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G Perez

Publications and source records attributed to G Perez.

At least 73 records · Page 4Linked to original sources
PubMed1990

Location of the carbohydrates present in the HK-ATPase vesicles isolated from hog gastric mucosa.

The glycosylation of H+K(+)-ATPase vesicles isolated from hog gastric mucosa was investigated by various methods. Following protein separation on sodium dodecyl sulfate reducing gels and transfer to poly(vinyl difluoride) membranes, binding of concanavalin A was confined to the 94-kDa band which corresponds to the catalytic subunit. In contrast, wheat germ agglutinin binding occurred in a region below the 94-kDa subunit, corresponding to the 60-85-kDa region, and also to protein just above the catalytic subunit. Treatment with glycopeptidase F removed most of the concanavalin A staining and also the wheat germ agglutinin staining found below the 94-kDa region, but spared the higher molecular weight wheat germ agglutinin reactive material. During the deglycosylation experiments a protein of 35-kDa was produced. Sequencing analysis of V8 protease generated peptide fragments of the 35-kDa protein show at least 30% homology with the Na+K(+)-ATPase beta-subunits. Labeling of the carbohydrates by galactosyltransferase and [3H]uridine diphosphate-galactose showed that the sites of labeling were extracellular and were confined to the wheat germ agglutinin staining regions. Two molecular weight regions, below the 94-kDa region, of 60 and 85 kDa were identified. Electron microscopy using postembedding staining techniques showed that both concanavalin A and wheat germ agglutinin staining occurred on the extracellular face of the gastric vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1990

Isolation and characterization of a lectin from the seeds of Dioclea lehmanni.

Affinity chromatography of the globulin fraction from the seeds of Dioclea lehmanni on Sephacryl S-200 yielded two lectins, one slightly retarded and another strongly bound. The latter, which was a glucose/mannose specific lectin, was purified and the following properties were determined: pI, Mr of subunits, carbohydrate content, A, aminoacid composition, hemagglutination and inhibition patterns, N-terminal sequence and mitogenic activity. These properties of the lectin were very similar to those of the Con A and Dioclea grandiflora lectins.

Amino Acids↗
PubMed1990

Micronutrient status and human immunodeficiency virus (HIV) infection.

This study surveyed serum concentrations of vitamins, electrolytes, and trace elements in subjects seropositive for HIV-1 by ELISA and confirmatory Western blot. Thirty subjects (26 males, 4 females) were recruited at a hospital clinic. Seventeen were classified as having mild or severe ARC (AIDS-related complex), 7 had AIDS, and 6 were asymptomatic. Eight had experienced weight loss of 10 pounds or more in the past 6 months. Most (93%) were anergic to skin test antigens. Percentages of subjects with below normal plasma concentrations include: zinc-30%, calcium-27%, magnesium-30%, carotenes-31%, total choline-50%, and ascorbate-27%. Eighty-seven percent of the subjects had at least one abnormally low value. Percentages with above normal values include: folate-37% and carnitine-37%. Some subjects with above normal values for plasma vitamins reported self-supplementation, usually with large doses. The results suggest that one or more abnormally low concentrations of the plasma micronutrients studied here are likely to be present in the majority of HIV seropositive patients.

AIDS-Related Complex↗
PubMed1990

Iron chelation by deferoxamine inhibits lipid peroxidation during cardiopulmonary bypass in humans.

Iron catalysis is involved in oxygen-derived free radical generation and subsequent lipid peroxidation, which have been reported to occur during cardiopulmonary bypass in humans. We assessed the effects of the iron chelator deferoxamine on the susceptibility of circulating low density lipoproteins (LDLs) to induced peroxidation in 20 adult patients (10 controls and 10 treated) undergoing cardiopulmonary bypass for coronary or valve procedures. Deferoxamine was given both intravenously (30 mg/kg body wt, starting 30 minutes before bypass and extending for the next 4 hours) and as an additive to the cardioplegic solution (250 mg/l). Blood samples were taken from both atria before and immediately after the end of cardiopulmonary bypass. Plasma lipid peroxidation was assessed by measuring spectrophotometrically the thiobarbituric acid reactive substances (TBARS) content of selectively isolated LDLs after their exposure to a peroxidizing agent. Before cardiopulmonary bypass, the right and left atrial blood values of LDL-TBARS were not significantly different between the two groups. Cardiopulmonary bypass resulted in a lipid peroxidation of significantly greater magnitude in control than in treated patients. Postbypass right atrial values for LDL-TBARS (expressed in mumol/mmol LDL-phospholipids) were 45.7 +/- 17.2 (mean +/- SEM) in control patients and 6.9 +/- 2.9 in treated patients (p less than 0.02), whereas in the left atrial blood, LDL-TBARS yielded values of 62.7 +/- 20.5 and 10.3 +/- 3.9, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗
PubMed1990

HIV-1 and HTLV-I infection in renal transplant recipients.

