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Biomedical subjects

M Vasquez

Publications and source records attributed to M Vasquez.

At least 37 records · Page 2Linked to original sources
PubMed1993

Spontaneous development of a chromosomal translocation 5;14 in an Epstein-Barr-virus-associated B-cell lymphoma in a SCID mouse.

C.B-17 SCID mice were inoculated with human peripheral blood leukocytes (PBLs) from normal Epstein-Barr virus (EBV)-seropositive and -seronegative donors. Confirmation of a functioning human immune response was demonstrated by the detection of human antibody after inoculation with rotavirus, tetanus toxoid, or EBV. One group of animals inoculated with PBLs from an EBV-seropositive donor developed immunoblastic lymphomas approximately 9 weeks after transplantation. Confirmation of the species and sex of origin of the tumor cells was established using a spontaneous cell line prepared from the tumor. At passage I, the tumor-cell line (AGTI) showed 15% of the metaphases with a translocation involving chromosomes 5 and 14. A lymphoblastoid cell line (AGLCL) established from the same PBLs from the same donor at the time of inoculation of the mice had a normal female karyotype. The AGLCL and a clone of AGTI cells were analyzed for rearrangement of immunoglobulin heavy chain (IgH) genes; both cell lines showed rearrangement of both IgH alleles. The results outlined in this report suggest that a spontaneous chromosomal translocation involving chromosome 14 occurred in normal PBLs in the SCID mouse.

Animals↗
PubMed1993

Genetically engineered deglycosylation of the variable domain increases the affinity of an anti-CD33 monoclonal antibody.

M195 is a murine monoclonal antibody that binds to the CD33 antigen and is being tested for the treatment of myeloid leukemia. Surprisingly, a complementarity determining region (CDR)-grafted, humanized M195 antibody displayed a several-fold higher binding affinity for the CD33 antigen than the original murine antibody. Here we show that the increase in binding affinity resulted from eliminating an N-linked glycosylation site at residue 73 in the heavy chain variable region in the course of humanization. Re-introducing the glycosylation site in the humanized antibody reduces its binding affinity to that of the murine antibody, while removing the glycosylation site from the murine M195 variable domain increases its affinity. The removal of variable region carbohydrates may provide a method for increasing the affinity of certain monoclonal antibodies with diagnostic and therapeutic potential.

Amino Acid Sequence↗
PubMed1993

Neutralizing monoclonal antibodies that distinguish three antigenic sites on human cytomegalovirus glycoprotein H have conformationally distinct binding sites.

Seven neutralizing murine monoclonal antibodies specific for the glycoprotein H of human cytomegalovirus were produced and used to construct a topological map of two nonoverlapping antigenic sites that are bridged by a third antigenic site. Neutralization assays with 15 laboratory or clinical human cytomegalovirus strains indicated that the monoclonal antibodies recognize three antigenically variable and three conserved epitopes within the three antigenic sites. The variable-domain genes encoding monoclonal antibodies representing each of the three antigenic sites were cloned and sequenced, and molecular models of their binding sites were generated. Conformational differences in the antibody-binding sites suggested a structural basis for experimentally observed differences in gH epitope recognition.

Amino Acid Sequence↗
PubMed1993

Dear Hillary.

Michael Vasquez, president of Health Care Expert Systems, Inc., attended a meeting the task force on healthcare reform. After the meeting, he sent the following letter to Hillary Rodham Clinton, to members of Iowa's Congressional delegation and to Steven Schroeder, M.D., of the Robert Wood Johnson Foundation, who moderated the discussion along with Clinton and HHS Secretary Donna Shalala. Vasquez said he was "concerned that the role of information systems was not adequately represented as part of the possible solution during the discussion."

Efficiency↗
PubMed1992

Hereditary factor VII deficiency in pregnancy: peripartum treatment with factor VII concentrate.

This report describes pregnant sisters with severe factor VII deficiency and peripartum management with factor VII concentrate. In this family, two affected members had previously developed severe postpartum hemorrhage when managed with fresh frozen plasma. Therapy-related complications owing to plasma infusion included viral disease transmission and pulmonary edema. Therefore, to lessen the risks of complications, specific factor therapy was initiated shortly before parturition in both patients. Factor VII concentrate was administered prior to delivery and every 6 hr for the next 72 hr to keep trough levels at approximately 10%. Based on peak and trough levels, the mean factor VII half-lives were determined to be 3.6 and 5.7 hr. Use of the concentrate was associated with uncomplicated delivery and minimal postpartum bleeding.

Factor VII↗
PubMed1992

Respiratory syncytial virus detection by dot blot hybridization with a nonradioactive synthetic oligo deoxynucleotide probe.

