Autonomous replication sequences in the maxicircle kinetoplast DNA of Leishmania tarentolae

Four fragments from the maxicircle DNA of Leishmania tarentolae cloned into the selectable Saccharomyces cerevisiae shuttle vector, YIp5, exhibited autonomous replicating sequence (ars) activity. Two of the fragments (pSK120, pSK152) produced large yeast transformant colonies and two (pSK30, pSK150) produced small colonies. All yeast transformants contained extrachromosomal self replicating YIp5 hybrid plasmids as shown by mitotic instability in non selective medium and by the transformation of Escherichia coli with yeast minilysates and recovery of the plasmid from the transformed bacteria. The copy numbers of pSK30, pSK150 and pSK152 in the transformed yeast were approximately the same as that of the YRp12 control, which contains the yeast arsl element; the copy number of pSK120, however, was at least 10 fold lower. A 1.87 kb subfragment of the pSK120 fragment also showed strong ars activity. The entire DNA sequences of the pSK120, pSK152 and pSK150 fragments are known, and several yeast 11 mer consensus ars sequences are present within each fragment. In addition there is a sequence (Lt ars 189) within the pSK152 subclone that has 78% similarity with a 189 nt sequence of an ars element from the Crithidia fasciculata maxicircle (Cf ars 189), implying an evolutionary conservation of this putative origin of replication in at least two different kinetoplastid species. The relative positions of the Lt ars 189 sequence in the L. tarentolae maxicircle map and the Cf ars 189 sequence in the C. fasciculata map with respect to the 9 and 12 S ribosomal genes are similar, implying an overall conservation of gene order in this portion of the transcribed regions of these two species and perhaps in all kinetoplastid species.

Phorbol esters inhibit murine B cell differentiation to immunoglobulin secretion but not proliferation

Bacterial lipopolysaccharide (LPS) induces resting B cells to proliferate and to secrete IgM. We have found that addition of phorbol esters (PE) such as phorbol myristate acetate (PMA) to murine B cells specifically inhibits LPS-induced IgM secretion but not proliferation. PMA is extremely potent, with half-maximal inhibition occurring at about 10 pM. The effect on B cells appears to be due to interaction with PE receptors, because a series of PE have similar potencies for tumor promotion, binding to receptors, and inhibition of IgM secretion. PE also inhibit IgM secretion induced by T cell-derived lymphokines and LPS-induced IgG secretion. Results of these studies suggest that the protein kinase C, with which PE interact, plays an important role in the regulation of B cell differentiation and may also provide a powerful tool for dissecting molecular events involved in induction of Ig secretion.

Phorbol esters inhibit murine B cell differentiation to immunoglobulin secretion but not proliferation

Bacterial lipopolysaccharide (LPS) induces resting B cells to proliferate and to secrete IgM. We have found that addition of phorbol esters (PE) such as phorbol myristate acetate (PMA) to murine B cells specifically inhibits LPS-induced IgM secretion but not proliferation. PMA is extremely potent, with half-maximal inhibition occurring at about 10 pM. The effect on B cells appears to be due to interaction with PE receptors, because a series of PE have similar potencies for tumor promotion, binding to receptors, and inhibition of IgM secretion. PE also inhibit IgM secretion induced by T cell-derived lymphokines and LPS-induced IgG secretion. Results of these studies suggest that the protein kinase C, with which PE interact, plays an important role in the regulation of B cell differentiation and may also provide a powerful tool for dissecting molecular events involved in induction of Ig secretion.

Sequence heterogeneity and anomalous electrophoretic mobility of kinetoplast minicircle DNA from Leishmania tarentolae

Several unit-length minicircles from the kinetoplast DNA of Leishmania tarentolae were cloned into pBR322 and into M13 phage vectors. The complete nucleotide sequences of three different partially homologous minicircles were obtained. The molecules contained a region of approx. 80% sequence homology extending for 160-270 bp and a region unique to each minicircle . A 14-mer was found to be conserved in all kinetoplast minicircle sequences reported to date. The frequency distributions of various minicircle sequence classes in L. tarentolae were obtained by quantitative gel electrophoresis and by examination of the "T ladder" patterns of minicircles randomly cloned into M13 at several sites. By these methods we could assign approx. 50% of the total minicircle DNA into a minimum of five sequence classes. A sequence-dependent polyacrylamide gel migration abnormality was observed with several minicircle fragments both cloned and uncloned. The abnormality was dependent on the presence of a portion of the conserved region of the minicircle .

