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Biomedical subjects

C Perez

Publications and source records attributed to C Perez.

At least 19 recordsLinked to original sources
PubMed1992

Differential expression within a three-gene subfamily encoding a plasma membrane H(+)-ATPase in Nicotiana plumbaginifolia.

Genomic and cDNA clones for the three members of a gene subfamily (pma) encoding a plasma membrane H(+)-translocating ATPase in Nicotiana plumbaginifolia were isolated and sequenced. They are between 95 and 96% identical at the deduced amino acid sequence level. Sequence comparisons with the corresponding tomato genes (Ewing, N.N., Wimmers, L.E., Meyer, D.J., Chetelat, R.T., and Bennett, A.B. (1990) Plant Physiol. 94, 1874-1881) indicate that divergence among the three N. plumbaginifolia pma genes occurred before the development of the Solanaceae family. Here, determination of pma1 transcription initiation sites reveals several 5' boundaries located 266 to 120 nucleotides upstream from the plasma membrane H(+)-ATPase translation initiation codon. The 5'-untranslated region contains a small open reading frame, 9 residues long. pma3 has a single, 264-nucleotide long 5' leader containing a 5-residue open reading frame. The latter is completely conserved in a corresponding tomato gene. These features suggest the possibility of translational regulation of plant pma genes. S1 nuclease protection assays on total cellular RNA isolated from different organs reveals that all three genes are expressed in leaf, stem, flower, and root tissues, albeit at different levels according to the organ and gene. The different genes for the plant H(+)-translocating ATPase are thus subject to differential regulation of transcription, possibly related to specific aspects of enzyme function.

Amino Acid Sequence↗
PubMed1992

Production of antimicrobials by Bacillus subtilis MIR 15.

We report the isolation and characterization of a strain of Bacillus, designed MIR 15, which appears to produce and excrete antimicrobials active against Gram-negative bacteria, but not against fungi. B. subtilis MIR 15 varied its antimicrobial profiles and production with the cultivation temperature.

Anti-Bacterial Agents↗
PubMed1992

Inhibition of the transepithelial potential difference and short circuit current in the isolated frog skin by alloxan.

1. Electrical parameters: short circuit current (SCC), transepithelial potential difference (PD) and electrical resistance (R) were measured in isolated frog skin (Rana pipiens) in the presence and in the absence of alloxan. 2. Alloxan decreased SCC and PD in a concentration-dependent pattern, while R remained unchanged. 3. The effect on SCC and PD was observed after 25 min of exposure to the drug. Maximal average effect was 20% in SCC and 17.5% in PD. 4. These results suggest that alloxan decreased epithelial sodium transport, through interference with the activity of the Na(+)-K(+)-ATPase.

Alloxan↗
PubMed1992

Surgical treatment of tumors of the distal rectum with sphincter preservation.

One hundred one patients with villous adenoma or invasive carcinoma of the distal rectum treated with local excision or coloanal anastomosis were studied. Twenty-three (45%) of the 51 patients with villous adenomas had transanal excision, another 23 (45%) had a posterior proctotomy, and five (10%) had a coloanal anastomosis. Only two patients with a villous adenoma developed a recurrence requiring repeat local excision. Fifteen (30%) of the 50 patients with invasive cancer were treated by transanal excision. All had tumors confined to the submucosa or superficial muscularis. Eighteen (85%) of 21 patients having posterior proctotomy also had tumors with similar depth of invasion. Six (43%) of the 14 patients having coloanal anastomosis had Dukes' B tumors, six (43%) were Dukes' C, and another two (14%) underwent palliative resection. The overall actuarial 5-year survival was 77%. Only four patients treated by transanal excision or posterior proctotomy died of metastatic disease. In the coloanal group, two of 12 patients undergoing curative resection died of recurrent cancer, and another has a pelvic recurrence. Villous adenomas of the distal rectum and selected carcinomas may be treated with local excision and coloanal anastomosis with preservation of sphincter function with good results.

Adenocarcinoma↗
PubMed1992

Immunodetection of acrosin during the acrosome reaction of hamster, guinea-pig and human spermatozoa.

Mammalian sperm acrosomes contain a trypsin-like protease called acrosin which causes limited and specific hydrolysis of the extracellular matrix of the mammalian egg, the zona pellucida. Acrosin was localized on hamster, guinea-pig and human sperm using monoclonal and polyclonal antibodies to human acrosin labelled with colloidal gold. This was visualized directly with transmission electron microscopy, and with light and scanning microscopy after silver enhancement of the colloidal gold probe. Four distinct labelling patterns were found during capacitation and the acrosome reaction in hamster and guinea-pig spermatozoa, and three patterns were found in human spermatozoa. In the hamster, acrosin was not detected on the inner acrosomal surface after the completion of the acrosome reaction, thus correlating with the observation that hamster spermatozoa lose the ability to penetrate the zona after the acrosome reaction. With guinea-pig and human spermatozoa, acrosin was still detected after the completion of the acrosome reaction, thus correlating with the observation that acrosome reacted guinea-pig spermatozoa bind to and penetrate the zona pellucida.

