thrombosis.
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Factor XIII a subunit (F13A) is the last enzyme in the blood coagulation cascade. It is characterized by extensive genetic polymorphism defined by 4 common alleles, F13A*1A, 1B, 2A and 2B and a few rare variants, some responsible for severe coagulation deficiencies. In order to infer the evolutionary affinities between the common F13A alleles we have applied PCR techniques to study, in a Northern Portuguese sample, a short tandem repeat polymorphism located within the 5' untranslated region of the F13A gene. The analysis of the molecular heterogeneity within the F13A gene products revealed that the four biochemical variants shared very similar, truncated, distributions of STR alleles and showed no signs of predominant haplotypic associations. These findings seem to support both the inferences that intragenic recombination played an important role in the generation of molecular diversity within each of the four main F13A alleles and that all the four F13A alleles must be rather old. Molecular heterogeneity levels allowed the identification of 1B as the oldest F13A allelic state, and 2A as the most recently generated allele, but were not different enough to accurately track the divergence of alleles 1A and 2B. However, additional analysis of linkage disequilibrium patterns indicates that 1B-->2B-->1A-->2A is the most likely evolutionary order of appearance of F13A main protein alleles, confirming and extending a previous hypothetical model inferred from their molecular features.
BACKGROUND: The extirpation of the sentinel node is a widespread surgical technique whose aim is to avoid axillary resection in patients with breast cancer at early stages. Determination of tumoral infiltration can be evident in the case of macrometastasis (>2mm), or difficult to detect in micrometastasis (<2mm). For this reason we use a protocol of serialized sections, to increase our capacity for detecting micrometastasis. Realisation of this protocol is highly laborious and represents a high cost, thus its effectiveness and efficacy must be studied. MATERIAL AND METHODS: We reviewed 67 sentinel nodes corresponding to 48 patients with breast cancer treated at our hospital in the last three years. All the samples received at the Pathology Unit were included. Serialized sections of three microns were made on each node and with a depth of 40 microns between them. A total of fourteen cuts were made. Every five cuts there was an alternation of immunostaining with a cocktail of queratines (AE1/AE3) and with haemotoxylin-eosin. RESULTS: Sixty-seven sentinel nodes were extirpated from 48 patients. Fourteen positive (20%) were detected. Of these metastases, 6 were macrometastases >2mm, 5 were micrometastases <2mm and 3 were isolated cellular groups (between 0.2 and 2mm). In 6 cases (43%), the metastases only became evident with queratine staining in serialized cuts. Axillary resection was carried out in 44 cases. CONCLUSIONS: The histological study of the sentinel nodes makes it possible to evaluate the status of tumoral infiltration of the axillary ganglions and to greatly reduce axillary lymphadenectomies. The conventional study of the sentinel node (with a single section) is insufficient for the diagnosis of tumoral infiltration. In our series, histological study using a protocol of serialized sections has enabled us to detect some 43% of metastases in the sentinel node that were not evident in the initial section.
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