Search PubMed⌕ Search

Biomedical subjects

E Lopez

Publications and source records attributed to E Lopez.

At least 109 records · Page 6Linked to original sources
PubMed1984

[Are Stannius corpuscles the parathyroid glands of teleost fishes? Ultrastructural, cytologic and immunocytochemical arguments].

Parathyrin of Stannius corpuscles (PCS), glands which are restricted to Holostei and Teleostei, is closely related to mammalian parathyrin (PTH) secreted by the parathyroids [( 6] to [9]). In unstimulated and stimulated CS we have shown the same structure and cellular types that are described in mammalian parathyroids. We observed three types of cells; the two sorts of cells already described [14] present such a difference of density (Fig. 1) that type I may be compared to chief dark cells and type II to chief light cells. The difference between these two forms was particularly marked in activated CS; a similar observation has been reported concerning PT [15]. Furthermore, we have detected a third type of cell present either singly in unactivated CS or in small groups between chief cells in activated CS. They showed all the characteristics of oxyphil cells [17]; they present an extremely dense cytoplasm with numerous mitochondria and a typical stellate form with cytoplasmic processes extending between chief cells (Figs. 2, 3). In CS of untreated eels, we have shown by means of indirect immunocytology (using an immunserum raised against the active fragment 1-34 bPTH) that the immunostained reaction product was limited to dilated cisternae and ribosomes of the rough endoplasmic reticulum and to most of the granules in all the chief cells (Figs. 4, 5). No immunoreaction was observed in Golgi area. Oxyphil cells did not present an immune localization of PCS. CS are structurally and cytologically similar to mammalian PT; furthermore their chief cells synthesize, stock and secrete a substance immunologically similar to mammalian PTH; the exact function of oxyphil cells has to be demonstrated.

Animals↗
PubMed1984

Goldfarb and Mathews: legal challenges to the dependency test for spouse's benefits.

Changes in the eligibility criteria for a survivor's benefit under the Social Security program resulted from a 1977 Supreme Court decision in the case of Califano v. Goldfarb. The Court ruled that legislation that required only men to prove past financial dependence on a deceased spouse in order to establish eligibility to a survivor's benefit violated equal protection guarantees in the Constitution. In a 5-4 decision, the majority of the Supreme Court Justices determined the constitutionality of the gender-based distinction by applying the heightened scrutiny test. For a statutory gender-based classification to be found constitutional under the test, the government must show that (1) use of a gender-based classification serves an important governmental purpose and (2) a direct and substantial relationship exists between the gender-based classification and the purported objective. The majority of the Court found the sex-based distinction was based on sexist assumptions about women, was not formulated to serve an important governmental objective, and, thus, was unconstitutional. Amid projections that elimination of the dependency test for men would increase annual Social Security benefit expenditures by as much as +500 million, Congress enacted a government pension offset provision to help minimize the cost increase. It required that any spouse or survivor who received or was eligible to receive a pension for his or her own work in noncovered public employment would have his or her Social Security surviving spouse's or dependent's benefit reduced dollar-for-dollar by the amount of the work-related pension. An exception clause was included in that legislation.(ABSTRACT TRUNCATED AT 250 WORDS)

Eligibility Determination↗
PubMed1984

Factors influencing postoperative survival in aortic regurgitation. Analysis by Cox regression model.

From 1965 to 1981, 114 patients underwent aortic valve replacement for severe aortic regurgitation in our institution. Catheterization was performed preoperatively in 103 patients. Follow-up was possible in 98% of the survivors. Long-term survival was significantly different between patients in preoperative Functional Class I-II and those in Class III-IV (p less than 0.03); those with a preoperative cardiothoracic ratio less than 0.64 versus greater than or equal to 0.64 (p less than 0.001); and those with a preoperative ejection fraction greater than 0.50 versus less than or equal to 0.50 (p less than 0.03). A multifactorial analysis was used to identify the dominant preoperative prognostic variables affecting survival. Three of the 13 parameters examined simultaneously were found to independently influence survival rates: cardiothoracic ratio (p = 0.001), strain pattern on the electrocardiogram (p = 0.072), and left ventricular end-systolic pressure (p = 0.127). After stratification of the population into two groups according to preoperative functional class, the predictive variables were cardiothoracic ratio (p = 0.014), strain pattern (p = 0.050), and acute/chronic form of aortic regurgitation (p = 0.034). This statistical analysis enabled us to derive a mathematical equation for predicting an individual patient's probability of survival. We found a close fit between the survival rate predicted by the mathematical model and the observed survival rate.

Adolescent↗
PubMed1983

Microcomputer-controlled plotting of environmental health data.

