Fixed combinations of delapril plus indapamide vs fosinopril plus hydrochlorothiazide in mild to moderate essential hypertension.

This 12-week randomized, parallel-group, multicenter study compared fixed combinations of delapril (D) 30 mg plus indapamide (I) 2.5 mg and fosinopril (F) 20 mg plus hydrochlorothiazide (H) 12.5 mg in 171 adult patients with mild to moderate essential hypertension. After a 2-week placebo run-in, sitting and standing systolic (SBP) and diastolic blood pressure (DBP) was measured by conventional sphygmomanometry. The primary efficacy endpoint was the percentage of normalized (sitting DBP < or =90 mm Hg) and responder (sitting DBP reduction of 10 mm Hg or DBP < or =90 mm Hg) patients. Treatment effects were analyzed in the intention-to-treat (ITT; n = 171) and the per-protocol (PP; n = 167) populations. The percentage of normalized and responder patients did not differ significantly between the D + I (87.4% and 92%) and the F + H (81% and 86.9%) ITT groups. Similar results were seen in the PP population. In ITT and PP patients, sitting and standing SBP and DBP values were comparable at baseline in the two groups and were significantly (P<.01) and similarly reduced at weeks 4, 8, and 12. Neither treatment induced reflex tachycardia, and both regimens were well tolerated. Four patients in the F + H group dropped out because of adverse events. In this study, the efficacy and safety of D + I were comparable to those of F + H in patients with mild to moderate essential hypertension.

Current role of immunoscintigraphy in malignant melanoma follow-up. A study of 114 patients.

Although its role and importance is debated, Immunoscintigraphy (IS) remains a popular technique in Malignant Melanoma (MM) follow-up for postoperative assessment. Between April 1990 and December 1996, 287 consecutive patients underwent 650 IS examinations at our Department. Only data on 114 patients, operated up to December 1993, with a follow-up of at least 7 years are given here. IS results were compared to physical examination, to other imaging modalities and, where available, to histology. IS specificity and sensivity, concerning detection of melanoma metastases in lymph nodes, skin, brain, lung, visceral sites and bone, ranged from 37.5% and 22% to 100%. Our results indicate a high diagnostic accuracy of IS only for lymph node examination, but not for other possible locations of melanoma metastases. In our experience IS cannot be recommended for staging of melanoma patients, and should only be used in association with other imaging modalities.

Bioequivalence of levothyroxine tablets administered to a target population in steady state.

Two parallel trials were carried out with levothyroxine sodium salt in 50 and 100 microg strengths, respectively, giving 100 microg day-1(50x2 microg day-1 or 100x1 microg day-1) in both trials in a repeated dose regimen. Twenty patients suffering from primary hypothyroidism under treatment with 100 microg day-1 of thyroxine sodium salt were enrolled in each trial. They were clinically and chemically euthyroid. Each trial lasted 114 days, with 57 days being devoted to the first treatment (test or reference) and 57 days to the other (reference or test), according to a two-period, two-sequence, two-formulation design in a steady state without wash-out. The test formulation was prepared with a technological improvement and is being produced to replace that at present on the market. Serum concentrations of free and total levothyroxine, and free and total levotriiodothyronine were assayed repeatedly during the treatment and in timed samples after the last dose of each formulation, using radioimmunoassays. Cmax and AUCss,tau were considered to be target parameters for bioequivalence which was assessed through 90% confidence intervals in the 0.80-1.25 range, as required by EU and US FDA operating guidelines. The results have shown that of these hormones, the free and total parent compound thyroxine is that which most clearly showed a peak after dosing, whereas its metabolite, free and total triiodothyronine, fluctuated around pre-dose concentrations. Bioequivalence was fully assessed with Cmax and AUCss,tau, with all four hormones tested and at both strengths administered. The two test formulations in 50 and 100 microg are thus bioequivalent with the two reference preparations. Tolerability was very good in all cases.

Cytogenetic evaluation of 20 primary breast carcinomas.

Chromosome analysis was performed on samples from 20 Brazilian patients with breast cancer. All the samples were from untreated patients who presented the clinical symptoms for months or years before surgical intervention. Six cases showed axillary lymph node metastases. Clonal chromosome abnormalities were detected in all cases. The numerical alterations most frequently observed involved the loss of chromosomes X, 19, 20, and 22 followed by gain of chromosomes 9 and 8. Among the structural anomalies observed, there was preferential involvement of chromosomes 11, 6, 1, 7, 3, and 12, supporting previous reports that these chromosomes may harbour genes of importance in the development of breast tumors. Two cases with a family history of breast cancer had in common total or partial trisomy 1.

Divided nevus of the eyelid: a case report.

Divided nevus of the eyelid as a rare pathologic entity and develops during fetal growth, when the two eyelids are still fused together. Its surgical treatment is mostly based on full thickness skin grafts. We report a case of a 22-year-old woman with a congenital divided nevus affecting the left upper and lower eyelid. The patient was treated in our Department because of the onset of a purple red nodule in the lower part of the nevus. We examined the case from embryological, histopathological, clinical, and diagnostic standpoints, and discuss surgical options in order to reach an optimal functional and aestetic result.

