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Biomedical subjects

S Goldenberg

Publications and source records attributed to S Goldenberg.

At least 91 records · Page 5Linked to original sources
PubMed1989

Changes in fatty acid composition associated with differentiation of Trypanosoma cruzi.

The fatty acid composition during the transformation of Trypanosoma cruzi epimastigotes into metacyclic trypomastigotes (metacyclogenesis) was analysed by gas-liquid chromatography and mass spectrometry. Significant qualitative and quantitative changes in the fatty acid composition occurred during incubation of epimastigotes derived from LIT medium in the triatomine artificial urine (TAU). Metacyclogenesis was also followed by alterations in the fatty acid pattern but these were considerably less pronounced when compared to the pattern obtained for TAU-incubated epimastigotes. These results suggest that changes in the lipid composition precede the morphological transformation of epimastigotes into metacyclic trypomastigotes.

Animals↗
PubMed1989

Ciliary ultrastructure of respiratory and fallopian tube epithelium in a sterile woman with Kartagener's syndrome. A quantitative estimation.

Ciliary ultrastructure was studied and quantitatively estimated in a 27-year-old sterile woman suffering from complete KS. Ciliated epithelium was obtained from both nasal mucosa and a fallopian tube. Cilia from both locations were devoid of DA. Various MT abnormalities were found in 16 percent of respiratory epithelial and 21 percent of fallopian tube ciliary cross-sections. The abnormality related to radial spoke defect was frequently seen. The findings in the fallopian tubes were compared to three normal control cases. In these, DA were visible, and MT defects were mainly of excess or missing microtubules. The relevance of these findings to fertility is not clear.

Adult↗
PubMed1989

Light and scanning electron microscopic studies of the effects of CO2 laser on the palatine mucosa of rats.

In order to verify the effects of CO2 laser on the palatine mucosa of rats, 15 animals were utilized. The animals were anaesthetized with thionembutal by intra-peritoneal injection and the palatine mucosa of each animal was irradiated with a single pulse of 10 W. The results showed that immediately after the irradiation of CO2 laser, the formation of small cavities is observed. The wound healing post operationem is gradually in 1 week. The region is totally occupied by neoformed connective tissue and epithelial cells. Numerous polymorphonuclear cells and fibroblasts may be seen between the neoformed collagen fibres.

Animals↗
PubMed1988

Cyclic AMP and adenylate cyclase activators stimulate Trypanosoma cruzi differentiation.

A chemically defined in vitro differentiating condition was used to study the potential role of cyclic AMP (cAMP) and adenylate cyclase activators on the transformation of Trypanosoma cruzi epimastigotes to the infective metacyclic trypomastigotes (metacyclogenesis). It was observed that both addition of cAMP analogs or adenylate cyclase activators to the differentiating medium stimulated the transformation of epimastigotes to metacyclic trypomastigotes. These results were further corroborated by showing that inhibitors of cAMP phosphodiesterase were stimulatory while activators of this enzyme inhibited the metacyclogenesis process. On the other hand, inhibitors of calmodulin inhibited the transformation of epimastigotes to metacyclic trypomastigotes, suggesting that T. cruzi adenylate cyclase might be activated by calmodulin. In addition, the results strongly suggest that guanine nucleotide binding proteins are involved in T. cruzi adenylate cyclase activation. This system may be useful for studying cell differentiation mechanisms in eukaryotes.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

Cell-substrate adhesion during Trypanosoma cruzi differentiation.

The transformation of Trypanosoma cruzi epimastigotes to the mammal infective metacyclic trypomastigotes (metacyclogenesis) can be performed in vitro under chemically defined conditions. Under these conditions, differentiating epimastigotes adhere to a surface before their transformation into metacyclic trypomastigotes. Scanning and transmission electron microscopy of adhered and non-adhered parasites during the metacyclogenesis process show that only epimastigotes and few transition forms are found in the first population, whereas metacyclic trypomastigotes are exclusively found in the cell culture supernatant. PAGE analysis of the [35S]methionine metabolic labeling products of adhered and non-adhered parasites shows that although most of the polypeptides are conserved, adhered parasites express specifically four polypeptides in the range of 45-50 kD with an isoelectric point of 4.8. These proteins might be involved in the adhesion process and are recognized by an antiserum against total adhered parasite proteins. This antiserum also recognized a group of 45-50 kD in the iodine-radiolabeled surface proteins of differentiating cells, providing direct evidence that these components are indeed surface antigens. The results suggest that epimastigotes must adhere to a substrate before their transformation to metacyclic trypomastigotes, being released to the medium as the metacyclogenesis process is accomplished. This could correspond to the process naturally occurring within the triatomine invertebrate host.