The prevalence of retroviral infection in renal transplantation remains poorly defined. We tested retrospectively sera from 224 of 331 patients undergoing renal transplantation between 1979 and 1985. Viral antigen based EIA was used for screening IgG antibodies to human immunodeficiency virus (HIV-I) and human T-cell leukemia virus type I (HTLV-I). Positive EIAs were confirmed by Western blot. Six patients (2.7%) were found to have retroviral infection, four with HIV-1 and two with HTLV-I. The four patients with HIV-1 infection were negative before and became EIA and Western blot positive following transplantation. All patients had transient HIV-1 antigenemia documented before antibody was detected. One patient died of Kaposi's sarcoma 2 years posttransplantion with a functioning graft. One is alive and asymptomatic 4 years posttransplant, and two rejected their grafts and are asymptomatic on maintenance hemodialysis. Six patients tested positive for HTLV-I by EIA. Only two patients, however, were also positive for HTLV-I by Western blot, RIPA, and p24 antigen RIA, one prior to and one after transplantation. Both had HTLV-I-positive lymphocyte cultures and remain asymptomatic of retroviral infection 3 years after renal transplantation. A third patient, positive for HTLV-I by EIA, had indeterminate Western blot and negative RIPA, RIA, and lymphocyte culture. Intravenous drug use was not a risk factor for retroviral infection in this patient population. It is likely that patients became infected peritransplantation from blood transfusions. Contamination by donor kidneys, however, cannot be excluded.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Duration of retinogenesis: its relationship to retinal organization in two cricetine rodents.

The Mongolian gerbil (Meriones unguiculatus) has a prolonged period of development relative to other muroid rodents. We have explored the consequences of this relatively long period of maturation on retinal cell number and topography by comparing the duration and topography of neurogenesis in the gerbil retina with that of a closely related species which develops rapidly, the Syrian hamster (Mesocricetus auratus) (Sengelaub et al.: J. Comp. Neurol. 246:527-543, 1986). An analysis of thymidine-labeled retinas indicate that cells destined for the gerbil retinal ganglion cell layer are generated for at least 12 embryonic days, twice the duration in the hamster. The period of cell loss in the gerbil retinal ganglion cell layer extends for at least 14 postnatal days, more than twice as long as in the hamster. The gerbil retina is generated in a center-to-periphery gradient for both retinal ganglion cells and displaced amacrine cells, while no such gradients are evident in the hamster retina. We conclude that the longer developmental period of the gerbil is associated with 1) a longer period of neurogenesis resulting in greater retinal cell number, 2) the expression of spatial gradients in neurogenesis, and 3) a larger eye at maturity. The last two factors, in part, may be related to the development of a highly differentiated area centralis and visual streak in the retina of this rodent. Unrelated to duration of growth, early differences in retinal shape between these two species contributes to the development of retinal topography. The gerbil, but not the hamster retina, is initially asymmetric, longer in its nasotemporal than its dorsoventral dimension. The gerbil retina then grows asymmetrically, producing a spherical retina, and coincident in time, a nasotemporally extended visual streak.

Animals↗
PubMed1989

Human immunodeficiency virus and human T-cell leukemia virus type I in patients undergoing maintenance hemodialysis in Miami.

The high prevalence of human immunodeficiency virus (HIV-1) infection in populations at risk in Miami prompted a seroepidemiologic study of both HIV-1 and the human T-cell leukemia virus type I (HTLV-I), a closely related virus, in our patients receiving chronic hemodialysis. One hundred twenty-nine patients undergoing hemodialysis in 1986 and 1987 were tested for antibody against both viral antigens by EIA (Abbott Laboratories, Abbott Park, IL). Seroreactive samples for HIV-1 and/or HTLV-I were confirmed by Western blot and, for HTLV-I, by viral cultures. Thirty patients (23.2%) were positive for retroviral infection (22 for HIV-1 alone, four for HTLV-I alone, and four for both HIV-1 and HTLV-I). The most important risk factor was intravenous drug use, followed by blood transfusion. Patients with HIV-1 had lower T4-T8 ratios and higher mortality than those with HTLV-I infection alone. It was concluded that HTLV-I, as well as HIV-1, infection is endemic in chronic dialysis centers in Miami. The clinical consequences of HTLV-I infection in relatively immunocompromised patients with chronic uremia who are undergoing chronic hemodialysis remains to be established.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Protection of rhesus monkeys from fatal Lassa fever by vaccination with a recombinant vaccinia virus containing the Lassa virus glycoprotein gene.