Chaos: a potential problem in the biological control of insect pests.

Erratic variations are normally observed in the populations of insect pests that destroy crop plants. To establish a scientific basis for developing effective control procedures, we have developed a model system for the European Corn Borer (ECB) (Ostrinia nubilalis) for which extensive field data, as well as laboratory results, have been accumulated during the past four decades. The model includes both a natural ECB pathogen and a genetically engineered toxin-producing agent as possible means of biological control. Our aim was to determine the conditions that could cause the population to vary erratically, as observed in the field. The erratic behavior in our simulations was analyzed to determine whether it is chaotic; chaos is a distinct type of erratic behavior which shows extreme sensitivity to initial conditions, i.e., the starting size of the population. Our simulations show that an increase in the death rate of the infected ECB, or a decrease in the birth rate of uninfected ECBs from infected ones, variables that are known to be affected by weather conditions, can induce a chaotic regime in which ECB population peaks reach values far higher than before chaos set in. Population peaks are even greater in the presence of both biological control agents. The results show that a biological control regime cannot be effective under conditions that induce chaotic population dynamics. Microcosm studies could be used to determine whether this situation would occur in the field.

Inhibition of SV40 DNA replication by benzo[a]pyrene diol epoxide adducts: two recovery modes.

Anti-benzo[a]pyrene diol epoxide (BPDE) adducts produced in vitro in SV40 initially inhibit SV40 DNA replication in vivo, in cells unexposed to BPDE. A single adduct in a replicon is probably sufficient to block DNA replication. The recovery process appears to begin immediately after infection. The rate of recovery of replicative capacity is inversely related to the initial adduct number. Holding the infected cells temporarily under conditions that prevent viral DNA replication results subsequently in increased recovery, proportional to the holding time. The mechanism of recovery appears to be constitutive and prereplicative. In addition, there is a second mode of recovery which is induced by pretreatment of the host cells with BPDE before infection. The effect of pretreatment is similar to that of extending the holding time before replication: the first molecules begin to replicate earlier but the subsequent rate of recovery is unchanged. The induced mechanism may be either a limited stoichiometric repair process or a slow replicative bypass.

Termination of DNA synthesis in vitro at apurinic sites but not at ethyl adducts on the template.

The effects of DNA lesions produced by the carcinogenic alkylating agents ethylnitrosourea and diethylsulfate on the extent of DNA synthesis have been studied in a system utilizing circular single-stranded phiX174 DNA as template and a 392-base restriction fragment as primer with E. coli polymerase I (Klenow fragment). Apurinic sites produced by loss of unstable ethylated bases from the template terminate DNA synthesis at the first such site encountered, but ethyl adducts at most, if not all, locations permit readthrough.

The major adducts of cis and trans benzo[a]pyrene diol epoxides cause chain termination during DNA synthesis in vitro.

We have studied DNA synthesis in vitro using as template phi X174 DNA containing varying numbers of adducts formed by reaction with cis and trans benzo[a]pyrene (BP) diol-epoxides. The extent of DNA synthesis decreases with increasing numbers of adducts and there is a concomitant decrease in the size of the DNA products. Both decreases can be accounted for quantitatively by the assumption that synthesis terminates at every BP adduct. Since the majority of the adducts are located at the 2-amino group of guanine, we deduce that these adducts cause termination. The role of adducts at other sites is uncertain. The cis and trans BP diol-epoxides are indistinguishable with regard to chain termination, yet in vivo these isomers behave differently. These results suggest that chain determination alone is insufficient to account for the mutagenic effects of BP diol-epoxides.

Effects of ethylating agents on DNA synthesis in vitro: implications for the mechanism of carcinogenesis.

A highly carcinogenic ethylating agent, ethylnitrosourea (ENU), and a weakly carcinogenic one, diethylsulfate (DES) react with DNA to roughly the same extent but DES produces about 6 times as many unstable ethylated bases, which are gradually lost spontaneously under physiological conditions. The different rates of loss for the different DNA bases have been studied using polydeoxyribonucleotides. Spontaneous strand breakage following base loss is slow, lagging more than a week behind base loss at 37 degrees C; ultimately, DES results in much more spontaneous strand breakage than ENU. In DNA synthesis in vitro, using avian myeloblastosis virus (AMV) polymerase, no nucleotides are incorporated opposite missing bases in the template; when the template contains ethylated bases that are impaired in their ability to form specific hydrogen bonds, purine-pyrimidine mispairing can occur and mismatched nucleotides are incorporated into the daughter strand. ENU ethylates somewhat more sites leading to mispairing potential than DES. ENU also produces approximately 7.5 times more ethyl phosphotriesters than DES.

Effects of benzo(a)pyrene adducts of DNA synthesis in vitro.

