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Biomedical subjects

P Valente

Publications and source records attributed to P Valente.

13 recordsLinked to original sources
PubMed1991

The complete sequence of perlecan, a basement membrane heparan sulfate proteoglycan, reveals extensive similarity with laminin A chain, low density lipoprotein-receptor, and the neural cell adhesion molecule.

A heparan sulfate proteoglycan is a component of all basement membranes. This molecule consists of three heparan sulfate side chains linked to a large core protein of approximately 400 kDa. We have isolated seven overlapping murine cDNA clones that encode the entire mRNA sequence of 12.685 kilobases of this molecule. This sequence has a single open reading frame of 3,707 amino acids that encodes for a protein of 396 kDa. Identical or near identical matchups with nine peptide sequences derived from the core protein of the molecule isolated from the Engelbreth-Holm-Swarm tumor were found with the deduced sequence. Sequence analysis and data base comparison of the deduced sequence show the protein to consist of five different domains, most of which contain internal repeats. Domain I contains a start methionine followed by a typical signal transfer sequence and a unique segment of 172 amino acids that contains the three probable sites of heparan sulfate attachment, SGD. Domain II contains four cysteine- and acidic amino acid-rich repeats that are very similar to those found in the LDL receptor and proteins such as GP330. Domain III consists of cysteine-rich and globular regions, both of which show similarity to those in the short arm of the laminin A chain. Domain IV contains 14 repeats of the immunoglobulin superfamily that are most highly similar to the immunoglobulin-like repeats in the neural cell adhesion molecule. Domain V contains three repeats with similarity to the laminin A chain G domain that are separated by epidermal growth factor-like regions not found in the laminin A chain. As the primary structural data agree with the appearance of the molecule in the electron microscope as a series of globules separated by rods, or "beads on a string," we have adopted the name perlecan for this molecule. The variety of domains in perlecan suggest multiple interactions with other molecules.

Amino Acid Sequence↗
PubMed1990

Biotinylation of double stranded DNA after transamination.

The bisulfite catalyzed transamination of cytidine and cytosine has been reported to be single strand specific, but local thermal instabilities of the DNA double helix, coupled with the extreme sensitivity of the Biotin-Avidin revelation methods, allows the random labelling of cytosines in d.s. DNA to detectable levels for those purposes where the overall label can be very low. We have evaluated the use of this reaction to prepare double stranded DNA molecules containing N4-aminoethyl-cytosine (4-aeC). After this step 4-aeC residues can be conjugated to biotinyl-n-hydroxysuccinimide ester yielding biotinylated DNA. This reaction allows the massive production of biotinylated probes. Labelled DNA can serve as molecular weight marker and positive control in Southern-blots. Moreover it can be useful in the study of DNA-protein interaction and in the isolation of d.s. DNA-binding proteins through chromatographic procedures.

Amination↗
PubMed1990

Laser assisted fusion of the rat stomach: preliminary studies.

The purpose of this study was (1) to determine whether rat gastrotomies could be securely closed without sutures by CO2 laser-induced tissue fusion alone and (2) to compare some characteristics (physical, biochemical, histological) of laser-fused gastrotomies with sutured gastrotomies. Following pentobarbital anesthesia a 1.5-cm longitudinal anterior gastrotomy was made in the forestomach of male Sprague-Dawley rats. This wound was closed using either a sutureless tissue weld created by a microscope-mounted CO2 laser (153 W/cm2) (Group I, N = 61) or with a running 6-O polypropylene suture (Group II, N = 58). Animals were sacrificed on Postoperative Days 1, 2, 4, 7, and 11 and the wounds were studied. Survival to scheduled sacrifice was 95% in Group I and 93% in Group II. Although bursting pressure of laser-fused gastrotomies was significantly lower than that of sutured controls on Postoperative Day 1, measurement on subsequent days showed comparable wound strength between the laser and suture groups. Wound hydroxyproline content was significantly higher on Postoperative Day 1 and lower on Postoperative Day 11 in the laser group. Histologic examination of the laser-fused wounds revealed less inflammation and earlier reepithelialization than the sutured wounds, giving the microscopic appearance of a "neater" healing wound. These results suggest that laser-induced fusion is a feasible method of gastrointestinal wound closure which may complement standard suture techniques.

Animals↗
PubMed1990

Role of the placenta in perinatal transmission of HIV.

The role of the placental tissue in the perinatal transmission of HIV is still far from being understood. Significant data regarding transplacental infection have been collected, but differences in technique have led to controversy. It appears clear that many Hofbauer cells are CD4+ and can become infected with HIV. Less certain but probable is infection of trophoblasts themselves. Whether infection is CD4 mediated or via cell-cell fusion is not established. Transplacental traffic of virus and cells remains a little-studied possibility. Further data are needed regarding the fascinating concept of the placenta as a modulator of infection.

Female↗
PubMed1989

Carcinogenic risk assessment: some comparisons between risk estimates derived from human and animal data.

Carcinogenic risk assessment may be based on epidemiological as well as experimental data; the aim of the present study is to compare these two procedures and to verify the efficiency of some animal bioassays for the prediction of tumor incidence and relative risk in man. The predictability obtained from animal models has been found to be fairly consistent with the data obtained from epidemiological studies.

Animals↗
PubMed1978

Acute leukopenia associated with silver sulfadiazine therapy.

A patient with a 30% scald burn was treated with topical silver sulfadiazine (Silvadene). On two occasions, within 48 hours of treatment, the patient developed acute leukopenia. Bone marrow aspiration revealed cell maturation arrest. The possible mechanisms of this leukopenia are discussed. It is recommended that daily leukocyte counts be done in burn patients being treated with silver sulfadiazine.

Acute Disease↗