Lassa fever is an acute febrile disease of West Africa, where there are as many as 300,000 infections a year and an estimated 3000 deaths. As control of the rodent host is impracticable at present, the best immediate prospect is vaccination. We tested as potential vaccines in rhesus monkeys a closely related virus, Mopeia virus (two monkeys), and a recombinant vaccinia virus containing the Lassa virus glycoprotein gene, V-LSGPC (four monkeys). Two monkeys vaccinated with the New York Board of Health strain of vaccinia virus as controls died after challenge with Lassa virus. The two monkeys vaccinated with Mopeia virus developed antibodies measurable by radioimmunoprecipitation prior to challenge, and they survived challenge by Lassa virus with minimal physical or physiologic disturbances. However, both showed a transient, low-titer Lassa viremia. Two of the four animals vaccinated with V-LSGPC had antibodies to both Lassa glycoproteins, as determined by radioimmunoprecipitation. All four animals survived a challenge of Lassa virus but experienced a transient febrile illness and moderate physiologic changes following challenge. Virus was recoverable from each of these animals, but at low titer and only during a brief period, as observed for the Mopeia-protected animals. We conclude that V-LSGPC can protect rhesus monkeys against death from Lassa fever.

Animals↗
PubMed1989

A plasma inhibitor of platelet aggregation in patients with Lassa fever.

Previous studies have shown that haemorrhage in Lassa fever is associated with abnormal in vitro platelet aggregation and a high mortality. In Sierra Leone we studied platelet aggregation in healthy local subjects, patients with laboratory-confirmed Lassa fever and febrile patients in whom Lassa virus infection was excluded. There were no significant differences in the mean platelet counts of these groups. Patients with fulminant Lassa virus infection showed a gross depression of in-vitro platelet responsiveness to 1 and 5 microM ADP and 4 micrograms/ml collagen compared to other groups (P = 0.0004-0.0008 when compared to healthy controls, P = 0.002-0.0008 when compared to mild Lassa fever patients). When plasma samples from five of these patients were mixed 1:1 with control platelet-rich plasma, a marked inhibition of ADP-induced aggregation was observed. No inhibitory activity was detected in plasma obtained from healthy subjects or febrile control patients. The presence of inhibitor was strongly associated with the occurrence of haemorrhage (P = 0.03), depression of platelet aggregation (P = 0.004) and severity of Lassa fever (P = 0.007).

Adenosine Diphosphate↗
PubMed1989

Brain lesions in patients with acquired immunodeficiency syndrome.

Infections involving the brain have become a major complication in patients with acquired immunodeficiency syndrome. We have reviewed 48 cases of central nervous system lesions in patients with acquired immunodeficiency syndrome. and its related complex. All patients had computed tomographic scans with contrast performed; 31 of 48 were intravenous drug abusers. Computed tomographic abnormalities found included 21 patients with multiple ring-enhancing lesions, 13 with single ring-enhancing lesions, 11 with single hypodense lesions, and three with multiple hypodense lesions. Twenty-five patients had a positive serologic reaction for Toxoplasma. Sixteen patients had brain tissues examined. Of the 16 patients, six had cerebral Toxoplasma (one with concomitant Mycobacterium tuberculosis), and ten had diagnoses other than toxoplasmosis (three of whom had a positive serologic reaction for Toxoplasma). Two patients had M tuberculosis; one patient had Nocardia asteroides with Salmonella enteritidis. Of the remaining seven patients, three had encephalitis of unknown cause, two had inconclusive tissue diagnoses, one had progressive multifocal leukoencephalopathy, and one had vasculitis. In the population of intravenous drug users, brain lesions from diseases other than toxoplasmosis may be just as prevalent. Attempts to obtain a diagnosis from brain tissue is highly recommended to permit the design of effective and specific therapy for those diseases amenable to therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Hepatitis B virus markers and persistent antigenemia in adolescents.

