Effective control of cisplatin induced emesis by combination drug regimen

Thirty two cycles of chemotherapy were administered to sixteen patient containing 50-75 mg/msq. of cisplatin. For antiemetic prophylaxis, each patient received metoclopramide alone in the first cycle and a combination of metoclopramide + dexamethasone + lyrazepam in the next cycle. Effective control of emesis was achieved in 81% cycles on the combination antiemetic regime as compared to 19% on MCP alone. There was no statistical difference in the relief of nausea by the two regimens.

Serum IgM rheumatoid factor by enzyme-linked immunosorbent assay (ELISA) delineates a subset of patients with deforming joint disease in seronegative juvenile rheumatoid arthritis

Using human IgG as an antigen in an enzyme-linked immunosorbent assay (ELISA), we looked for the presence of IgM rheumatoid factor (RF) in the sera of 74 children with juvenile rheumatoid arthritis (JRA). Nine children had RF detectable by both latex agglutination and ELISA. Forty-five percent (26 of 65) of the children who were seronegative by latex agglutination were found to be positive for IgM RF by ELISA. The prevalence of IgM RF was higher in patients with polyarticular onset disease (57.4%) than in those with pauciarticular onset (38.5%) or systemic onset (27.2%) disease. The prevalence of RF was higher in sera from patients with deforming joint disease than those without deformities (P < 0.01).

A novel ompC mutation of Escherichia coli K-12 that reduces OmpC and OmpF levels in the outer membrane

A novel ompC mutation was isolated that not only lowered the amount of its own product, OmpC27, but also reduced the level of OmpF present in the outer membrane. ompC27 codes for a mutant OmpC protein that contains two non-native cysteine residues. The ompC27 allele confers phage resistance by lowering the level of OmpC present in the outer membrane. This effect on OmpC27 was manifested at the level of assembly as a result of disulphide bond formation between the two cysteine residues. This disulphide bonding in OmpC27 also produced a novel phenotype by specifically influencing OmpF levels. The effect of OmpC27 on OmpF was partly a result of a lowering of ompF transcription, and partly a result of an effect at the post-transcription level. The transcriptional effect is likely to be brought about by a defective membrane as a result of the insertion of the disulphide bond containing OmpC27. The post-transcriptional effect of OmpC27 on OmpF could be due to interference at the assembly level. In a dsbA::kan1 background where the in vivo disulphide bonding ability was dramatically reduced, the OmpC27-mediated effects were also curtailed.

OmpF assembly mutants of Escherichia coli K-12: isolation, characterization, and suppressor analysis

This paper describes a novel genetic method used to isolate mutations that alter proper assembly of OmpF in the outer membrane. The thermolabile nature of assembly intermediates allowed selection of temperature-sensitive mutations within the ompF gene. A variant allele of ompF (ompF-Dex) was used because it provided a convenient selectable phenotype (Dex+). Assembly mutants were isolated in two steps. First, amber mutations were obtained that mapped in ompF-Dex. This resulted in a Dex- phenotype. Starting with these Dex- strains, Dex+ revertants were isolated. Mutants that displayed a temperature-sensitive Dex+ phenotype were further characterized. Three such mutants possessed a single substitution within ompF that reverted the nonsense codon to a sense codon which replaced W214 with either an E or Q and Y231 with a Q residue in the mature OmpF protein. All three mutant OmpF proteins showed an assembly defect. This defect led to a substantial reduction in the amount of stable OmpF trimers with the concomitant increase of a high-molecular-weight form of OmpF which migrated at the top of the gel. Suppressor mutations were sought that corrected the assembly defect of OmpF. These extragenic suppressor mutations were mapped at 45 min on the Escherichia coli chromosome. The suppressor mutations displayed no allele specificity and were recessive to the wild-type allele. In the presence of a suppressor, mutant stable trimers appeared in an almost normal manner. The appearance of stable trimers concurred with a substantial loss of the high-molecular-weight OmpF species. At this stage, it is not clear whether the high-molecular-weight species of OmpF is a normal assembly intermediate or a dead-end assembly product. The results presented in this study raise the intriguing possibility of a chaperone-like activity for the wild-type suppressor gene product.

Scleromyxoedema with features of systemic sclerosis

The case is described of a patient with scleromyxoedema with features typical of systemic sclerosis. The features were so characteristic that the disease was misdiagnosed as systemic sclerosis. A brief review of the association of the two diseases is given.