Two diol epoxides of benzo(a)pyrene (BP), and benzo(a)pyrene 4,5-oxide, have been used to make adducts in the homopolymers polyribocytidylic acid, (rC); polyriboadenylic acid (rA), polydeoxycytidylic acid (dC) and polydeoxyadenylic acid (dA). With appropriate oligomers as primers these modified and unmodified polynucleotides were used as templates for DNA synthesis with avian myeloblastosis virus DNA polymerase (AMV) or E. coli Pol I DNA polymerase. We have found that: (1) the size of the DNA product is not markedly decreased by the presence of these these polycyclic aromatic hydrocarbon adducts in the templates; (2) the presence of adducts does not lead to increased incorporation of erroneous bases. These results, supported by kinetic data, suggest that these polymerases can bypass a site containing an adduct on the template without leaving a gap or causing misincorporation of a base and they imply that mutagenesis by BP may not be attributable to either of these mechanisms.

Inhibition of reverse transcription of 70S and 35S avian myeloblastosis RNAs by nonprimer tRNA's.

We studied the kinetics of the reverse transcription of 70S and 35S RNA of avian myeloblastosis virus in the presence and absence of various tRNA's. All tRNA's inhibited synthesis. tRNA's from Escherichia coli and yeast exhibited a noncompetitive type of inhibition, i.e., they bound reversibly and randomly and did not alter the affinity of the viral RNA for the polymerase. Nonprimer tRNA's obtained from 70S RNA molecules produced a complex pattern of inhibition. The results show that the nonprimer tRNA's which bound to the reverse transcriptase decreased the affinity of the viral RNA for the enzyme. The maximum rate of synthesis with 70S RNA as the template was less than that with 35S RNA, presumably because the former contains nonprimer tRNA's which can interact with the polymerase.

Characterization of a DNA polymerase associated with an endogenous DNA-synthesizing complex isolated from human lymphoid cells.

We have shown that a membrane fraction prepared from isolated human lymphoid nuclei contains endogenous DNA-synthesizing activity which is sensitive to RNAase. We have isolated a DNA polymerase from this fraction and partially purified it to what we estimate as about 10 000-fold. Its chromatographic behavior, template specificity, sedimentation constant, pH optimum, and sensitivity to N-ethylmaleimide suggest that the activity resembles but is not identical to DNA polymerase gamma (formerly called R-DNA polymerase). The membrane fraction also contains a minor activity which is due to polymerase beta, the low molecular weight (3.5 S) nuclear enzyme.

Mechanism of interaction of avian myeloblastosis virus reverse transcriptase with avian myeloblastosis virus RNA.

The synthesis of DNA on avian myeloblastosis virus (AMV) RNA as the primer-template using AMV reverse transcriptase in vitro has been examined as a function of the concentrations of these components, as well as a function of the ionic strenth of the assay medium. The results are consistent with the hypothesis that two types of sites exist on the AMV RNA: inactive "dead-end" sites that merely bind the enzyme, and active binding sites that lead to DNA synthesis. Velocity sedimentation studies of reverse transcriptase reveal that the enzyme becomes a dimer (or oligomer) at low salt concentrations and it is at these concentrations that the two types of sites are evident on the RNA. At high salt concentration the enzyme, which exists primarily as a monomer, is inactive with AMV RNA, although it is active when poly(rA)dT10 is used as the primer-template. We have shown that inactive sites are not due to binding of the reverse transcriptase to nicked regions or to partially denatured RNA molecules. We deduce that inactive sites are those containing incorrect 4S primer molecules. These results are discussed in terms of the mechanism of the interaction of the reverse transcriptase with AMV RNA.

E. coli tRNAs as inhibitors of viral reverse transcription in vitro.

Reverse transcription of 70S AMV RNA by AMV reverse transcriptase has been studied in the presence of E. coli tRNAs. We have shown that inhibition of DNA synthesis occurs and that the tRNAs bind to the enzyme and not to the 70S RNA. The results have implications for the control of reverse transcription in vivo.

In vitro DNA synthesis on smooth membranes observed by fluorescence.

Smooth membranes have been isolated from a human diploid line of lymphocytes. These membranes exhibit an endogenous DNA-synthesizing capability which is partially destroyed by prior treatment with RNase. In order to ascertain the role of the membranes in the DNA synthesis we have examined the conformation of the membrane proteins by observing fluorescence changes of the intrinsic probe, tryptophan. We have observed that on addition of the deoxynucleoside-5'-triphosphates, which permits DNA synthesis, there are fluorescence changes due to the tryptophan residue; when DNA synthesis is prevented by omitting some of the precursor triphosphates, fluorescence changes are absent. These effects have been observed with plasma and nuclear membrane fractions; the former may contain a small fraction of the latter. Similar membrane preparations from non-lymphoid cells do not process the endogenous DNA-synthesizing system, as shown by the lack of incorporation of radioactive precursors of fluorescence changes.

Extent of double strandedness in avian myeloblastosis virus RNA.

The extent of double strandedness of avian myeloblastosis virus 70S RNA has been determined from fluorescence measurements of the intercalation of ethidium bromide. We have shown that 50% of the nucleotides of 70S RNA in solution are in a stable helical configuration. This value does not include small helical regions that are too unstable to permit intercalation of the dye. The avian myeloblastosis virus RNA as it exists within the virion has the same degree of helicity as the free 70S RNA. Heating the free 70S RNA to 55 or 70 C, followed by cooling, does not measurably change the degree of helicity; the subunits therefore have as much helicity as the parent molecule.