Hyperfractionated total body irradiation for bone marrow transplantation. Results in seventy leukemia patients with allogeneic transplants

From May, 1979 to March, 1981, 76 leukemia patients were prepared for bone marrow transplantation (BMT) with a new hyperfractionated total body irradiation (TBI) regimen (1320 cGy in 11 fractions, 3x/day), followed by cyclophosphamide, 60 mg/kg, for two days. Partial lung shielding was done on each treatment, with supplemental electron beam treatments of the chest wall to compensate, and of the testes, a sanctuary site. This regimen was initiated to potentially reduce fatal interstitial pneumonitis as well as decrease leukemic relapse. These patients were analyzed in May, 1982, for a minimum follow-up of 14 months. Overall actuarial survival at 1 year for acute non-lymphocytic leukemia (ANLL) patients is 63%, while relapse-free survival at 1 year is 53%. For those ANLL patients who underwent BMT while in remission (first, second, and third combined), relapse-free survival is 61% at 1 year compared with 40% for those patients who had their BMT at the time of relapse (greater than or equal to 10% blasts in marrow). On the other hand, for acute lymphocytic leukemia (ALL) patients, there is no significant difference between relapse or remission patients with regard to overall survival or relapse-free survival, when relapse is defined as greater than 5% blasts in the marrow at the time of cytoreduction. Overall actuarial survival at 1 year for ALL is 61% and relapse-free survival is 45% at 1 year. Patients with ALL who had their BMT cytoreduction at the time of relapse have a survival equal to that of our remission patients, and greater than that of patients in relapse cytoreduced with a single dose as reported by others. However, patients with greater than or equal to 10% blasts have not fared as well, having only a 22% 1 year relapse-free survival compared with a 68% 1 year relapse-free survival for patients with less than 10% blasts. Fatal interstitial pneumonitis has dropped to 18% compared with 50% in our previous single-dose TBI regimen (1000 cGy), in which the same doses of cyclophosphamide were given prior to TBI. In conclusion, not only has fatal interstitial pneumonitis been reduced by hyperfractionation and partial lung blocking, but there may be a survival advantage in ALL patients in relapse, who have a survival equal to that of remission patients. This may indicate a greater cell kill with the higher dose (1320 cGy) attained with this regimen, in these patients with a higher leukemic cell burden.

Comparison of maxicircle DNAs of Leishmania tarentolae and Trypanosoma brucei

The conserved portions of the maxicircle DNAs of Leishmania tarentolae and Trypanosoma brucei are organized in a basically colinear manner over a 15- to 17-kilobase region that is interrupted by two small less-homologous sequences. The most highly conserved regions are those encoding the 9S and 12S genes. An approximately 12-kilobase region directly upstream of the 12S gene in the L. tarentolae maxicircle showed no sequence homology with the T. brucei maxicircle and also was not transcribed. An approximately 6-kilobase region in the T. brucei maxicircle in the same relative location also showed no sequence homology with the L. tarentolae maxicircle. We propose that evolution of maxicircle DNA occurs mainly within this "divergent region."

The use of different induction and maintenance chemotherapy regimens for the treatment of advanced yolk sac tumors

Four children with yolk sac tumor were treated with an aggressive combination chemotherapy program. Three children had presacral primary tumors, one having pulmonary metastases, and one had a testicular primary tumor with pulmonary metastases. Three children were treated when they had measurable disease, and one had no measurable disease. The chemotherapy program consisted of a 6-wk induction period with vincristine (VCR), cis-diamminedichloroplatinum (DDP), and bleomycin. Maintenance therapy consisted of VCR, actinomycin D, and cyclophosphamide (cytoxan) every 3-4 wk as tolerated. Treatment was discontinued after 12 mo of complete remission. All three patients with evaluable disease had a partial response (PR) to induction therapy. Two underwent surgical exploration following induction therapy, one a laparotomy and the other a thoracotomy, and were found to have only scar tissue at the sites of presumed residual disease. The third child with measurable disease progressed to a clinical complete response (CR) during maintenance therapy. Two patients have had no evidence of disease (NED) for 42+ and 41+ mo since starting therapy (28+ and 27+ mo since completing treatment). Two patients are NED 11+ and 7+ mo since starting therapy and remain on treatment. We have encountered no significant renal or pulmonary toxicity, and there have been only two hospitalizations during maintenance therapy for fever and neutropenia. These preliminary results employing different induction and maintenance chemotherapy programs and planned second-look surgical intervention appear encouraging.