Arabidopsis Acetohydroxyacid Synthase Expressed in Escherichia coli Is Insensitive to the Feedback Inhibitors

Acetohydroxyacid synthase (AHAS), the first enzyme unique to the biosynthesis of isoleucine, leucine, and valine, is the target enzyme for several classes of herbicides. The AHAS gene from Arabidopsis thaliana, including the chloroplast transit peptide, was cloned into the bacterial expression plasmid pKK233-2. The resulting plasmid was used to transform an AHAS-deficient Escherichia coli strain MF2000. The growth of the MF2000 strain of E. coli was complemented by the functional expression of the Arabidopsis AHAS. The AHAS protein was processed to a molecular mass of 65 kilodaltons that was similar to the mature protein isolated from Arabidopsis seedlings. The AHAS activity extracted from the transformed E. coli cells was inhibited by imidazolinone and sulfonylurea herbicides. AHAS activity extracted from Arabidopsis is inhibited by valine and leucine; however, this activity was insensitive to these feedback inhibitors when extracted from the transformed E. coli.

Overexpression of Acetohydroxyacid Synthase from Arabidopsis as an Inducible Fusion Protein in Escherichia coli: Production of Polyclonal Antibodies, and Immunological Characterization of the Enzyme

Acetohydroxyacid synthase (AHAS, EC 4.1.3.18) is the first enzyme unique to the biosynthesis of valine, leucine, and isoleucine. This enzyme is the target site of several classes of structurally unrelated herbicides. The conventional method of antibody production using purified protein has not been successful with this enzyme. Two separate fragments of a gene encoding a portion of the mature region of AHAS from Arabidopsis were fused with the trpE gene from Escherichia coli using the pATH1 vector. E. coli cells transformed with each respective plasmid expressed a fusion protein at levels greater than 10% of the total cell protein. The fusion protein was purified and used to immunize rabbits. Antisera obtained from the immunized rabbits immunoprecipitated AHAS activity from Arabidopsis cell free extracts. The anti-AHAS antisera reacted with a 65 kilodalton protein band in electrophoretically resolved extracts of Arabidopsis. In cross-reactivity tests, this antibody was able to immunoprecipitate AHAS activity from various plant species. Furthermore, a protein band with a molecular mass of 65 kilodaltons was detected in the crude extracts of all plant species tested on a Western blot. These results indicate that the 65 kilodalton protein represents AHAS in various plant species. The wide spectrum of cross-reactivity for the antisera supports the view that the AHAS enzyme is highly conserved across all plant species.

A genetic approach for analyzing the pathway of LamB assembly into the outer membrane of Escherichia coli

Results presented in this study demonstrate that a mutation which inserts an additional tyrosine between the 2 tyrosines at residues 118 and 119 of mature LamB protein results in a temperature-dependent assembly defect. This defect leads to the accumulation of an intermediate at the restrictive temperature that is most likely an assembly-defective monomer. These monomers are rapidly degraded in the wild type (htrA+) strain, and the biphasic kinetics of this degradation indicate that the mutation affects the assembly process and not the final product, i.e. stable trimers. In addition, our data show that the temperature-dependent assembly defect in the mutant strain is reversible, and therefore the accumulated monomers represent a true assembly intermediate. Fractionation studies show that the monomers, which can be accumulated in htrA (degP) mutants at the restrictive temperature, are associated with the outer membrane, indicating that trimerization of LamB is not a prerequisite for localization.

Nur77 is differentially modified in PC12 cells upon membrane depolarization and growth factor treatment

The rat pheochromocytoma cell line PC12 can be induced by growth factors to undergo proliferation and neuronal differentiation. These cells also have excitable membranes that can be depolarized by neurotransmitters or elevated levels of extracellular KCl. Treatment of PC12 cells with growth factors or membrane-depolarizing agents rapidly activates the expression of specific genes whose products are thought to mediate the subsequent biological responses. One such gene, nur77, is a member of the steroid and thyroid hormone receptor gene superfamily. We have identified the Nur77 protein and shown that it is synthesized rapidly and transiently in PC12 cells following stimulation, has a short half-life of 30 to 40 min, and is located in both the nucleus and the cytoplasm. Nur77 is posttranslationally modified, primarily by phosphorylation on serine residues. Phosphopeptide analysis reveals that Nur77 is modified differently upon membrane depolarization than after treatment with growth factors. We hypothesize that the activity of Nur77 is regulated by both differential gene expression and posttranslational modification and that these modes of regulation contribute to distinct downstream responses specific to membrane depolarization and growth factor treatment.