A general microcomputer program has been developed which facilitates the preparation of finished plots of geographical and temporal variations in such data as: the concentrations of suspended airborne particulate matter and of metallic and organic components detected in the particulate; the incidences of several kinds of respiratory illnesses and symptoms; epidemiological information obtained from physicians, hospitals, pharmacies, and schools. Examples of plots produced by the program, detailed explanations of how it works and a complete program listing are included.

Air Pollutants↗
PubMed1983

T cell regeneration after allogeneic bone marrow transplantation.

Various T cell subsets were characterized by double immunofluorescent staining using monoclonal antibodies (MoAb) in blood, bone marrow (BM) and tissues of 29 patients after allogeneic BM transplantation (BMT). In an attempt to prevent graft versus host disease (GvHD), 15 patients received cyclosporin A (Cy A). In the remaining 14 patients the BM was pre-incubated with a MoAb, OKT3. The regeneration of T4+ subset was delayed and the level of T8+ cells was abnormally high even 1 year after engraftment. This did not have any predictive value for the appearance of complications such as GvHD or severe viral infections. The number of T8+ cells was lower in the group of patients who received Cy A than in the OKT3 group (0.7 +/- 0.2 vs 1.5 +/- 0.3 X 10(9)/1 at day 90). In contrast to normal individuals, the T4/T8 ratio in both blood and regenerating BM of BMT patients was less than 1. A sizeable subset of circulating T cells expressed the phenotype T8+, T10+, HNK-1+, DR+. Circulating cells of this phenotype were transiently very high (up to 50%) in patients with active GvHD or suffering from severe viral infection. This subpopulation of lymphocytes was not found in the epidermal infiltrate that accompanied GvHD where the predominant phenotype was T8+, T1-, T10-, HNK-1-, DR-. We conclude therefore that after BMT the number and phenotype of circulating T cells reflects the T cell distribution seen in the regenerating BM.

Adolescent↗
PubMed1983

[Comparative effects of an extract of Anguilla Stannius corpuscles and of an active fragment of human parathyroid hormone (1-34 hPTH) on an anuran batracian, Xenopus laevis].

Parathyrin of the corpuscles of Stannius (PCS), glands which are restricted to Holostei and Teleostei, resembles mammalian parathyroid hormone secreted by the parathyroids. These glands made their first phylogenic appearance with Amphibians, whereas the Stannius corpuscles disappeared. We have compared, in the clawed toad, Xenopus laevis, the effects of injections of extracts of corpuscles of Stannius and of the active synthetic fragment of parathyrin (1-34 hPTH). Both hormones elicited hypocalcemia and hypophosphatemia within a 4 days treatment. These results are interpreted according to the hypothesis that in the most primitive Amphibians there are receptors leading to hypocalcemic effect co-existing with the appearance of "new" glands which secrete a hypercalcemic hormone in mammals.

Anguilla↗
PubMed1983

Purchasing power of U.S. Social Security benefits abroad, 1970-82.

This article examines whether the small number of Social Security beneficiaries living abroad enjoy a higher standard of living than they would with the same benefits if they lived in the United States. The article addresses this question using two methods. First, absolute comparisons of U.S. dollar purchasing power abroad are made using "purchasing power parities," a method recently developed to allow international comparisons of real standards of living. Second, the effects of changes in Social Security benefit levels, exchange rates, and rates of inflation on the relative value of benefits abroad are measured. Both methods show considerable instability in purchasing power of Social Security benefits in the 1970's. Although beneficiaries in 1970 generally could live better abroad than in the United States, this advantage eroded considerably during the 1970's, followed by some improvement in 1981-82.

Economics↗
PubMed1982

Effects of membrane composition and lipid structure on the photopolymerization of lipid diacetylenes in bilayer membranes.

Molecules analogous to biological and synthetic lipids have been prepared conjugated diacetylene moieties in the long alkyl chain. These lipid diacetylenes form bilayer structures when suspended in aqueous buffers. Ultraviolet light (254 nm) exposure initiates the polymerization of the diacetylenes in the lipid bilayer to give a fully conjugated, highly colored product. The reaction is topotactic, and its efficiency depends on the correct alignment of the monomeric units. Thus, the lipid diacetylenes are photopolymerizable if the hydrocarbon chains are in a regular lattice found at temperatures below the lipid transition temperature; polymerization is inhibited above this transition. The photopolymerization of a diacetylenic glycerophosphocholine in lipid bilayer membranes was observed in two-component mixtures with a nonpolymerizable lipid, either dioleoylphosphatidylcholine or distearoylphosphatidylcholine. The photochemical and thermochemical characteristics suggest that the diacetylenic glycerophosphocholine exists largely in separate domains in the mixed bilayers. Lipid diacetylenes analogous to a dialkyldimethylammonium salt and to a dialkyl phosphate have a plane of symmetry, which suggests that both chains penetrate equally into the bilayer. The photopolymerization of these symmetrical synthetic species is more than 10(3)-times more efficient than that of the diacetylenic glycerophosphocholine. These differences are interpretable in terms of the expected conformational preference of the lipid molecules.

