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Biomedical subjects

M Rojas

Publications and source records attributed to M Rojas.

At least 145 records · Page 8Linked to original sources
PubMed1989

Evidence for substantial formation of r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene- deoxyguanosine in human lymphocytes treated in vitro with benzo[a]pyrene.

The possibility that the amounts of r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene- deoxyguanosine (anti-BaP diol epoxide-dGuo) and r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene- deoxyguanosine (syn-BaP diol epoxide-dGuo) may vary in human lymphocyte cultures from different donors was investigated by comparing DNA adducts formed after treatment with [G-3H]benzo[a]-pyrene (4 microM) for 24 h. In most cases, greater than 50% of the DNA adducts were derived from r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (syn-BaP diol epoxide).

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1989

[Mirizzi syndrome: experience of 77 cases].

Mirizzi syndrome is estimated to occur in about 1% of cases requiring urgent or elective biliary tract surgery. The key anatomic finding is extrinsic compression of the common duct by a stone located in the gallbladder or cystic duct. Among patients operated on in the last 12 years we have found 77 patients meeting criteria to diagnose Mirizzi syndrome. 76% were females, usually over 40 years of age; jaundice was present in 98% and elevated alkaline phosphatase in 97% of cases. Percutaneous transhepatic cholangiography allowed the diagnosis in 32 of 41 patients. The most common surgical technique involved a patch repair of the gallbladder over the Kehr tube in 45 patients. Eight patients required biliary-jejunal bypass. Eleven patients were reoperated on for benign stenosis of the biliary tract over a 1 month to 10 year period of follow up.

Adolescent↗
PubMed1989

Hyperthecosis of the ovary. Clinicopathologic study of 19 cases with immunohistochemical analysis of steroidogenic enzymes.

Nineteen cases of ovarian hyperthecosis found in the Surgical Pathology Department files of the George Washington University Medical Center between 1976 and 1988 were reviewed. In all of these cases the ovaries were removed as part of a procedure for another clinical diagnosis. None of the cases was associated with clinical virilization, but the endometrium was abnormal in 15 of the 17 cases in which it was available for examination, ranging from simple hyperplasia to well differentiated adenocarcinoma. Immunohistochemical analysis of the ovarian lesion for cytochromes P-450 17 alpha and P-450AROM, which catalyze androgen and estrogen synthesis, respectively, was performed in nine cases in which adequate tissue was available. P-450 17 alpha was localized in luteinized stromal cells in six of these cases--the endometrium of four of which was carcinomatous--while P-450AROM was not present in any case. These results confirm androgen production by the luteinized stromal cells in hyperthecosis, and suggests that estrogenic effects in these cases are mediated through peripheral aromatization of these androgens.

Adult↗
PubMed1989

Analysis of lectin binding in benign and malignant thyroid nodules.

The lectin binding properties of ten cases each of adenomatoid nodule, follicular adenoma, and papillary carcinoma and five cases of microinvasive follicular carcinoma were examined histochemically and compared with adjacent normal thyroid tissue. Wheat germ agglutinin, concanavalin A, Ulex europaeus agglutinin I, peanut agglutinin, soybean agglutinin, Dolichos biflorus agglutinin, Ricinus communis agglutinin, and Helix pomatia agglutinin were employed. All the lectins but Ulex europaeus agglutinin I, peanut agglutinin, and Helix pomatia agglutinin were bound to thyroid parenchymal cells, colloid and stromal cells, but none uniquely to thyroid parenchymal cells. Helix pomatia agglutinin binding was present in stromal cells but not in parenchymal cells. Ulex europaeus agglutinin I binding to parenchymal cells was weakly positive only in five cases of papillary carcinoma. The binding in adenomatoid and neoplastic cells and their colloid was stronger than in adjacent normal thyroid tissue in all cases examined. Wheat germ agglutinin and concanavalin A binding was most intense among the lectins examined. In papillary carcinoma, lectin binding was observed mostly in the apical cytoplasm of carcinoma cells, whereas a diffuse surface binding pattern was predominant in follicular adenoma and carcinoma, adenomatoid nodules and normal thyroid gland. No consistent differences in lectin binding were found between follicular adenoma and carcinoma, or between adenomatoid nodules and follicular neoplasia.

Adenoma↗
PubMed1988

Differences in the DNA adducts formed in cultured rabbit and rat dermal fibroblasts by benzo(a)pyrene and (-)benzo(a)pyrene-7,8-diol.