Adolescents attending a municipal outpatient adolescent clinic in New York City were evaluated for the prevalence of hepatitis B virus (HBV) markers and persistent antigenemia. Among 313 teenagers tested in 1 year, 11.8% were HBV marker positive, and 4.8% had persistent antigenemia. Hispanic teens had a marker rate of 6.4% and an antigenemia rate of 1.4%. Dominican Republic teens had a significantly higher marker rate than Puerto Rican teens. Among Hispanics, sexual activity status and foreign- vs. U.S.-born status were not significantly related to the presence of HBV markers. Asian teenagers had a 50% marker rate and a 27.2% rate for persistent antigenemia. Marker and antigenemia rates were highest in the most recent immigrants. Unexplained persistent hematuria occurred more frequently in patients with HBV markers than in patients without markers. We recommend routine hepatitis B surface antigen screening in Hispanic and Asian adolescents. The greatest at-risk groups are Asians, especially recent immigrants, immigrants from the Dominican Republic, and probably patients with unexplained persistent hematuria.

Adolescent↗
PubMed1988

Outcome of patients with human immunodeficiency virus on maintenance hemodialysis.

Fifty-one adults with HIV infection, including 20 chronic hemodialysis patients with superimposed HIV infection and 31 patients with HIV-associated nephropathy requiring chronic maintenance hemodialysis were followed to evaluate survival on outpatient dialysis in relation to the clinical stage of the HIV infection. Regardless of when they contracted the infection, AIDS patients who required maintenance hemodialysis had a poor prognosis. All 17 patients who developed AIDS died after a mean of 93 +/- 32 days on hemodialysis (median 30 days; range 2 to 540 days). On the other hand, 12 asymptomatic HIV carriers were alive after a mean follow-up on chronic hemodialysis of 488 +/- 75 days (median 420 days; range 142 to 850 days); and five hemodialyzed patients with ARC were alive after 564 +/- 191 days (median 420 days; range 150 to 1230 days). The data confirm the lack of effectiveness of maintenance hemodialysis for prolonging life in patients with AIDS. This dismal prognosis was evident whether renal failure antedated HIV infection or whether it was HIV-associated. In asymptomatic HIV carriers and in patients with ARC, however, maintenance hemodialysis provides meaningful, long-term life support.

AIDS-Related Complex↗
PubMed1988

Viral hepatitis. The alphabet game.

Differential diagnosis of viral hepatitis begins with a check for darkened urine and bile in the urine. These hallmarks of conjugated hyperbilirubinemia immediately rule out prehepatic liver disease. Next, studies are done for the elevated transaminase levels that are characteristic of hepatitis infection, and a thorough history is taken to rule out drug- and toxin-induced hepatitis that may mimic acute viral hepatitis. Elevated alkaline phosphatase is a good marker of cholestasis. Ultrasonography can clarify this diagnosis. The classic presenting symptoms of viral hepatitis are jaundice, nausea, vomiting, malaise, anorexia, and dull right upper quadrant pain. However, serologic studies are needed to detect the presence of specific viral agents.

Acute Disease↗
PubMed1987

Influence of family planning counseling in an adolescent clinic on sexual activity and contraceptive use.

We evaluated whether family planning counseling (FPC) in an adolescent clinic promoted the onset of sexual activity among the non-sexually active teens and/or increased contraceptive use among the sexually active teens. The FPC focused on the teens' establishing sexual values, the right to say "no," abstinence and alternate forms of intimacy, consequences of intercourse, and the various contraceptive methods. Data for one year were collected on the adolescents' first and subsequent visits to a medically oriented, municipal outpatient adolescent clinic. There were 383 teenagers who qualified for the study. Of these, 35% (134) reported premarital sexual activity. During the study period, 3% (8) of the 249 nonsexually active teens reported becoming sexually active. Among the 134 sexually active teens at clinic entry, 27% reported using a contraceptive method at their most recent sexual encounter. Among the 142 sexually active adolescents at the conclusion of the study, 76% reported contraceptive use at their most recent sexual encounter (p less than 0.001). We conclude that the provision of FPC to nonsexually active and sexually active teens does not appear to promote the onset of sexual activity significantly among the non-sexually active group, although it significantly increases contraceptive use among the sexually active group.

Adolescent↗
PubMed1987

Relationship between hepatic levels of glutathione and sulphobromophthalein retention in hyperthyroidism.

1. Sulphobromophthalein (BSP) retention and liver glutathione levels were studied in uncomplicated hyperthyroid patients. 2. BSP retention was increased in 52.5% of the subjects at admission (n = 40) and in 28% of the cases after 3 months of propylthiouracil treatment (300-400 mg/day) (n = 25). 3. Hepatic levels of glutathione were measured in six patients and significant inversed power correlation with BSP retention was observed (r = 0.968, P less than 0.001). 4. These data support the contention that the alteration of the BSP retention observed in hyperthyroidism could be due to a decreased availability of hepatic glutathione for conjugation.

Adolescent↗