A synthetic oligodeoxynucleotide corresponding to a region of the nucleocapside gene (N) of respiratory syncytial virus (RSV), was used as a DNA probe to develop a nonradioactive hybridization assay for the detection of RSV. The probe was labeled by incorporation of biotin-7-dATP to the 3' end by a reaction catalyzed by terminal deoxynucleotydil transferase. The dot blot hybridization assay was found to be specific for RSV when tested against RSV isolates (subgroups A and B) obtained from cell cultures and isolates of adenovirus, reovirus, rotavirus, and pararotavirus. The assay detected both RSV subgroups (A and B) without significant differences. The dot blot hybridization assay using the nonradioactive probe led to similar results to indirect immunofluorescence (IFI) when tested against a panel of 64 clinical samples from nasopharyngeal secretions of infants with clinical symptoms of respiratory disease. This assay may provide the basis for a rapid, simple, and inexpensive method for routine RSV diagnosis.

Base Sequence↗
PubMed1991

Conserved amino acid sequences among plant proteins sorted to protein bodies and plant vacuoles. Can they play a role in protein sorting?

Amino acid sequence comparisons were made between the soybean alpha subunit of beta-conglycinin and 34 members of different plant protein families targeted to seed protein bodies or vacuoles. A number of short conserved amino acid sequences were identified in seed storage proteins, plant protease inhibitors and lectins, and the probable functions of these sequences are discussed. For proteins of known tertiary structure, these sequences map to the surface of the respective molecules. It is postulated that these regions produce a common secondary structure which could interact with other molecules involved in the sorting process. One of these regions, region A, is similar to the yeast carboxypeptidase Y (CPY) vacuolar targeting signal, and is present in both storage proteins and lectins. Computer modeling based upon the tertiary structure of concanavalin A (ConA) was used to generate models representing the structure of two highly related lectins from Dolichos biflorus, one of which is targeted to protein bodies and the other secreted. A different glycosylation pattern together with amino acid sequences upstream of the identified conserved amino acid sequences are predicted to modulate the presentation of the sorting domains in the lectins and be the determinant in the sorting of these lectins.

Amino Acid Sequence↗
PubMed1991

Evidence of infection with organisms producing Shiga-like toxins in household contacts of children with the hemolytic uremic syndrome.

We conducted a prospective study in 87 household contacts of 51 children with hemolytic uremic syndrome to determine the frequency of infection with Shiga-like toxin-producing bacteria. Gastrointestinal tract symptoms occurred in only 1 of 87 contacts. Free fecal toxin was detected in 25 of 64 (39%) of the household members. Neutralization with specific antisera to Shiga-like toxins I and II (SLT-I, SLT-II) revealed that in 6 of these household contacts only SLT-I was present in stool, in 10 only SLT-II was present and in 9 both toxins were found. Thirty-three percent of the hemolytic uremic syndrome families in which 2 or more members were studied had more than 1 household member with free fecal toxin in stool. None of the household contacts was found to have E. coli O157:H7 in feces. Serum samples were available in 77 household contacts; 75% (58 of 77) had serum neutralizing titers of greater than or equal to 1:4 to 1 or both toxins. In those contacts for whom paired sera were available, seroconversion was found in 10 of 24 (42%). These data show that household contacts of children with hemolytic uremic syndrome are commonly colonized with Shiga-like toxin-producing E. coli and seroconversion to Shiga-like toxins occurs frequently in family members of children with hemolytic uremic syndrome.

Adult↗
PubMed1991

Acute renal failure associated with the use of intraperitoneal carboplatin: a report of two cases and review of the literature.

Carboplatin, a new analogue of cisplatin used in the treatment of ovarian carcinoma, has been demonstrated to be less nephrotoxic than its predecessor. To date, hundreds of cycles of therapy have been given without a significant incidence of renal failure. We report herein two cases of acute, nonoliguric renal failure in patients receiving intraperitoneal (IP) carboplatin as chemotherapy for advanced ovarian carcinoma. Each patient had received extensive previous treatment with cisplatin. The baseline serum creatinine levels in the patients were 0.9 and 1.1 mg/dL, respectively. After four cycles of IP carboplatin in Patient 1 and five cycles of IP carboplatin in Patient 2, the serum creatinine levels abruptly rose to 9.0 and 9.5 mg/dL, respectively, within a week after administration of therapy. No other primary etiologies for acute renal failure could be identified in either patient. One patient required hemodialysis briefly. Renal biopsy specimens were obtained from both patients. Patient 1 had focal and moderate interstitial nephritis with mild periglomerular fibrosis. Patient 2 had an edematous interstitium with a diffuse mononuclear cell infiltrate, focal interstitial hemorrhage, and toxic changes in proximal and distal tubules on electron microscopy. Treatment with oral prednisone at 1 mg/kg/day with a rapid taper over 4 weeks was done in both cases with the serum creatinine levels eventually dropping to 4.6 and 2.0 mg/dL, respectively. Acute interstitial nephritis and renal failure to this extent have not been previously reported with carboplatin therapy. The literature regarding carboplatin is reviewed with respect to the pathophysiology of its nephrotoxicity.