Benzo(a)pyrene (BaP) is highly carcinogenic in rats but is without effect in rabbits when administered s.c. The possibility that BaP-DNA adducts could be responsible for this species difference was investigated by comparing BaP-deoxyribonucleoside adducts formed in dermal fibroblast cultures from Wistar rats and New Zealand rabbits. Treatment with [G-3H]BaP (1.2 microM) for 6, 24, and 48 h produced an essentially qualitative species-specific difference. Over 95% of the DNA adducts in the rabbit dermal cell cultures were derived from anti-BaPDE; the major BaP adduct formed (90%) was (+)-anti-BaPDE-deoxyguanosine. This adduct was formed at very low levels in the rat dermal fibroblasts (7%). These cells contained a large proportion of (+/-)-r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene (syn-BaPDE)-DNA adducts (45%) and over 48% of other, unidentified, BaP-DNA adducts. Cells treated with (-)-BaP-7,8-diol (1.2 microM) produced almost exclusively (greater than 99%) (+)-anti-BaPDE-deoxyguanosine in rabbit cells, while the rat cells did not form this product. These results suggest that adducts other than anti-BaPDE-deoxyguanosine may be involved in rat s.c. BaP carcinogenesis; the preferential formation of (+)-anti-BaPDE-deoxyguanosine by rabbit dermal fibroblasts does not directly correlate with the resistance of rabbit dermis to tumor formation.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1988

Comparison of DNA adducts in mouse and rat epidermis versus dermis after topical application of (+/-)r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene and (+/-) benzo(a)pyrene-4,5-oxide.

Mice and rats were treated topically with the BP metabolites, anti-BPDE and BPO. Rat epidermal DNA was extensively modified by BPO, while mouse epidermal DNA was preferentially modified by anti-BPDE. Anti-BPDE-dGuo adducts were observed only in mouse dermal DNA. DNA adducts were absent from the rat dermis. This adduct formation could be the reason for the very different in vivo biological effects of BP metabolites in the two species.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1988

Serological activity against galactosyl-alpha(1-3)galactose in sera from patients with several kinetoplastida infections.

Using rabbit erythrocyte-derived neutral glycosphingolipids enriched for a defined ceramide pentasaccharide as antigens, we have detected elevated anti-galactosyl-alpha(1-3)galactose (anti-G alpha G) antibody values in patients with American cutaneous leishmaniasis (ACL), chronic Chagas' disease, and Trypanosoma rangeli infections compared with normal subjects or with patients suffering from any of 15 other infectious diseases. The specificity of the G alpha G antibodies was determined by inhibition enzyme-linked immunosorbent assays, which revealed that several alpha-galactosyl- but not beta-galactosyl-bearing sugars blocked absorption of G alpha G antibodies to the specific antigen used. G alpha G antibodies were mainly distributed between immunoglobulin classes G and M in three Kinetoplastida infections studied, with a lower increase in reactivity detected in immunoglobulin A. Absorption of highly reactive G alpha G antibodies with purified murine laminin and nidogen, two basement membrane proteins, almost abolished G alpha G reactivity, suggesting the identity of anti-G alpha G with laminin and nidogen antibodies previously reported as elevated in Kinetoplastida infections. In ACL, G alpha G antibodies were detected in 71% of patients having skin lesions with a clinical evolution time of 0.5 month. This percentage increased with the time of evolution of skin lesions, reaching 93% in lesions older than 3 months, and tended to decrease inversely to the induration diameter in the skin leishmanin test. It is proposed that similar epitopes may exist on kinetoplast protozoa and that the determination of G alpha G antibodies may be a highly sensitive assay for the detection of humoral responses to Kinetoplastida infections.

ABO Blood-Group System↗
PubMed1988

Persistence of elevated levels of galactosyl-alpha(1-3)galactose antibodies in sera from patients cured of visceral leishmaniasis.

Using rabbit erythrocyte-derived neutral glycosphingolipids enriched for a ceramide pentasaccharide as the antigen, we detected elevated anti-galactosyl-alpha(1-3)galactose (anti-G alpha G) antibody levels in 76% of children with active visceral leishmaniasis (kala-azar [KA]) and in 42% of clinically cured patients with KA who had been treated about 5 years previously with meglumine antimonate (30 mg/kg in a series of 15 daily injections). The long-term persistence of elevated G alpha G antibodies was also found in 56% of children living in the same geographic zone who, at the time of the initial clinical examination, had fever and evident splenomegaly with hyperglobulinemia but a negative bone marrow aspirate for leishmanial bodies. Five years after antimonate treatment, these clinically cured children with presumptive KA were studied serologically. Their mean G alpha G antibody values were slightly lower than those in patients with active KA but were still abnormal. Using different biochemical and immunological approaches, we found that elevated G alpha G antibodies present in patients with KA bound specifically to glycoconjugates with an alpha(1-3)-terminal galactose residue. G alpha G antibodies were mainly distributed between immunoglobulin classes G and M in patients with active KA and in antimonate-treated patients with clinically cured KA. The possibility of the existence of remnant living parasites or the persistence of inserted G alpha G epitopes in parasitized macrophages was proposed as a mechanism to explain the long-term persistence of abnormal G alpha G antibodies in patients apparently cured of KA.