Occurrence of systemic autoimmune disorders & autoantibodies in house-hold contacts of patients with systemic lupus erythematosus

Household contacts of 22 randomly selected patients with systemic lupus erythematosus (SLE) were screened for autoimmune diseases and autoantibodies. Thirty nine consanguineous and 17 nonconsanguineous household contacts were studied. In the first group symptomatic SLE was seen in 5 per cent, rheumatoid arthritis in 2.5 per cent, antinuclear antibody (ANA) in 10 per cent and rheumatoid factor (RF) in 5 per cent while anti-dsDNA, anti-nRNP and anti-Sm antibodies were not detected in any individual. The second group showed total absence of any marker of autoimmunity. In normal controls only RF was detected in 3 per cent. The occurrence of markers of autoimmunity only in consanguineous household contacts of patients with SLE further confirms the recognised role of genetic factors in the etiology of SLE.

Effects of commonly used NSAID's on gastric mucosa. A clinico-endoscopic and histopathological study

Non steroidal anti-inflammatory drugs (NSAID's) are one of the most commonly used agents in clinical practice today. All these drugs are known to produce gastro-intestinal lesions. In the present study we found that aspirin, indomethacin and phenylbutazone caused gastric mucosal damage in 90.9%, 100%, respectively while ibuprofen and paracetamol caused gastric mucosal damage in 33.3% and 37.5% respectively. Thus latter two drugs were safer NSAID's. Further more we have demonstrated that endoscopic monitoring of the patients on NSAID's is a sensitive method of early detection of gastric mucosal damage. This monitoring may be particularly valuable in high risk subjects on NSAID's.

Effects of commonly used non steroidal anti-inflammatory drugs on gastric mucosa. A clinical, endoscopic and histopathological study

Non steroidal anti-inflammatory drugs (NSAIDS) are known to produce gastro-intestinal lesions. In the present work we found that aspirin, indomethacin and oxyphenbutazone caused gastric mucosal damage in 90.9%, 100% and 100% respectively, while ibuprofen and paracetamol caused damage in 33.3% and 37.5% of cases respectively. Thus the latter two drugs were much safer NSAIDs. Furthermore we demonstrated that endoscopic monitoring of patients on NSAIDs is a sensitive method for early detection of gastric mucosal damage. This monitoring may be particularly valuable in high risk subjects on NSAIDs.

Platelet ionic calcium and serum total calcium in essential hypertension

A total of 44 cases comprising hypertensive (31) and normotensive group (13) were studied. Serum total calcium concentrations remained unaltered in hypertensives. Platelet cytosolic calcium in hypertensive group was significantly higher as compared to the normotensive controls. Platelet cytosolic calcium correlated with systolic and diastolic blood pressure and mean arterial pressure significantly.

Brainstem auditory evoked potentials (BAEPs) in pregnant women

The electrophysiological correlate of change in sensory function during pregnancy has not been reported. The brain stem auditory evoked potentials were recorded in eight pregnant women during third trimester from CZ-A1 and CZ-A2 position, with alternating 90 dB sound pressure click stimuli delivered at 10/sec and -40 dB (white noise) masking of contralateral ear. Two thousand and forty eight responses were analysed and replicated. The noise and other artefacts were rejected with filter bandpass setting 150 to 3000 Hz. The evoked responses in pregnant women were compared with ten age matched normal subjects using Student's 't' test. The threshold for eliciting wave V of the brainstem auditory response was higher in pregnant women (28.1 +/- 2.1 dB). The absolute peak latencies of waves I to V were similar in both groups. However, Inter peak latencies (IPLs) I-III, III-V were on higher side in the pregnant women, and I-V, in particular (3.9 +/- 0.14) was significantly higher when compared with controls (3.73 +/- 0.16). These findings suggest that besides an increase in evoking wave V threshold, neural conduction process in brainstem auditory pathways during pregnancy is also delayed within + 2SD of the mean central conduction time in nonpregnant state.

Recombination mediates production of an extrachromosomal circular DNA containing a transposon-like human element, THE-1

An abundant class of HeLa extrachromosomal circular DNA containing the transposon-like element, THE-1, is shown to arise via site specific recombination. The chromosomal locus from which these circles are derived, however, is single-copy. Northern blot analysis detects homology to two polyadenylated RNAs in HeLa cells. The possible presence of an origin of replication and its role in generating these small polydisperse circles is discussed.

A novel mutation, cog, which results in production of a new porin protein (OmpG) of Escherichia coli K-12

A mutant of Escherichia coli K-12 which produces a new outer membrane protein, OmpG, was isolated and genetically and biochemically characterized. The presence of OmpG allows growth on maltodextrins in the absence of the LamB maltoporin. The data obtained from in vivo growth and uptake experiments suggested that the presence of the OmpG protein results in an increase in outer membrane permeability for small hydrophilic compounds. In light of these findings, we suggest that OmpG is a porinlike protein. The mutation which results in the expression of OmpG has been termed cog (for control of OmpG) and mapped to 29 min on the E. coli chromosome. Diploid analysis shows that the mutant cog-192 allele is recessive for both the Dex+ and OmpG+ phenotypes. We propose that the cog mutation destroys a negative regulatory function and therefore derepresses ompG expression.

