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Biomedical subjects

D A Chamone

Publications and source records attributed to D A Chamone.

At least 55 records · Page 3Linked to original sources
PubMed1979

Stimulation of prostacyclin release from vessel wall by Bay g 6575, an antithrombotic compound.

Ingestion of 1.2 g Bay g 6575 daily for 1 week by six healthy volunteers had no effect on blood-coagulation, fibrinolysis, or platelet aggregation in vitro, but it seemed to inhibit platelet aggregation in vivo (shown by a smaller reduction in the platelet aggregate ratio after venous occlusion). Plasma drawn from five volunteers after ingestion of a single dose of 1.2 g of the drug stimulated prostacyclin release from slices of rat aorta which had been washed until they stopped releasing anti-aggregating substances, whereas plasma from the same individuals before ingestion of the substance did not. Administration of either Bay g 6575 or dipyridamole alone had no effect on platelet aggregation in vitro, but combined administration resulted in a striking and prolonged inhibition of A.D.P.-induced platelet aggregation. It is proposed that the previously described antithrombotic properties of Bay g 6575 in animals are due to stimulation of prostacyclin release from the vessel wall, and that this effect is also demonstrable in man.

Adenosine Diphosphate↗
PubMed1978

Turnover of radiolabelled plasminogen and prothrombin in cirrhosis of the liver.

The turnover of purified radiolabelled plasminogen was studied in four patients with cirrhosis of the liver, and that of radiolabelled prothrombin in six patients with cirrhosis of the liver. The cirrhotic patients showed an increased fractional catabolic rate and a decreased synthetic rate, resulting in subnormal plasma levels of plasminogen and prothrombin. The plasma concentration of the two proteins correlated with the synthetic rate, but not with the fractional catabolic rate. Heparin infusion prolonged the shortened half-life of plasminogen in two cirrhotics from 1.25 to 2.10 days and from 1.45 to 1.90 days, and the half-life of prothrombin in three cirrhotics from 2.25 to 2.70 days, from 2.35 to 2.80 days and from 2.40 to 3.70 days. These results indicate that the abnormal turnover of labelled plasminogen and prothrombin in cirrhosis of the liver is due to two mechanisms; increased breakdown, reversible by heparin administration, and impaired synthesis. The decreased plasma levels are, however, mainly caused by decreased synthesis.

Humans↗
PubMedDate not supplied

The role of the fibrinolytic system in thromboembolism.

The present concept of physiologic fibrinolysis was reviewed. It was concluded that the nonspecific proteolytic activity of plasmin would essentially be limited to fibrin in vivo in view of (A) the specific adsorption of activator and of plasminogen onto the fibrin surface resulting in local generation of plasmin and (B) the fact that plasmin, adsorbed to fibrin (in contrast to plasmin in the fluid phase) largely escapes from the action of antiplasmin. The hemostatic balance in the resting condition was discussed. It was concluded that under normal conditions, systemic intravascular fibrin deposition or formation must be either nonexistent or extremely limited. On the other hand, there is considerable evidence that a limited systemic fibrinogenolysis is going on in healthy individuals and that this process can be accelerated by simple physiologic procedures, such as strenuous physical exercise.

Antifibrinolytic Agents↗
PubMedDate not supplied

Cytomegalovirus and other herpesviruses infections in heart and bone marrow transplant recipients.

From January 1988 to January 1989 all the heart transplant and bone marrow recipients at the Instituto do Coração of the Hospital das Clínicas of the University of São Paulo Medical School were studied for the incidence and morbidity associated with herpesviruses infections after transplantation. Five bone marrow and 5 heart transplant recipients were followed for a mean of 4.2 months post-transplantation. All the patients were seropositive for cytomegalovirus (CMV) before admission and 80% experienced one or more recurrences during the observation period. Of the 12 episodes of CMV infection, that were identified in this study, 83% were accompanied by clinical or laboratory abnormalities. However, there was only one case of severe disease. The overall incidence of infection for herpes simplex (HSV) was 50%. Although most of HSV reactivations were oral or genital, one case of HSV hepatitis occurred. One of the 6 episodes of HSV infections that were treated with acyclovir showed an unsatisfactory response and was successfully managed with ganciclovir. All the individuals had anti-varicella zoster virus antibodies, but none of them developed infection. The study emphasizes the importance of active diagnostic surveillance of herpesvirus infections in transplant patients. Both CMV and HSV reactivations showed high incidence and important morbidity and thus, deserve prophylactic therapy.

Adolescent↗
PubMedDate not supplied

Detection of hepatitis B virus DNA by the polymerase chain reaction in anti-HBe positive chronic hepatitis B patients.

Detection of HBV-DNA by PCR was compared with other serological markers (HBsAG, HBeAg and anti-HBe) in a series of 49 Chronic Hepatitis B patients, including 12 with a spontaneous clearance of HBsAg. None of these HBsAg negative cases were PCR positive, but 33/37 (89.2%) HBsAg positive cases were PCR positive (p < 0.0001). Among HBsAg positive samples, nine cases were HBeAg positive and anti-HBe negative, all of them PCR positive. Other 3 patients were HBeAg and anti-HBe positive and these cases were also found PCR positive. A third group included 21 patients anti-HBe positive and HBeAg negative: 19 of them were PCR positive and 2 were PCR negative. The last 4 cases were HBeAg and anti-HBe negative, two of them were PCR positive. The detection of anti-HBe viremic cases in the present series suggest that preC variants could occur in our country. In conclusion, the integrated phase of chronic hepatitis B seems to be less frequent than it was assumed, when only HBeAg or dot blot hybridization techniques were used. The new term "low replication phase" might favorably replace the former "integrated phase".