Acute Disease↗
PubMed1987

Circulating antibodies to mouse laminin in Chagas disease, American cutaneous leishmaniasis, and normal individuals recognize terminal galactosyl(alpha 1-3)-galactose epitopes.

Sera from patients with American cutaneous leishmaniasis and Chagas disease and from monkeys infected with either Trypanosoma cruzi or Trypanosoma rhodesiense show, in RIAs, strong binding to mouse laminin. A distinct although weaker binding activity is also detected in normal human sera. The antibodies recognize a common carbohydrate epitope present on mouse laminin, which was assigned to a terminal galactosyl(alpha 1-3)-galactose group. Distinct crossreactions were observed with some other basement membrane proteins, rabbit glycosphingolipids, defucosylated human B blood group substance and components produced by some human tumor cells. Only little activity was, however, found on laminin obtained from human placenta. The data indicate that the antibodies arising in infectious diseases are stimulated by similar carbohydrate epitopes present on the surface of parasites. Tissue-specific occurrence of such epitopes may exist and explain the involvement of distinct tissues in autoimmune disorders.

Animals↗
PubMed1987

Sulphatide content in a membrane fraction isolated from rabbit gastric mucosal: its possible role in the enzyme involved in H+ pumping.

The sulphatide content of vesicular membrane fraction from rabbit mucosal gastric microsomes was analyzed. This vesicular membrane fraction, in addition to a high sulphatide content, was enriched in an ouabain-insensitive (H+ + K+)-ATPase, a (Mg+2 + K+)-activated phosphatase, and a H+ pumping activity. The enzyme system involved in the process of acid secretion and the translocation of K+ was studied in these membrane preparations treated with arylsulphatase A, an enzyme that specifically hydrolyzes sulphatide. The results indicate that the breakdown of sulphatides of the vesicular membrane fraction inactivated both the (H+ + K+)-ATPase activity and the H+ pumping. Both activities were partially restored by the sole addition of sulphatide. The K+-stimulated ouabain-insensitive phosphatase activity, suggested as a partial reaction of the (H+ + K+)-ATPase sequence, was unaffected by arylsulphatase. These results suggest that sulphatides may play a function in the high activity binding site for K+ of the enzyme involved in H+ pumping.

Adenosine Triphosphatases↗
PubMed1987

Immunocytochemical localization of lingual lipase in serous cells of the developing rat tongue.

The ontogeny of the rat lingual serous and mucous glands was explored by light and electron immune microscopy using the peroxidase-antiperoxidase and streptavidin-gold techniques. Tissues from fetal and neonatal rats from day 18 of gestation through 4 wk after birth were fixed and embedded in paraffin or Epon for light and transmission electron microscopy, respectively. Electron microscopy revealed that the only cells containing lingual lipase were the developing serous cells; secretory granules containing lingual lipase of varying degrees of maturity were seen. Mucous cells did not show immunospecific staining in rats of any age. The neonatal "mixed" lingual glands secrete lingual lipase from serous components immediately after birth to aid in fat digestion.

Animals↗
PubMed1987

Effect of salt depletion on sodium concentration in serum and urine of Bufo chilensis. Evidences for increased levels of neurohypophysial principles in their plasma.

Salt-depleted toads Bufo chilensis were compared with animals maintained in NaCl solution and a control group with respect to Na+ content in serum and urine. Plasma hydro-osmotic activity of the animals was measured by increased water transfer across the isolated urinary bladder of the frog (Caudiverbera caudiverbera). Sodium in serum is not affected by pre-adaptation in distilled water. Urine Na+ is markedly reduced. Plasma from depleted animals increases water transfer across the isolated urinary bladder. Immersion in NaCl solution did not have this effect. An increase in neurohypophysial hormones in the blood of the animals is postulated.

Animals↗
PubMed1987

Polymorphonuclear leukocytes in the endometrium during the normal menstrual cycle.

We investigated the presence of polymorphonuclear leukocytes (PMNs) in normal endometrium. Hematoxylin and eosin stained slides of 100 endometrial curettage and biopsy specimens were reviewed for dating and presence of PMNs. Polymorphonuclear leukocytes were quantitated by chloroacetate esterase (CAE) stains. Polymorphonuclear leukocytes were present in large numbers in areas of tissue degradation (day 28 and menstrual phase endometrium) and were found only in small numbers in intact tissue throughout the cycle. The CAE and H&E stains showed minimal difference in ability to detect PMNs. Polymorphonuclear leukocytes could be easily discriminated from endometrial granulocytes, which did not stain with CAE.