Evaluation of the chronic hepatic toxicity of 6-mercaptopurine in the wistar rat

The ability of choline (C) to prevent hepatic toxicity due to chronic administration of 6-mercaptopurine (6-MP) was evaluated in male Wistar rats. Two dose levels of 6-MP and two dose levels of C were used. Choline did not prevent or diminish the hepatic accumulation of triglyceride when administered in combination with 6-MP. The 6-MP did impair the growth of the experimental animals, and this effect was antagonized by C administration. The data provided experimental support for the clinical observation of growth impairment in children treated with chronic antimetabolite therapy for acute lymphoblastic leukemia.

Identification of maxicircle DNA sequences in Leishmania Tarentolae that are homologous to sequences of specific yeast mitochondrial structural genes

Sequences homologous to the yeast mitochondrial structural genes for cytochrome oxidase subunits I and II, ATPase 6 and cytochrome b were identified on the kinetoplast DNA maxicircle molecule by low stringency hybridization of maxicircle blots with heterologous probes derived from mitochondrial DNA of yeast petite mutants. No hybridization was observed with the yeast ATPase 9 gene probe. The relative extent of base sequence mismatch was determined by melting of the heterologous hybrids. Candidates for the transcripts of these presumptive structural genes were proposed with reference to the transcriptional map of the maxicircle of Leishmania tarentolae. These results provide the first indication that maxicircle DNA specifies information for a limited number of conserved mitochondrial gene products similar to those already described for other eukaryotic cells.

Transcription of the maxicircle kinetoplast DNA of Leishmania tarentolae

Numerous transcripts of the 30 kilobase maxicircle component of the kinetoplast DNA of Leishmania Tarentolae have been analyzed by the Northern blotting method. The transcripts range in size from 1.8 to 0.1 kb. RNAs arising from the cloned 6.6 kb region containing the presumptive miniribosomal RNA genes were shown to be transcribed in the direction 12 S to 9 S on the same strand. A preliminary transcriptional map was constructed and related to the distribution of AT-rich regions of the maxicircle DNA molecule.

Isolation and characterization of drug resistant mutants of Crithidia fasciculata

Mutants of Crithidia fasciculata, resistant to Actinomycin D, Tubercidin, Crystal Violet, 6-Azauridine, and 5-Fluorouracil were obtained and characterized. The mutants were stable when maintained under nonselective conditions, and could be grouped in several subclasses on the basis of cross-resistance to other drugs. Actinomycin D- and Crystal Violet-resistant mutants appeared spontaneously whereas the others appeared only after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Analysis with a cell sorter indicated no large scale meiotic changes in ploidy under the various culture conditions employed. These mutants may provide suitable, selectable, genetic markers for use in studying the possibility of a sexual mating process in Crithidia.

Recovery from aspermia induced by low-dose radiation in seminoma patients

Gonadal dosimetry and spermatogenic activity was monitored in patients given radiation therapy (RT) after unilateral orchiectomy for seminoma. The RT given was, with minor variations, 3200 rad in 16 fractions in four weeks to the para-aortic and ipsilateral pelvic inguinal lymphatics in order to include the orchiectomy scar. The incidental amount of radiation to the remaining testicle averaged 78.4 +/- 7.4 rad and ranged from 32-178 rad as determined by thermoluminescent dosimetry. Induction of aspermia was documented in ten out of 14 patients who received over 65 rad to the gonad. At lower doses, aspermia may not have occurred or was of short duration. Recovery of sperm in the semen occurred in 12 patients within 30-80 weeks after start of treatment. The data suggest that the time of recovery may be dose dependent within the range of 19-148 rad. During the period of recovery, patients with oligospermic semen may be fertile and should be so advised.

Long-term survival determinants in Wilms' tumor

This is a retrospective report of 54 patients with the diagnosis of Wilms' tumor treated at Roswell Park Memorial Institute from 1946 to 1977. The age ranged from 1 month to 57 years with a mean of 7.2 years and a median age of 5 years. An analysis of the survival results showed that patients continued to die of disease until 66 months post-diagnosis, making the 5-year survival a much better evaluation criterion for this group than the traditional 2-year survival. Males fared significantly better in this series (p less than 0.01). This was not due to detectable differences in age group, or histology. While the older age group (more than 15 years old) showed a somewhat better survival outlook for the first 2 years post-diagnosis, this difference became negligible at 5 years post-diagnosis.

