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Biomedical subjects

C Paul

Publications and source records attributed to C Paul.

At least 289 records · Page 16Linked to original sources
PubMed1983

Relative potency of dopamine agonists on autoreceptor function in various brain regions of the rat.

The effect of six dopamine agonists including apomorphine, epinine, dopamine, piribedil, lergotrile and bromocriptine on the incorporation of [3H]tyrosine into dopamine was studied in slices and synaptosomes prepared from various brain areas containing dopamine terminals including striatum, nucleus accumbens, olfactory tubercle and medial basal hypothalamus. It was observed that all of these drugs were active in causing a decrease in dopamine synthesis in these various brain areas. The catecholamine agonists apomorphine, epinine and dopamine were more potent in inhibiting dopamine synthesis in the mesolimbic structures than in the striatum. On the other hand, apomorphine and epinine were less potent while dopamine was more potent in the medial basal hypothalamus. The ergoline drugs were weak agonists in all structures studied. It is concluded that autoreceptor regulation of dopamine synthesis is more active in the mesolimbic compared with the nigrostriatal dopamine pathway while autoreceptors may be absent in the median eminence.

Animals↗
PubMed1982

Importance of the male factor in cancer of the cervix.

A woman's risk of cervical cancer is generally thought to be related to her sexual behaviour. The sexual background of her male partners is also important. In some societies, a woman's risk of cancer of the cervix will depend less on her own behaviour than on that of her partner. Male sexual behaviour, particularly in relation to prostitution, may account for two hitherto unexplained features of the epidemiology of this disease--the extremely high incidence in Latin America and the decline in mortality this century. If this is so and men carry the aetiological agent, it will be important to discover whether they do so for short or long periods.

Education↗
PubMed1982

Prednimustine and vincristine compared with cytosine arabinoside and thioguanine for treatment of elderly patients with acute nonlymphoblastic leukemia.

Sixty-seven patients with acute nonlymphoblastic leukemia (ANLL) and above the age of 60 years were randomly allocated to treatment with either prednimustine + vincristine or cycles with cytosine arabinoside and thioguanine. Of the 67 patients, 13 (19%) entered a complete remission and four a partial remission. Of 33 patients randomized to prednimustine and vincristine (15 adequately treated), three entered a complete remission and one a partial remission. Four further patients went into complete remission after a switch to other treatment modalities. Of 34 patients randomized to cycles of ARA-C and thioguanine (22 adequately treated), four entered a complete remission and three a partial remission with the correct program. One patient entered a remission with intermittent cytosine arabinoside + thioguanine (wrong program) and one further patient entered a complete remission after a switch to prednimustine and vincristine. Prednimustine + vincristine did not appear to be superior to treatment with cytosine arabinoside thioguanine cycles for elderly patients with ANLL.

Acute Disease↗
PubMed1982

Toxic effects of free and DNA-linked daunorubicin on isolated rat cardiac myocytes.

Isolated cardiac myocytes from adult rats were used as a model to study the cardiotoxicity of free and DNA-linked daunorubicin. The toxic effects on the myocytes were evaluated by studying morphological changes, trypan blue exclusion and cell membrane permeability to NADH, as determined by LDH-activity. At a concentration of 100 microM daunorubicin caused an increased plasma membrane permeability within 30 min. Using light microscopy, the myocytic injury induced by daunorubicin could be distinguished from that induced by anoxia or elevated pH. In contrast to the effect of the free drug, no toxic effects could be demonstrated after incubation with DNA-linked daunorubicin (100 microM) for 5 hours. The higher toxicity of the free drug was related to a much higher intracellular accumulation of daunorubicin. No fluorescent metabolites of daunorubicin could be detected in the myocardial cells. Daunorubicin did not induce lipid peroxidation, as judged by the absence of malondialdehyde production and evolution of ethane. It is concluded that daunorubicin exerts toxic effects on rat cardiac myocytes by mechanisms that do not involve lipid peroxidation. Isolated cardiac cells from adult rats seem to be a useful model for the further study of such mechanisms.