Acrosin↗
PubMed1991

Regulation of glucose transport in Clone 9 cells by thyroid hormone.

Triiodothyronine (T3) is found to stimulate cytochalasin B-inhibitable glucose transport in Clone 9 cells, a 'non-transformed' rat liver cell line. After an initial lag period of more than 3 h, glucose transport rate is significantly increased at 6 h and reaches more than 3-times the control rate at 24 h. The enhancement of glucose transport by T3 is due to an increase in transport Vmax and occurs in the absence of a change in either the Km for glucose transport (approximately 3 mM) or the Ki for inhibition of transport by cytochalasin B ((1-2).10(-7) M). Consistent with the observed Ki for cytochalasin B, Northern blot analysis of RNA from control and T3-treated cells employing cDNA probes encoding GTs of the human erythrocyte/rat brain/HepG2 cell transporter (GLUT-1), rat muscle/fat cell transporter (GLUT-4), and rat liver transporter (GLUT-2) types indicates expression of only the GLUT-1 mRNA isoform in these cells. The abundance of GLUT-1 mRNA increases approx. 1.9-fold after 24 h of T3 treatment and is accompanied by an approx. 1.3-fold increase in the abundance of GLUT-1 in whole-cell extracts as demonstrated by Western blot analysis employing a polyclonal antibody directed against the 13 amino acid C-terminal peptide of GLUT-1. The more than 3-fold stimulation of glucose transport at 24 h substantially exceeds the fractional increment in transporter abundance suggesting that, in addition to increasing total GLUT-1 abundance, exposure to T3 may result in a translocation of transporters to the plasma membrane or an activation of pre-existing membrane transporter sites.

3-O-Methylglucose↗
PubMed1991

Localization of microfilaments and a tubulin-like protein in crustacean (Rhynchocinetes typus) spermatozoon.

Sperm from the decapod crustacean Rhynchocinetes typus undergo dramatic shape changes as they pass from the vas deferens to seawater and interact with the oocyte envelopes. Using FITC-phalloidin and antitubulin antibodies, we were able to localize microfilaments and a tubulin-like protein in R. typus spermatozoon. Microfilaments and the tubulin-like protein were associated with the sperm rays and spines, but were absent at the spike and at its base. Folded and unfolded spermatozoa display similar fluorescence patterns. SDS-PAGE of whole spermatozoa and electrotransfer to nitrocellulose confirmed the presence of actin and two proteins at 97 kd and 120 kd that bind to tubulin antibodies (tubulin-like proteins). These results demonstrate the presence of actin, but not tubulin, and localize microfilaments in these sperm. It is proposed that this cytoskeletal component is active in sperm during crustacean fertilization.

Actin Cytoskeleton↗
PubMed1991

Comparison of the amino acid sequences of the lectins from seeds of Dioclea lehmanni and Canavalia maritima.

The amino acid sequences of the major lectins from the seeds of Dioclea lehmanni and Canavalia maritima were determined by DABITC/PITC microsequence analysis of peptides derived from the proteins by enzymatic digestions with trypsin, chymotrypsin and the protease from S. aureus V8. These sequences were found to be very similar to those of the lectins from Dioclea grandiflora and Canavalia ensiformis (Con A). The D. lehmanni lectin was unusual amongst legume lectins in that it contained a single Cys.

Amino Acid Sequence↗
PubMed1991

Induction of Na(+)-K(+)-ATPase subunit mRNAs by cycloheximide in a rat liver cell line.

Exposure of confluent Clone 9 cells to 40 microM cycloheximide (CHX), a concentration sufficient to inhibit leucine incorporation by 95% within 5 min, coordinately increased the abundances of Na(+)-K(+)-ATPase subunit mRNAs, mRNA alpha 1 and mRNA beta 1. The CHX-induced increases in mRNA alpha 1 and mRNA beta 1 abundances were, respectively, 1.8- and 1.9-fold at 40 min and 3.0- and 3.3-fold at 6 h. Augmented subunit mRNA contents were also observed after exposure to other protein synthesis inhibitors including 100 microM anisomycin and 100 microM emetine. Upon removal of CHX, the rate of leucine incorporation returned to control values within 1 h, but mRNA alpha 1 and mRNA beta 1 content decreased only slowly and were still elevated at 24 h at 1.7- and 1.8-fold the respective control values. Despite the persistence of increased levels of the subunit mRNAs and normalization of the rate of leucine incorporation, Na(+)-K(+)-ATPase activity was unchanged at 3, 6, 24, and 48 h after removal of CHX. In cells "depleted" of protein kinase C (PKC) activity after a 24-h preincubation in the presence of 160 nM 12-O-tetradecanoylphorbol-13-acetate (TPA), mRNA alpha 1 and mRNA beta 1 abundances were still inducible by CHX. It is concluded that exposure of Clone 9 cells to CHX and other inhibitors of protein synthesis results in increased abundances of Na(+)-K(+)-ATPase subunit mRNAs independently of PKC activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Biopsies of non-small cell lung cancer: central review in cooperative studies of the Radiation Therapy Oncology Group.