Animals↗
PubMed1988

A study on the amphiphilic proteins of three Trypanosoma cruzi populations.

1. Amphiphilic proteins were partially purified from culture-derived metacyclic trypomastigotes of the CL and Colombian strains and of the Dm 28c clone of T. cruzi by the use of Triton X-114. These proteins were subjected to one- and two-dimensional polyacrylamide electrophoresis in the presence of sodium dodecyl sulphate. 2. Relatively simple protein profiles with only 5 to 6 major bands were obtained. The CL and Colombian strains produced at least one additional major protein band (86 kDa) compared to the Dm 28c proteins. 3. Trypomastigote amphiphilic proteins displayed both electrophoretic mobilities and isoelectric points identical to those of two polypeptides precipitated by a rabbit antiserum which recognized metacyclic trypomastigote-specific surface antigens. 4. The partial purification of the T. cruzi amphiphilic proteins with Triton X-114 may provide a simple preparative step for the study of these differentiation-related polypeptides, as well as for the study of strain-specific (glyco)proteins and of their possible biological role.

Animals↗
PubMed1987

Carbonic anhydrase cytochemistry in mitochondria-rich cells of salamander larvae gill epithelium as related to age and H+ and Na+ concentrations.

Carbonic anhydrase (CAH) was localized in the mitochondria-rich cells (MRC) of 1-week-old salamander larvae gill epithelium, in both MRC and pavement cells of 6-week-old larvae, and in regenerated stems of previously amputated gills. CAH activity of the MRC was measured quantitatively using a microscope densitometric technique. Changes in CAH activity per cell and changes in the numbers of CAH-positive MRC were followed under different H+ and Na+ concentrations at the two age groups. CAH activity per cell increased with age, whereas the numbers of CAH-positive MRC dropped. CAH activity per cell in the 1-week-old age group reached maximal values at pH 7.4 and stayed relatively high in the more alkaline media. Moderate increases of Na+ concentrations had small but significant effects on increasing CAH activity of gill MRC. When taking into consideration not only the changes in cellular activity but also the changes in the number of CAH-positive cells under the different acclimation media, an activity index (ICAH) was calculated. Thus, the ICAH in the 1-week-old was found to be dependent on the decline of ambient H+ concentrations (expressed as increasing pH), reaching maximal effect at pH 8.0. On the other hand, raising the Na+ concentrations of the acclimation media to 110 and 220 mOsm/liter caused a maximal inhibition of tissue CAH activity as expressed by ICAH. In conclusion, it is suggested that salamander larvae gill MRC take part in the adaptation of the larvae to changing H+ concentrations of their milieu rather than in their adaptation to changes in its osmolality.

Aging↗
PubMed1985

Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi.

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.

Animals↗
PubMed1985

CO2 laser and suture in splenic parenchyma: an experimental study.

Hemisplenectomy was performed with the scalpel in 12 mongrel dogs. The blood vessels of the splenic pedicle were temporarily clamped. In a six-dog group, hemostasis was obtained by CO2 laser and residual bleeding was controlled by sutures. In the other six dogs, group hemostasis was performed only by sutures. The surgical procedure was free of mortality. No hematological changes were observed in both groups. Histological studies revealed a better hemostatic effect and intensive necrosis of the splenic parenchyma in the lasered group compared with the sutured group.

Animals↗
PubMed1985

In vitro differentiation of Trypanosoma cruzi under chemically defined conditions.

Metacyclic trypomastigotes of Trypanosoma cruzi have been obtained in chemically defined axenic culture. The differentiating medium, composed of artificial triatomine urine supplemented with proline, allows high yields of metacyclic trypomastigotes after 72-h incubation of T. cruzi cells at 27 degrees C. Morphological differentiation of the parasites is gradual under these chemically defined conditions and is preceded by the expression of stage-specific polypeptides. The yield of in vitro-induced metacyclic trypomastigotes depends upon the age of the epimastigote culture, the size of the inoculum and the depth of the medium. Metacyclic trypomastigotes differentiated in vitro from the Dm 28c clone of T. cruzi are both resistant to complement lysis and to macrophage digestion. They are able to infect mice with an efficiency similar to that obtained for natural metacyclic trypomastigotes obtained from triatomine excreta.