Alkynes↗
PubMed1981

[Immunocytochemical detection in Stannius corpuscles of the eel (Anguilla anguilla L.) of a hormone similar to the mammalian parathyroid hormone].

In eels the parathyrin of the corpuscles of Stannius (PCS), mammalian parathyroid-like hormone, has been localized in the cytoplasm of all the cells in the corpuscles. This detection was done by indirect immunofluorescence with an antiserum anti 1-84 bovine parathormone. The specificity of the reaction was demonstrated by inhibition of the coloration obtained with the 1-84 bovine parathormone and the active fragment 1-34 of human parathormone. Variations of the cellular localization of the PCS or a complete depletion of the hormonal content were observed in eels made hypercalcaemic by calcium overloading.

Anguilla↗
PubMed1980

[Structural similarities between the hypocalcemia hormone of the corpuscles of Stannius of the eel (Anguilla anguilla L.) and the mammalian parathyroid hormone].

Extracts of the corpuscules of Stannius enhance Eel gill calcium efflux and increase bone resorption in the Rat. Thus the hormone is hypocalcaemic in the Eel although hypercalcaemic in the Rat. We show here that a 15 min. pulse perfusion of a synthetic fragment of human PTH 1-34 had a similar effect on gill calcium fluxes to that of CS extract. Further, we found that Eel plasma contains a substance reacting with five different antibodies against bovine PTH. The concentration of this plasma material is enhanced seven-fold by parenteral calcium and rendered extremely low or absent by CS removal. A convenient name for this major calcium-regulating hormone is parathyrine of the corpuscles of Stannius (PCS) since this reflects both its glandular source and chemical structure.

Anguilla↗
PubMed1980

Paradoxical effect of 1,25 dihydroxycholecalciferol on osteoblastic and osteoclastic activity in the skeleton of the eel Anguilla anguilla L.

Female mature eels (300 to 500 g) received one intraperitoneal injection of 1.25(OH)2D3 (10 microgram). Their vertebral bone was compared, 8 h and 24 h after the injection, with vertebral bone of control mature female eels receiving solvent alone (ethanol). Sexual maturation in female eels induces a bone decalcification with hypercalcaemia and hyperphosphataemia. The control eels showed marked osteoclastic resorption and osteocytic osteolysis and the degree of mineralization of the intercellular substance decreased. Injection of 1.25 (OH)2D3 into these female mature eels provoked as early as 8 h: 1) an increase in hypercalcaemia and hyperphosphataemia; 2) a major conversion of lining cells to osteoblasts and a stimulation of osteoblastic activity with new bone formation; 3) diminished osteoclastic resorption without changing osteocytic osteolysis or bone matrix mineralization.

Anguilla↗
PubMed1979

In vitro sulfate turnover in osteogenesis imperfecta congenita and tarda.

Sulfate (35SO4(-2)) uptake was studied in confluent skin fibroblasts from three patients with osteogenesis imperfecta "congenita," six patients with osteogenesis imperfecta "tarda," three clinically unaffected relatives of an osteogenesis imperfecta tarda patient, and four controls. Only two of the osteogenesis imperfecta congenita cell strains showed an increased uptake of sulfate, all other cell strains being comparable to the control group. The degradation rate of glycosaminolgycans in mutants as seen by the chase experimentas was comparable to that found in the normal control cell strains. Glucose oxidation was normal in the osteogenesis imperfecta cell strains having an abnormal sulfate uptake. This rules out the possibility of an hypermetabolic state of these cells. These findings do not warrant the use of 35SO4(-2) incorporation in cultured cells as a tool for prenatal diagnosis of osteogenesis imperfecta.

Cells, Cultured↗
PubMed1977

[Morphological, cytological, and biochemical changes of Anguilla anguilla L. gills deprived of Stannius corpuscles (S. C.) (author's transl)].

In the silver female eel (Anguilla anguilla L.) maintained in fresh water, surgical removal of Stannius corpuscles (SC) resulted in: a) A significant increase of wet weight of gill cells and the dry weight of gill filaments expressed as function of body weight. b) A proliferation and a hypertrophy of chloride cells shown by a significant rise of cell volume expressed as a precentage of the epithelial volume. c) An increase of the calcium (Ca) binding protein activity in the total branchial mucosa. These modifications are not observed when eels are maintained in Ca-free water. The results are discussed in relation to the Ca fluxes across gills in eels deprived of SC and gill morphological changes during sea water adaptation.

Animals↗