Base Sequence↗
PubMedDate not supplied

Significance of isolated hepatitis B core antibody in blood donors from São Paulo.

The clinical significance of isolated anti-HBc is still a challenge. To elucidate the real importance of this finding in our blood donors, an investigation algorithm was tested. One hundred and twelve isolated anti-HBc seropositive blood donors underwent clinical evaluation and retesting of HBV markers. Those who presented repeatedly reactive isolated anti-HBc, received a single dose of hepatitis B recombinant vaccine to verify anti-HBs early response. A HBV-DNA determination by PCR was done for those who did not test positive to anti-HBs after vaccine. The level of anti-HBc was recorded as a ratio of the sample-to-cut-off values (S:C ratio) in 57 candidates at donation. Comparing true and false-positive anti-HBc results, the different S:C ratios of them were statistically significant and when less than 2, implying in a false-positive result probability over 80%. A high percent of false-positive results (16.07%) was verified after anti-HBc retesting. HBV immunity was characterized in 49.11%, either by anti-HBs detection in retesting (15.18%), or after a single dose HBV vaccination (33.93%). HBV-DNA was negative in all tested donors. In conclusion, this algorithm was useful to clarify the meaning of isolated anti-HBc in most of our blood donors.

Adult↗
PubMedDate not supplied

[Control of blood transfusion malaria in an endemic and in a non-endemic region in Brazil].

The aim of the present work was to establish appropriate criteria for screening of donor blood from regions with distinct Malaria epidemiological characteristics. Three locations with different screening criteria were studied: São Paulo, SP (with no vectorial transmission), Belém, PA (with low active transmission) and Matupá and Peixoto de Azevedo, MT (with high active transmission). The Malaria parasite--Plasmodium sp--was searched for by "thick film", QBC Test and antigen Immunofluorescence test, and was not detected in any of the samples. There was, however, a great variation in the positivity of anti-plasmodial antibodies, as determined by IIF-IgG anti-P. vivax and -P. falciparum, between accepted donors in the 3 studied locations and between rejected and accepted donors in São Paulo (1.98% accepted, 22.3% rejected--p < 0.01) and Belém (17.2% accepted, 58.3% rejected--p < 0.01). These data endorse the use of the applied clinical and epidemiological screening. In Matupá and Peixoto de Azevedo, where there was no rejected donor, the serological positivity was 80.6%. We, therefore, consider that the Malaria screening in blood banks should follow clinical and epidemiological criteria suitable to each region. The laboratorial screening techniques should then detect either the parasites (thick film/QBC Test or the parasite antigens.

Blood Donors↗
PubMedDate not supplied

[Blood component transfusion in full-term and premature new born infants].

BACKGROUND: Blood transfusion requirements for preterm infants are greater than for newborn ones. We compare blood transfusion requirements for newborn and premature infants and their pathology: clinical or surgical; hemorrhagic accidents and survival. METHODS: 48 newborns classified in 2 groups: 26 newborn and 22 preterm infants received 251 units of blood components: 177 units of red cell concentrates, 36 of platelet concentrates, 30 of fresh frozen plasma and 8 of total blood in a 186 days period. We analyzed total requirements of components in each group and daily, under a live-infant/day rate until 120 days. RESULTS: The all-components median requirements were 7.31 units for premature and 3.46 for newborn infants. Daily requirements analyzes reveal that requirements were greater before 60th day of life (d.l.) on clinical patients and after 86th d.l. may be caused by surgical acts. Hemorrhagic accidents happen on premature with less than 60,000 platelets/mm3. The survival wave by number of transfusions, until 186 d.l., show an inversely proportional trend between the number of transfusions done and the hope of life. CONCLUSIONS: Blood requirements for preterm infants are greater than for term ones. Those requirements are related to their pathology. Prophylatic platelet transfusions may reduce hemorrhagic accidents then red blood cell transfusions in preterm infants group. The number of transfusions over 10 is a surrogate marker of bad prognosis for both groups up to 120 d.l.

Blood Component Transfusion↗
PubMedDate not supplied

Aspergillary bronchopneumonia: an unusual cause of atelectasis and asphyxia in a leukemic patient.

A 22-year-old man in his first relapse of T-acute lymphoblastic leukemia developed fever and a pulmonary infiltrate after 23 days of granulocytopenia. Although having been under amphotericin B for 10 days, productive purulent cough ensued, with right lobe atelectasis and acute ventilatory failure that resolved after the elimination of a thick gelatinous bronchial plug. Sputum cultures yielded Candida Albicans and Staphylococcus epidermidis, and microscopic examination of the sputum plug disclosed Aspergillus hyphae. The patient died 9 days after, of a disseminated Aspergillus infection, confirmed by necropsy.

Adult↗
PubMedDate not supplied

[Benign systemic mastocytosis: report of 2 cases].

The case histories of two patients with benign systemic mastocytosis with skin involvement are presented. The first patient had urticaria pigmentosa diagnosed at the age of 2 months, and developed systemic disease within two years. The second presented urticaria pigmentosa at the age of 22 years while benign systemic mastocytosis was diagnosed 30 years later. The clinical findings in both cases were: skin involvement, hepatosplenomegaly and abdominal pain. The second patient had myelofibrosis. There was a favorable response to H1 and H2 histamine antagonist and ketotifen.

Adolescent↗