Animals↗
PubMed1982

Myocardial accumulation of 99Tcm-pyrophosphate and 99Tcm-gluconate compared with morphologic findings in daunorubicin treated rabbits.

In long-term daunorubicin treated rabbits increased myocardial accumulation of 99Tcm-pyrophosphate and 99Tcm-gluconate of a varying degree were recorded, visible at gamma camera examination in more than half of the animals. Chronic cardiomyopathy morphologically and topographically different from the ischemic myocardial injury was demonstrated in most animals at light microscopic examination. The myocardial abnormalities were classified in qualitative and quantitative scores and compared with the degree of isotope accumulation. The rabbits receiving a large single dose of daunorubicin had slightly increased isotope accumulation in the myocardium but no histopathologic changes.

Animals↗
PubMed1982

Caiman crocodylus hemoglobin. Complete primary structures of alpha and beta chains; phylogenic and regulatory aspects.

In some reptiles, the hemoglobin oxygen affinity is lowered by CO2 and not by the usual phosphate cofactors. To understand the molecular mechanism of this regulation, Caiman crocodylus hemoglobin's primary structure has been determined. The alignment of the 141 residues of the alpha chain as well as the 146 of the beta chain were obtained by classical method of sequence analysis and are compared with some mammalian, avian, amphibian, and fish hemoglobin chains. Furthermore, from these sequences, it is possible to explain the non-interaction of phosphorylated cofactors with the caiman deoxyhemoglobin on the basis of mutations of the amino acids responsible for their fixation on the beta chain. Among these residues only lysine beta 82 is unchanged. In addition a site has been proposed for the fixation of HCO3- which involves ionic bonds with serine beta 1 and glutamic acid beta 144 (Perutz et al. (1981) Nature 291, 682-684) (1).

Alligators and Crocodiles↗
PubMed1981

Reducing the cardiotoxicity of anthracyclines by complex-binding to DNA: report of three cases.

Three patients with acute myeloblastic leukemia received high doses of daunorubicin, first in the free form and later as complex with DNA. Two of the patients also received doxorubicin-DNA. Two patients showed symptoms of cardiotoxicity with signs of congestive heart failure after cumulative doses of 910 and 250 mg of noncomplexed daunorubicin/m2 body surface area, respectively. Thereafter they tolerated daunorubicin-DNA complex up to total doses of 1430 mg and 1200 mg daunorubicin/m2, respectively, with no further signs of cardiotoxicity. One of them entered another complete remission after therapy with the complex. The third patient had received 820 mg daunorubicin/m2 and was in his second relapse when he was switched to daunorubicin-DNA complex. A new remission was induced and the patient received a total daunorubicin dose of 1480 mg/m2 with no clinical signs of cardiotoxicity. However, a cardiac biopsy showed minor myocardial changes, which could have been due to daunorubicin. During a third relapse the patient received 270 mg/m2 doxorubicin-DNA. At autopsy still only minor signs of cardiomyopathy were seen. Thus, complex-binding of anthracyclines with the DNA appears to enhance the usefulness of these drugs in the treatment of patients with leukemia.

Adult↗
PubMed1981

Comparison of daunorubicin and daunorubicin-DNA complex in the treatment of acute nonlymphoblastic leukemia.