Cooperative trials involving many institutions have long been recognized as a major means of gaining enough experience in a reasonably short period of time to determine the effectiveness of new approaches in cancer therapy. In order to make such multiinstitutional trials meaningful, it is necessary to have uniform and objective diagnostic standards in histopathology. Large cooperative therapeutic trials, such as the Radiation Therapy Oncology Group (RTOG) constructs, must rely on the histopathologic diagnoses of many pathologists from varied institutions or subject them to central review, which is a longer and costlier process. This study is an assay of the need for central review in cooperative studies on non-small cell lung cancer, which includes squamous cell, large cell, adenocarcinomas, and combined squamous cell and adenocarcinomas.

Adenoma↗
PubMed1990

A nonsecretable cell surface mutant of tumor necrosis factor (TNF) kills by cell-to-cell contact.

In addition to the induction of tumor regression, tumor necrosis factor (TNF) has been implicated as the causative agent in a number of pathologies, including cachexia, septic shock, rheumatoid arthritis, autoimmunity, and induction of HIV expression. We propose that this complex physiology might be manifest by different forms of TNF: the 17 kd secretory component, the 26 kd transmembrane form, or both. To determine whether the 26 kd form of TNF was biologically active and whether its biology differed from that of the secretory component, we generated uncleavable and solely secretable mutants of TNF and studied their biological activities. We found that an uncleavable mutant of the 26 kd cell surface transmembrane form of TNF kills tumor cells and virus-infected cells by cell-to-cell contact, and that TNF need not be internalized by its target to kill. Thus, the 26 kd integral transmembrane form of TNF may function in vivo to kill tumor cells and other targets locally in contrast to the systemic bioactivity of the secretory component.

Amino Acid Sequence↗
PubMed1990

Developmental changes in sugar and starch taste preferences in young rats.

Recent studies indicate that neonatal and adult rats are attracted to the taste of sugar as well as to starch-derived polysaccharides (e.g., Polycose). The present study investigated whether the relative preference for sweet and starchy tastes changes during the postweaning to adulthood period in male and female rats. This was accomplished by giving growing rats 24-hr/day one-solution (sucrose or Polycose vs. water) and two-solution (sucrose vs. Polycose) preference tests over a 9-week period (from 28 to 98 days of age). Acceptance (absolute intake) of sucrose and Polycose was also evaluated by comparing solution intakes during one-solution tests with water baseline intakes. Dilute solutions were used to minimize postingestive caloric and/or colligative effects. When tested with 2% saccharide solutions, the rats strongly preferred sucrose to Polycose with the preference increasing in magnitude from weeks 1 to 9 of testing. Sucrose acceptance also increased, relative to that of Polycose, after the third test week. When tested with 0.06 molar solutions, the rats initially consumed more Polycose (week 1) but by the fifth test week their sucrose preference and acceptance exceeded that of Polycose. These results indicate that the preference for sweet taste, relative to that for starchy taste, increases with age. Contrary to previous findings, the sweet taste preference was somewhat stronger in the male rats than in the female rats.

Aging↗
PubMed1990

Bacteremias caused by Selenomonas artemidis and Selenomonas infelix.

We report two different cases of bacteremia caused by two recently described Selenomonas species, Selenomonas artemidis and Selenomonas infelix. Both species are normally found in human buccal flora. S. artemidis bacteremia appeared in a patient (number 1) who presented with an air-fluid pulmonary cavity and clinical conditions consistent with an anaerobic lung abscess. While the patient improved with antibiotic therapy, cultures of respiratory secretions yielded Mycobacterium tuberculosis. This case demonstrated a strong possibility of a coexisting lung abscess due to S. artemidis. S. infelix bacteremia appeared in a cancer patient (number 2) with heart disease during preterminal acute respiratory distress. It was more difficult in this case to assess the clinical impact of the Selenomonas organisms on the patient.

Adenocarcinoma↗