Amino Acids↗
PubMed1985

Stage specific gene expression precedes morphological changes during Trypanosoma cruzi metacyclogenesis.

The transformation of epimastigotes to metacyclic trypomastigotes of the Trypanosoma cruzi clone Dm 28c has been studied in an in vitro system consisting of artificial triatomine urine supplemented with newborn calf serum. The comparison of morphological data with gene expression products, as judged by the proteins synthesized during differentiation, has shown that stage specific gene activation precedes by far the morphological changes of differentiating cells. Immunoprecipitation of differentiating cell antigens with a trypomastigote stage specific antiserum has shown that although the morphological differentiation process takes six days to be completed, epimastigotes start to express the Mr 86 000 and the 78 000 trypomastigote antigens within the first 12 h of induction.

Animals↗
PubMed1985

Thinking about the threat of nuclear war: relevance to mental health.

Ontario students in grades 7-13 responded to open-ended and multiple-choice questions about future concerns, particularly unemployment, job/career plans, and the nuclear threat. Although worries about nuclear war were more frequent than those in other areas, their expression was associated with a sense of social efficacy rather than with feelings of helplessness.

Adolescent↗
PubMed1983

The translation of the messenger for the poly(A)-binding protein-associated with translated mRNA is suppressed. A case of cytoplasmic repression in duck erythroblasts.

In vivo protein synthesis in duck erythroblasts was compared to in vitro translation of polyribosomal and free cytoplasmic mRNA. The in vivo study showed the absence of de novo synthesis of the Mr 73 000 poly(A)-binding protein found associated with all polyribosomal mRNA. In vitro translation demonstrated that the mRNA for this protein is absent from the polyribosomal mRNA fraction but constitutes a medium frequency messenger among the repressed free mRNA. This result confirms the existence of a qualitative translational control in terminal differentiating duck erythroblasts leading eventually to the arrest of the protein synthesizing machinery.

Animals↗
PubMed1983

Differential repression of specific mRNA in erythroblast cytoplasm: a possible role for free mRNP proteins.

Two types of in vivo untranslated 'free' mRNA-protein particles (mRNP) were isolated from duck erythroblast cytoplasm and characterised. Both types, namely the highly purified globin mRNA-specific '20S' mRNP and the '35S' mRNP containing a heterogenous non-globin mRNA population, are not translatable in rabbit reticulocyte lysates, but yield active mRNA upon deproteinisation. In vivo, 90% of globin mRNA is translated, but the majority of mRNA types are found in the inactive mRNP fraction, including fully repressed mRNA species. Searching for the factors controlling differential mRNA repression, we characterised and compared the protein composition of globin and '35S' mRNP using two dimensional gel electrophoresis, in vivo labelling with [35S]methionine and in vivo phosphorylation. The major proteins ubiquitously bound to globin or any other mRNA in the polyribosomes (e.g., the 73 K mol. wt. poly(A) binding protein) were not detected in purified inactive mRNP. In the latter some polypeptides appear to be associated with only one of the two inactive mRNA types while some others are common to both mRNPs. Furthermore, different rates of synthesis and phosphorylation characterize the protein populations of the two types of repressed mRNP. The specificity in composition and metabolism of the populations of polypeptides associated with different subpopulations of inactive cytoplasmic mRNA, as shown here, argues in favour of a role of mRNP proteins in mRNA recognition and selective translational repression, possibly in association with the ScRNA previously found as components of the free mRNP and able to inhibit protein synthesis.

Animals↗
PubMed1983

Water balance of five amphibian species at different stages and phases, as affected by hypophysial hormones.

Five amphibian species were studied for the effect of hypophysial hormones on their water balance. The species were three anurans, Rana ridibunda, Bufo viridis and Pelobates syriacus, and two urodeles Salamandra salamandra and Triturus vittatus. In the first four species different stages of development were studied, in the newt both the terrestrial and aquatic phases of the adult were examined. The hormones used were oxytocin (OXY), arginine vasotocin (AVT) and prolactin (PL). Oxytocin caused most water retention when compared with the other hormones, especially responding were juveniles of Rana and Bufo, but also the terrestrial phase of the adult newt Triturus. Arginine vasotocin affected mostly juvenile Pelobates. Prolactin caused water retention in juvenile Rana and in the terrestrial phase of Triturus. In general the hormones affected the juvenile stages more than either larvae or adults.

Amphibians↗