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S Goldenberg

Publications and source records attributed to S Goldenberg.

At least 37 records · Page 2Linked to original sources
PubMed1998

Representation of differential expression: a new approach to study differential gene expression in trypanosomatids.

During the past five years, several methods have been described that allow the isolation and cloning of stage-specific or cell-specific genes. The characterization of genes expressed at different stages of parasite development is of the utmost importance for the understanding of the mechanisms involved in the regulation of gene expression. Here, Samuel Goldenberg and Marco Aurelio Krieger describe a method for the amplification and cloning of Trypanosoma cruzi genes expressed specifically at different times of the metacyclogenesis process. This method, representation of differential expression (RDE), should be useful for the isolation and cloning of any trypanosomatid gene transcribing differentially expressed messenger RNA.

Journal Article↗
PubMed1998

Long-term symptom patterns, endoscopic findings, and gastric histology in Helicobacter pylori-infected and -uninfected patients.

There is a paucity of data on the long-term behavior of dyspepsia, endoscopic findings, and gastroduodenal histology in patients with or without Helicobacter pylori colonization. We evaluated these parameters during a period of 7 to 19 years (average, 12.3 years) by baseline and follow-up studies. In 36 patients studied, the pattern of gastroduodenal dyspepsia and esophagogastroduodenoscopy findings remained essentially unchanged in 67% and 56% respectively. Dyspepsia patterns did not correlate significantly with either endoscopic or histologic findings, including the severity or location of gastritis in the fundus or antrum, or the presence or absence of H. pylori gastritis. Of 36 patients with adequate biopsies of the fundus and antrum, H. pylori colonization with gastritis was present in 73% but not in 27%. Progression to various degrees of atrophic gastritis was noted in 100% with, and in none without, H. pylori gastritis. In the fundus, atrophy progressed from 14% to 56%, but intestinal metaplasia did not change. In the antrum, atrophy increased from 22% to 64% and intestinal metaplasia increased from 17% to 36%. No patient demonstrated dysplasia, but severe atrophy was seen in the fundus (6%) and antrum (11%). Only two patients (5%) had severe loss of glandular elements and very low pepsinogen I, and thus can be considered to have developed advanced gastric atrophy.

Adult↗
PubMed1998

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Argentina↗
PubMed1997

Homologues of the 24-kDa flagellar Ca(2+)-binding protein gene of Trypanosoma cruzi are present in other members of the Trypanosomatidae family.

A full-length cDNA encoding the 24-kDa flagellar Ca(2+)-binding protein (FCaBP) of the Dm28c clone of Trypanosoma cruzi was cloned and characterized. Comparison of the deduced amino acid sequence with those of the FCaBPs of other T. cruzi strains revealed greater than 97% sequence conservation. FCaBP-like genes are found in Trypanosoma conorhini, Trypanosoma freitasi, Trypanosoma lewisi, Herpetomonas megaseliae, Leptomonas seymouri, and Phytomonas serpens, but not in Crithidia deanei, Leishmania amazonensis, or Endotrypanum schaudinni: Among various T. cruzi strains, FCaBP genes are located on chromosomes of different size, although all strains possess multiple FCaBP genes organized as tandemly arranged gene families. Northern and Western blot analyses revealed that FCaBP mRNAs are produced in all organisms possessing FCaBP-hybridizing sequences, indicating that expression of FCaBP or an FCaBP-like protein is common to a number of trypanosomatid species.

Animals↗
PubMed1997

Prognostic significance of argyrophilic nucleolar organizer region (AgNOR) in resected non-small cell lung cancer (NSCLC).

The expression of the nucleolar organizer regions (NORs) was quantified in paraffin sections of tumors and lymph node metastasis, by means of digital image analysis, in 75 patients with resected non-small cell lung cancer (NSCLC). Patients were divided in two groups: early stage (stages I and II) and advanced stage (stages IIIa, IIIb and IV). The prognostic significance of AgNOR expression was tested by Cox regression analysis in models controlled for age, sex, vital status, stage and histological type. Tumors at early stages had a lower expression of AgNOR than those at more advanced diseases. The mean values obtained for NORs in advanced disease were almost the same as those in the primary tumors when compared with the corresponding lymph node metastasis (r = 0.90; p < 0.01; linear regression). The prognostic role of AgNOR was significant only for tumors at stages I and II and not for advanced neoplasms (stages IIIa, IIIb and IV). These results encourage the inclusion of AgNOR quantitation in routine material, especially in early lung cancer.