Sixty consecutive patients, 15-60 years old, with ANLL were divided randomly into three groups for induction treatment with one of the following regimens: R1, daunorubicin (DNR) 1.5 mg/kg on day 1 + ARA-C 2 mg/kg body weight on days 1-5; R2, DNR 1.5 mg/kg on days 1 and 2 + ARA-C 2 mg/kg on days 4-8; R3, DNR-DNA complex 1.5 mg/kg on days 1 and 2 + ARA-C 2 mg/kg on days 4-8. Maintenance treatment consisted of monthly courses of DNR 1.5 mg/kg (R1, R2) or DNR-DNA 1.5 mg/kg (R3) combined with ARA-C 1 mg/kg on days 1-5, alternating with thioguanine 2 mg/kg PO on days 1-5 combined with ARA-C 1 mg/kg IV on days 1-5. Fourteen patients of 20 went into complete remission with R1, 13 or 18 with R2, and 15 of 22 with R3. The overall remission frequency was 70% and there was no significant difference between the different groups. The median time in first remission and the median survival time were 300 and 510 days, respectively, with R1; 335 and 495 days with R2; and 295 and 677 days with R3. There was no statistically significant difference between the groups treated according to the different regimens concerning the time in first remission. Survival was slightly better with R3 than with R1. Treatment with the DNR-DNA complex caused less pronounced thrombocytopenia and fewer 'minor' cardiac abnormalities than treatment with free DNR in the same dosage schedule.

Acute Disease↗
PubMed1981

Thermography in the diagnosis of DVT.

161 consecutively admitted medical patients with the clinical suspicion of acute deep venous thrombosis (DVT) were thermographed and phlebographed in order to study the congruence of these methods. The sensitivity of thermography in the detection of DVT was found to be 99%, whereas the specificity was only 49%. The low specificity is explained by the fact that all thermographs suggestive of DVT were classified as pathologic to keep the sensitivity of the method as high as possible. Patients with dilated veins which may closely resemble DVT on thermography may in these cases give false positive results. Of 76 patients with phlebographically verified DVT, 22% became thermographically normal within 22 days, whereas 78% did not normalize within the mean observation time of 31 days. In another part of the study all medical patients (101) who were residing in our wards during a period of a week were screened by means of thermography. From this unselected group 17 patients were found to have thermographs suggestive of DVT. In 5 of these patients no reason for pathological thermography could be found. Thermography is a cheap and highly sensitive screening method for DVT, but findings of false positives caused by older thromboses and dilated veins are not unusual. The frequency of such false positives may be minimized by performing thermography after exercise.

Acute Disease↗
PubMed1980

Determination of daunorubicin and its main metabolites in plasma, urine and leukaemic cells in patients with acute myeloblastic leukaemia.

The pharmacokinetics of daunorubicin were studied in 3 previously untreated patients with acute myeloblastic leukaemia by simultaneous monitoring of daunorubicin (DNR), daunorubicinol (DOL) and their aglycones in plasma, urine and leukaemic cells. The drug was given as an i.v. infusion in a dose of 1.5 mg/kg body wt. The plasma concentration of daunorubicin declined rapidly after the infusion. The concentration of daunorubicinol exceeded that of the parent compound only 5 min after the end of the infusion. Daunorubicin accumulated extensively in the leukaemic cells and reached concentrations there which exceeded the plasma concentration 400-4000 times. As compared to what was found in plasma, daunorubicinol appeared much slower in the leukaemic cells and the concentration ratio only reached 30-200. The concentration of aglycones was low in the leukaemic cells as well as in plasma. Only about 15% of the administered dose of daunorubicin could be recovered in the urine within 4 days, most of it as daunorubicinol. The results demonstrate that the plasma concentration of daunorubicin and its metabolites provides little information on the drug concentration in the leukaemic cells. Direct determinations of drug concentrations in the leukaemic cells might be of clinical value for optimization of the therapy in acute leukaemia.

Adult↗
PubMed1979

N-(5-Phosphoribosyl)anthranilate isomerase-indoleglycerol-phosphate synthase. 2. Fast-reaction studies show that a fluorescent substrate analogue binds independently to two different sites.