Kinetoplast DNA and RNA of Trypanosoma brucei

Kinetoplast DNA (kDNA) and kinetoplast RNA (kRNA) were isolated from bloodstream and procyclic culture forms of two clonal strains of Trypanosoma brucei. No differences were observed in kDNA (maxicircle) restriction profiles between bloodstream or procyclic culture forms of the same strain. Some differences were observed in kDNA maxicircle restriction sites between the two strains. Buoyant density analysis of Pst I digested kDNA showed the release of a minor low density band representing unit length linearized maxicircle DNA. Pst I or Bam H1-linearized maxicircle DNA was isolated by the Hoechst 33258 dye--CsCl method and a restriction enzyme map of the maxicircle was constructed. Closed monomeric minicircles released from kDNA networks by sonication sedimented with a molecular size of around 1100 base pairs. A substantial minor length heterogeneity was evident in acrylamide gel electrophoresis of once cut minicircles. Several minicircle sequence classes and two Hind III maxicircle fragments representing approx. 50% of the maxicircle were cloned in the bacterial plasmid, pBR322, in Escherichia coli. A purified kinetoplast-mitochondrion fraction was isolated from procyclic culture forms by the Renografin flotation method. The major kRNA components were two small RNAs which comigrated with Leishmania tarentolae 9 and 12 S kRNAs in denaturing gels. These RNAs hybridized to the maxicircle component of the kDNA, specifically to the smaller cloned Hind III maxicircle fragment. This cloned fragment had substantial sequence homology with the cloned maxicircle fragment from L. tarentolae which contains the 9 and 12 S RNA genes, implying an evolutionary conservation of the 9 and 12 S gene sequences. Identical kRnAs were observed in cultured bloodstream forms of T. brucei.

Strains and clones of Trypanosoma cruzi can be characterized by pattern of restriction endonuclease products of kinetoplast DNA minicircles

A simple method was developed for the characterization of different strains of Trypanosoma cruzi. T. cruzi stocks isolated from vectors or by hemoculture from patients with Chagas disease could be grouped in subpopulations having similar patterns of restriction endonuclease products of kinetoplast DNA minicircles. We designate such subpopulations by the term "schizodemes." Furthermore, it is shown that, from a given T. cruzi strain, clones with different biological properties can be isolated and identified by their restriction patterns.

Characterization of pathogenic trypanosomatidae by restriction endonuclease fingerprinting of kinetoplast DNA minicircles

A simple protocol was developed for the routine preparation of a kinetoplast DNA fraction from trypanosomatids. The digestion of this DNA with selected restriction endonucleases, followed by the electrophoretic analysis of the fragments on polyacrylamide gradient gels, yielded characteristic patterns that could be used for the intrinsic characterization of stocks (populations derived by serial passage in vivo and/or in vitro from a primary isolation, without any implication of homogeneity or characterization), strains (sets of populations originating from a group of trypanosomes of a given species or subspecies present at a given time in a given host or culture, and defined by the possession of one or more designated characters), and clones (trypanosomes derived from a single individual by binary fission) of certain pathogenic hemoflagellates.

The kinetoplast DNA of the hemoflagellate protozoa

The kinetoplast DNA of Leishmania tarentolae and Trypanosoma brucei was studied in terms of genetic organization and transcriptional activity. Several minor sequence classes of minicircles from L. tarentolae were cloned in a bacterial plasmid and were compared in terms of sequence organization. The cloned minicircles were characterized by the possession of a constant region of at least 91 nucleotides and a variable region. Minicircles from Trypanosoma brucei strain 366D were also cloned. Fragments of the maxicircle DNA from both species were also cloned in pBR322. No homology with the cloned minicircles was apparent. Several maxicircle transcripts, in addition to the 9 and 12s presumptive ribosomal RNAs, were observed in L. tarentolae. The 9 and 12s RNA genes were also mapped on the T. brucei maxicircle. Sequence homology between the L. tarentolae 9 and 12s RNA genes and the T. brucei 9 and 12s RNA genes was observed. A culture system was developed to study the developmental change of cultured bloodstream forms of T. brucei into procyclic forms. This developmental system is amenable for the study of the role of the kinetoplast DNA in the extensive mitochondrial biogenesis that occurs at this time.

Evidence for a charge-shift electrochromic mechanism in a probe of membrane potential

Extrinsic optical probes have become important tools for monitoring membrane potential, with probes now available for many tissue or cell suspension systems. In each case that has been studied in detail, it seems that the mechanism involves a shift in the equilibrium population of the probe from one chemical environment to another in response to the transmembrane potential; the environments perturb the probe's spectrum differently. As this indirect mechanism involves a redistribution of dye between chemical environments that are likely to vary if a given probe is transferred from one membrane to another, a potential probe that is effective and calibrated for all membrane systems has not been realised. We present here evidence for a direct response of a probe chromophore to the electric field across membrane systems. The results suggest it might be possible to develop a universal set of membrane probes.