Adult↗
PubMed1996

Heterogeneity of metalloprotease expression in Trypanosoma cruzi.

Expression of metalloprotease activities during metacyclogenesis of a series of strains and clones of Trypanosoma cruzi was investigated using SDS-polyacrylamide gel electrophoresis with a range of different co-polymerized proteolytic substrates. A complex pattern of metalloprotease expression, with considerable quantitative and qualitative variability between strains and life-cycle stages, was apparent. This is in contrast to previously published data, and data presented in this study, which demonstrate a high degree of conservation of expression of cysteine proteases in different strains and clones of T. cruzi. All the metalloprotease activities identified partitioned into the detergent phase of a Triton X-114 extract, suggesting that they are membrane-bound. Developmental regulation of expression during metacyclogenesis, either in terms of quantity, or in terms of difference in relative amounts of different isoforms, was apparent for all isolates studied except CL14. However, a clearly metacyclic-specific/metacyclic-enriched metalloprotease was detected only in T. cruzi Dm28c and 383, and our results demonstrate that a metacyclic-specific metalloprotease common to all isolates of the parasite could not be detected, at least at this level of analysis.

Animals↗
PubMed1996

Light and electron microscopic identification of Cyclospora species in the small intestine. Evidence of the presence of asexual life cycle in human host.

This is the first case of cyclosporiasis in which the parasite was clearly demonstrated in a duodenal biopsy by light microscopy. Electron microscopy identified the stages of sporozoite, trophozoite, schizont, and merozoite. Although only asexual forms were identified in our case, the sexual cycle must have taken place in the human host, because oocysts were detected in stools of the patients. Therefore, it appears that Cyclospora species require only a single host to complete its entire life cycle. Despite the heavy infection, only enterocytes were invaded. The lamina propria and submucosa were not involved. The morphology of Cyclospora in the intestine is similar to that of Isospora, but differs from that of Cryptosporidium. The morphology of the oocyst of Cyclospora resembles that of Cryptosporidium, but differs from that of Isospora. Thus, a combined study of both stool and intestinal biopsy should readily distinguish Cyclospora from Cryptosporidium and Isospora.

AIDS-Related Opportunistic Infections↗
PubMed1996

MDR1/P-glycoprotein function. I. Effect of hypotonicity and inhibitors on rhodamine 123 exclusion.

The MDR1 protein (P-glycoprotein) is a membrane ATPase whose expression results in resistance to several anti-tumor drugs. It has been proposed that the MDR1 protein, in addition to its pumplike properties, can function as (Gill et al. Cell 71: 23-32, 1992; Altenberg et al. Cancer Res. 54:618-622, 1994) or mediate the activity of (Hardy et al. EMBO J. 14: 68-75, 1995) a hypotonic stress-induced Cl- current. In addition, one study found that drug transport and Cl- channel-associated functions of MRD1 were separable and mutually exclusive and that, when cells were swelled, the MDR1 protein could not transport substrate. This hypothesis was tested in four pairs of isogenic cell lines with MDR1 transfectants expression 8,000-55,000 MDR1 antibody binding sites per cell. Cytoplasmic exclusion of rhodamine 123 was used as an indicator of MDR1 function to measure the effect of hypotonic stress, MDR1 inhibitors, and Cl- channel blockers on MRD1 transport function. It was found that MDR1 activity and its inhibition by cyclosporine A or flufenamic acid were unaffected by hypotonicity alone or in combination with Cl- channel blockers.

3T3 Cells↗
PubMed1996

Structural requirements for activity of propafenone-type modulators in P-glycoprotein-mediated multidrug resistance.

The sodium channel blocker propafenone and a series of analogs have been identified as effective modulators of P-glyco-protein-mediated multidrug resistance in human tumor cells. A series of closely related structural homologues showed a highly significant correlation between lipophilicity and pharmacological effect. Reduction of the carbonyl group as well as conversion to a methylether led to a remarkable decrease in activity, whereby lipophilicity lost its predictive character as the main determinant for modulator potency. Similarly, the relative positioning of the acyl- and propanolamine side chains also influences activity, so the distance between carbonyl group and nitrogen atom seems important.

ATP Binding Cassette Transporter, Subfamily B, Mem↗