The mechanism of binding of reduced 1-(2-carboxyphenylamino)-1-deoxyribulose 5-phosphate (rCdRP) to two different binding sites on the bifunctional enzyme is determined by kinetic studies, using temperature-jump and stopped-flow equipment with fluorescence detection. Two rapid binding processes and a comparatively slow isomerization process are observed over a wide range of enzyme and rCdRP concentrations. Kinetic measurements with low concentrations of rCdRP show that the isomerization is coupled only to the more rapid of the two binding reactions that involves the active site of indoleglycerol-phosphate synthase. The slower of the two binding reactions represents rCdRP binding in one step to the active site of (phosphoribosyl)anthranilate isomerase. The simplest mechanism explaining quantitatively the dependence of the relaxation times on concentration consists of rCdRP binding to two sites on the enzyme that are intrinsically different and independent, even to the extent that a ligand-induced isomerization of one site is not transmitted to the other site. Simulation studies show that the concentration dependences of the amplitudes of the three relaxation processes are also consistent with the mechanism. The results are discussed in terms of two autonomous domains of folding of the polypeptide chain.

Carboxy-Lyases↗
PubMed1979

Uptake of free and DNA-bound daunorubicin and doxorubicin into human leukemic cells.

Leukemic cells from seven patients with acute nonlymphoblastic leukemia and granulocytes, and mononuclear cells from three healthy controls were isolated by centrifugation on metrozoate-dextran. The intracellular accumulation of both the free and DNA-bound forms of daunorubicin and doxorubicin was studied in vitro. The uptake of unbound daunorubicin was higher than that of doxorubicin. At drug concentrations of 1.75 microM and higher the uptake of the free drugs was greater than that of the bound forms, but at lower drug concentrations the uptake was about the same. This could at least partly be explained by a greater dissociation of the DNA-drug complexes at lower drug concentrations. The uptake into normal leukocytes was of the same order of magnitude as that into leukemic cells. There was a great interindividual variation in the accumulation of both free and DNA-bound drugs in the cells from leukemic patients. This variation might be of importance for the prediction of individual sensitivity to the different drugs.

Bone Marrow Cells↗
PubMed1979

Treatment of acute nonlymphoblastic leukemia in adults with daunorubicin-DNA complex: a preliminary report.

Forty-four adult patients under 60 years of age with acute nonlymphoblastic leukemia were randomized for induction treatment with one of the following three regimens: R 1 = courses of daunorubicin on day 1 + ARA-C on days 1--5; R 2 = courses of daunorubicin on days 1 and 2 + ARA-C on days 4--8; R 3 = courses of daunorubicin-DNA complex on days 1--2 + ARA-C on days 4--8. Out of 14 patients, 9 went into remission on R 1, 6 out of 14 on R 2, and 8 out of 16 on R 3. The preliminary results suggest that daunorubicin-DNA complex has the same efficacy for inducing remission as daunorubicin alone, if the same time intervals and dosages are used.

Acute Disease↗
PubMed1979

Comparison of a new microcrystalline dicoumarol preparation with warfarin under routine treatment conditions.

1 To determine whether two different oral anticoagulants show difference under routine clinical conditions, 71 patients were randomized to treatment with Apekumarol, a microcrystalline dicoumarol preparation, and 72 patients to treatment with warfarin. 2 During the inpatient phase of treatment both drug groups remained for about 94% of their treatment time within prothrombin value limits of 5-25% (Simplastin A). No statistically significant difference was found between the drugs. 3 While under outpatient care, both drug groups remained for about 80% of their treatment time within prothrombin value limits of 5-25%. No statistically significant difference was found between the drugs. 4 The intensity of control and number of prothrombin-determinations did not differ significantly between the groups. 5 Variations in the daily dose did not differ significantly between the groups. 6 The mean daily dose could not be correlated to mean body weight. 7 The mean daily dose decreased with age for the male patients taking warfarin, not for the female patients. There was no such decrease for either male or female patients taking Apekumarol. An additional 137 patients who at the time of the trial were under routine treatment with warfarin were also studied with regard to mean daily dose, age and sex. In this additional group the mean daily dose could be correlated with age in both males and females. 8 No difference between Apekumarol and warfarin could be demonstrated when tested under routine clinical conditions according to the design of the present study. Sensitivity for warfarin, but not for Apekumarol, seems to increase with age, this sensitivity has been demonstrated in both sexes.

Adult↗