Cell Count↗
PubMed1987

Antibodies to basement membrane proteins nidogen and laminin in sera from streptococcal-related diseases and juvenile rheumatoid arthritis patients.

Using the ELISA technique, antibodies against two different basement proteins, laminin and nidogen (ALNA), were determined in 226 children suffering from one of 37 different inflammatory or infectious diseases. These included 80 patients with streptococcal infection and 40 with juvenile rheumatoid arthritis. Forty-eight percent of the streptococcus-infected patients (or 75% of those in the acute phase) and 60% of juvenile rheumatoid arthritis patients had significantly elevated ALNA levels compared with healthy controls. Interestingly 10 adult rheumatoid arthritis patients displayed normal ALNA levels, suggesting a particular immune process occurring in children affected by juvenile rheumatoid arthritis. By means of periodate oxidation and glycosidase treatments we have shown that ALNA positive sera recognized terminal alpha-galactose as the reactive epitope.

Acute Disease↗
PubMed1987

Incidence of contamination with aflatoxin in precooked corn flour, corn grain and cracked corn.

A study was carried out to determine the presence and content of aflatoxins in 90 samples of precooked corn flour (23 yellow and 67 white), 40 samples of corn grain (30 yellow and 10 white), and 30 samples of yellow cracked corn. No aflatoxin was detected in white corn grain. The other investigated samples showed the following rates of contamination: yellow corn grain, 10%, ranging from less than 5 to greater than 10 ppb; yellow cracked corn, 16.6%, ranging from less than 5 to greater than 20 ppb; and white corn flour, 6%, and yellow corn flour, 87%. Of 14 aflatoxin positive samples tested, only 1 contained more than 20 ppb, the administrative guideline established by the US Food and Drug Administration (FDA). The results of this survey do not appear alarming because of the relatively low incidence and low levels of aflatoxin detected. However, since Venezuela is a big consumer of corn and corn-derived products, a more detailed investigation is suggested to establish the realistic levels of aflatoxin in these commodities.

Aflatoxins↗
PubMed1986

Comparison of benzo[a]pyrene-DNA adduct levels in mouse and rat epidermis and dermis.

Male Swiss mice and Wistar rats were treated topically with 250 nmol/mouse and 750 nmol/rat of [3H]benzo[a]pyrene ([3H]BaP). The initial level of total BaP--DNA and the individual modified deoxyribonucleoside adducts were similar in the skin epidermis of the two species. The concentration of these adducts was approximately 3 times less in both mouse and rat dermis. The decreased amount of BaP bound to DNA of mouse dermis may be related to the resistance of this tissue to the carcinogenic action of BaP. The ability of both the mouse (susceptible) and rat (resistant) skin to form BaP-bound products similar in nature and ratio in the epidermal and dermal DNA, suggests that other mechanisms are involved in the difference in the biological response of epidermis versus dermis to the carcinogenic effect of BaP.

Animals↗
PubMed1986

In vivo formation and persistence of DNA and protein adducts in mouse and rat skin exposed to (+/-)benzo[a]pyrene-4,5-oxide.

The objective of the present study was to compare DNA and protein adduct formation of benzo[a]pyrene-4,5-oxide (BPO) in vivo and to determine the persistence of the adducts in both mouse and rat epidermis. (+/-)BPO at a dose of 100 nmol/mouse and 200 nmol/rat was topically applied to male Swiss mice and Wistar rats. Three hours after application, there was 3-fold less binding of BPO to mouse epidermal DNA than to rat epidermal DNA; inversely, the amount of BPO bound to mouse skin protein was 3.6 times higher than in rat skin protein. One and three weeks after application of BPO, persistence of 17-20% of the initial amount of BPO-DNA adducts and 2-4% of initial amount of BPO bound to protein was detected in both mouse and rat skin epidermis. H.p.l.c. analysis of the enzymatic hydrolysates of DNA from mouse and rat epidermis 3 h after application of BPO showed five distinct products: one early-eluting, two BPO-deoxyguanosine (dGuo) (ratio 1.5:1) and two BPO-deoxyadenosine (dAdo) adducts (ratio 2:1). The ratio of the total modified dGuo to the total modified dAdo was 2:1. The amount of total BPO-dGuo and BPO-dAdo adducts was 3.5 times greater in rat than in mouse epidermis. Persistence of the major BPO-dAdo adduct was observed in mouse and rat epidermal DNA, and 1 and 3 weeks after topical application of BPO there was a 6-fold greater amount of the persisting BPO-dAdo adduct in rat skin epidermis than in mouse skin epidermis (4.1 and 0.66 pmol/mg DNA, respectively). Minor amounts of the BPO-dGuo were found to persist in rat skin epidermis DNA.

Animals↗