Restriction map, partial cloning and localization of 9S and 12S kinetoplast RNA genes on the maxicircle component of the kinetoplast DNA of Leishmania tarentolae

We have constructed a restriction map of the maxicircle component of the kinetoplast DNA of Leishmania tarentolae for the enzymes EcoRI, Bam HI, HaeIII, HpaII, SalI, BglII and HindIII. The 9 and 12S kinetoplast RNAs were localized on this map. Two fragments of this maxicircle molecule were cloned in the bacterial plasmid, pBR322, including a 4.4 . 10(6) dalton EcoRI/BamHI fragment which contains the 9 and 12S RNA genes.

Isolation of maxicircle component of kinetoplast DNA from hemoflagellate protozoa

Maxicircle DNA has been isolated from the kinetoplast DNA of Leishmania tarentolae culture forms by bouyant separation in CsCl in the presence of the A + T-binding dye Hoechst 33258, after liberation from the kinetoplast DNA network by cleavage with the single-hit restriction endonuclease EcoRI. The purified linearized maxicircle DNA has a density in CsCl of 1.681 g/cm3 (79% A + T) and a molecular weight of approximately 18-20 x 10(6). The maxicircle molecule exhibited intramolecular base composition heterogeneity ranging from 85% A + T to 74% A + T.

Kinetoplast RNA of Leishmania tarentolae

RNA has been isolated from highly purified kinetoplast-mitochondrial fractions of Leishmania tarentolae, and shown to consist of two major species that sediment at 9S and 12S in sucrose and also several additional low molecular weight species which were visualized by gel electrophoresis. The in vivo transcription of 9S and 12S RNAs was inhibited by ethidium bromide and rifampin, and was fairly insensitive to low actinomycin D and camptothecin. The 9S and 12S RNAs were isolated by acrylamide gel electrophoresis or by sedimentation in sucrose. Both RNAs contained approximately 80% A + U and did not contain long stretches of poly(A). The 9S and 12S RNAs were found to hybridize selectively to the maxicircle sequences of the kinetoplast DNA, implying that the maxicircle, and not the minicircle, represents the informational mitochondrial DNA in the kinetoplast.

Radiation treatment planning

Radiation treatment planning has developed into a substantial and effective component of the entire radiation treatment approach. Over the last 2 decades, with the development of high energy electron and x-ray sources, and also with the availability of new radionuclides and techniques for internally applied radiation, all of which permit a high degree of concentration of radiation, treatment planning has been developed to make best use of these modalities. The use of automatic computation has proved necessary in order to handle the large amounts of radiation data involved in treatment dose calculation. Tumor and anatomical localization has been carried out with increasing precision. Several cases are described which illustrate planning and in particular the use of computerized transverse tomography. The use of moving shadow-shields is also described. For internally applied radiation, the features of iodine-125 are illustrated.

Pulse-labeling of kinetoplast DNA: localization of 2 sites of synthesis within the networks and kinetics of labeling of closed minicircles

Short pulse-labeling of log phase Crithidia fasciculata cells with [3H]thymidine allowed the autoradiographic visualization of 2 sites of replication of kinetoplast DNA situated at the periphery of the networks and separated by 180 degrees. Longer pulse-labeling led to the previously reported total peripheral labeling pattern. Pulse-labeled networks possess an intermediate density in ethidium bromide-CsCl equilibrium gradients between the densities characteristic of closed networks and open or linear DNA. Removal of ethidium bromide by several methods and treatment of intermediate band networks with RNase and pronase had no effect on the equilibrium rebanding pattern. Closed minicircles of Leishmania tarentolae are not labeled by a short pulse of intact cells with [3H]thymidine. A chase of approximately 3-4 hr is required for the appearance of radioactivity in closed minicircles, a time delay which implies the existence of intermediate events between replication and eventual covalent closure of the minicircles.

Descending thoracic aortofemoral bypass for distal aortic reconstruction after removal of an infected dacron prosthesis

A simplified technique of descending thoracic aortofemoral bypass is presented. This technique was employed successfully in a patient in whom an infected aortofemoral Dacron bypass was removed and an axillofemoral reconstruction had failed.