Acute Kidney Injury↗
PubMed1990

Effects of spaceflight on the spermatogonial population of rat seminiferous epithelium.

Testes from rats flown on Cosmos 1887 were compared with vivarium control and synchronous control samples. The mean weights of flight testes, normalized for weight per 100 g, were 6.4% less when compared with the vivarium controls. Counts of spermatogonia from tissue sections (seminiferous tubules in maturation stage 6) from five animals in each group revealed 4% fewer spermatogonia in flight testes compared with synchronous controls and 11% fewer spermatogonia in flight samples compared with vivarium controls.

Animals↗
PubMed1989

Hemolytic uremic syndrome and diarrhea in Argentine children: the role of Shiga-like toxins.

Shiga-like toxin-producing Escherichia coli have been associated with hemorrhagic colitis and the hemolytic uremic syndrome (HUS). Because Argentina has the highest reported frequency of HUS in the world, Argentine children were prospectively studied during the HUS seasons for evidence of Shiga-like toxin-related diseases. On the basis of serology, fecal cytotoxin neutralization, stool cultures, and DNA hybridization of colony lysates, most children with HUS had evidence of infection with Shiga-like toxin-producing organisms. Children with spring-summer diarrhea also commonly (32%, confidence interval 18%-46%) had clear-cut evidence of such infection. No controls (children without gastrointestinal, renal, or hemolytic disease) had free fecal cytotoxin, positive cultures for E. coli O157:H7, or DNA probe-positive organisms; 20% of them had low serum titers of antibodies to Shiga-like toxins. E. coli O157:H7 was not common in either HUS or diarrhea patients. The high frequency of Shiga-like toxin-induced diarrhea in young children in Argentina probably explains the high incidence of HUS in this country and suggests that HUS is a relatively uncommon complication of Shiga-like toxin-related disease.

Argentina↗
PubMed1989

Photointeraction of benzophenone triplet with lysozyme.

The quenching of the benzophenone triplet by lysozyme and its constituent amino acids in aqueous solutions have been studied. Native lysozyme quenches the benzophenone triplet with a high rate constant, 4 x 10(9) M-1 s-1. The quenching process takes place with production of significant amounts of free ketyl radicals, phi ketyl = 0.56, but with a very low benzophenone consumption yield (0.022). The consumption yield is considerably smaller than that observed for the free amino acids. This difference can be explained in terms of a dominant back hydrogen transfer to the protein in the disproportionation of the free radicals produced. Reduced and carboxymethylated lysozyme shows a higher quenching rate (7.8 x 10(9) M-1 s-1) and a larger benzophenone consumption yield (0.07). The deactivation of the benzophenone triplet by the native protein leads to its inactivation, with a quantum yield of 0.01. Tryptophan and arginine residues are destroyed with a quantum yield of 0.01. In the modified enzyme tyrosine and methionine groups are also consumed.

Amino Acids↗
PubMed1983

Amyloidosis complicating cystic fibrosis.

A 33-year-old white man with cystic fibrosis and severe chronic pulmonary disease developed nephrotic syndrome and was found to have secondary systemic amyloidosis. Only four such cases have been reported in the English literature. Previously reported cases are reviewed and compared. It is suggested that with increasing longevity in cystic fibrosis, more amyloidosis may be seen.

Adult↗
PubMed1981

Renal papillary necrosis in thyroid carcinoma.

A thirty-four-year-old man with progressive visual impairment was found to have thyromegaly and renal insufficiency at the time of admission. Subsequent evaluation demonstrated bilateral optic neuritis and a thyroid nodule which proved to be a follicular carcinoma. Nephrologic studies revealed bilateral papillary necrosis and chronic interstitial nephritis on biopsy. The patient's renal function stabilized and twenty-four-hour protein excretion diminished after hemithyroidectomy. Carcinoma-related protein production may have played a role in the development of the observed renal lesions. Carcinoma should be a consideration in patients with unexplained papillary necrosis.

Adenocarcinoma↗