Ultrastructural changes in parietal cells in iron deficiency anemia

Eighteen patients with iron deficiency anemia (IDA) and 14 age and sex matched control subjects were studied with regard to ultrastructural changes in parietal cells. The control subjects had normal hemoglobin and serum iron levels and endoscopic examination of the upper gastrointestinal tract. Thirteen cases of iron deficiency anemia had chronic superficial gastritis on light microscopy. Ultrastructural abnormalities in the parietal cells, such as indented or pyknotic nucleus with irregular outline, grossly distorted canalicular system, abnormal large empty spaces in the cytoplasm and paucity of mitochondria, were demonstrated in all IDA patients but not in controls. The presence of superficial gastritis and ultrastructural changes were not related either to hemoglobin or serum iron levels in the IDA group.

Identification and characterization of a new gene of Escherichia coli K-12 involved in outer membrane permeability

Using a genetic selection for mutations which allow large maltodextrins to cross the outer membrane of Escherichia coli in the absence of the LamB maltoporin, we have obtained and characterized two mutations that define a new locus of E. coli. We have designated this locus imp for increased membrane permeability. Mapping studies show that the imp gene resides at approximately 1.2 min on the E. coli chromosome. The mutations alter the permeability of the outer membrane resulting in increased sensitivity to detergents, antibiotics and dyes. The mutations are nonreverting and codominant. Genetic analysis of the mutations suggest that the imp gene is an essential gene. We describe a general cloning strategy that can be used to clone both dominant and recessive alleles. Using this technique, we have cloned the wild-type and mutant imp alleles onto a low copy number plasmid.

Platelet serotonergic mechanisms and glomerulonephritis

Proven cases (28) of glomerulonephritis (GN) were evaluated for clinico-biochemical profile, bleeding time, platelet count, platelet aggregation and platelet serotonergic mechanisms. Inordinate increase in platelet aggregation and altered platelet serotonergic mechanisms (reduced 5-HT, uptake, reduced intraplatelet 5-HT and increased plasma 5-HT) were demonstrated in some histopathological types of GN. The mechanisms and importance of these alterations have been discussed.

Cancer cervix complicating pregnancy: a case report

A case of invasive carcinoma cervix in a 25 years woman complicating labour is presented with brief review of literature.

Detection of multiple, novel reverse transcriptase coding sequences in human nucleic acids: relation to primate retroviruses

A variety of chemically synthesized oligonucleotides designed on the basis of amino acid and/or nucleotide sequence data were used to detect a large number of novel reverse transcriptase coding sequences in human and mouse DNAs. Procedures involving Southern blotting, library screening, and the polymerase chain reaction were all used to detect such sequences; the polymerase chain reaction was the most rapid and productive approach. In the polymerase chain reaction, oligonucleotide mixtures based on consensus sequence homologies to reverse transcriptase coding sequences and unique oligonucleotides containing perfect homology to the coding sequences of human T-cell leukemia virus types I and II were both effective in amplifying reverse transcriptase-related DNA. It is shown that human DNA contains a wide spectrum of retrovirus-related reverse transcriptase coding sequences, including some that are clearly related to human T-cell leukemia virus types I and II, some that are related to the L-1 family of long interspersed nucleotide sequences, and others that are related to previously described human endogenous proviral DNAs. In addition, human T-cell leukemia virus type I-related sequences appear to be transcribed in both normal human T cells and in a cell line derived from a human teratocarcinoma.

Anti-cardiolipin antibodies in infectious mononucleosis react with the membrane of activated lymphocytes

To elucidate the mechanisms of autoantibody induction in infectious mononucleosis (IM), we have studied sera from 35 patients with IM with enzyme-linked immunosorbent assays using purified antigens. In the IM group 37% had IgM antibodies to cardiolipin above the normal range (mean plus 2 standard deviations of control sera). Significantly elevated frequencies of antibodies to actin (26%) and cytoskeletal antigens (97% versus 29% in normal sera) were also found, but levels of IgM rheumatoid factors, IgM antibodies to single-stranded DNA and antibodies to ribonucleoproteins (nRNP/Sm, Sm and La) were normal. Affinity purified anti-cardiolipin antibodies reacted with the cell membrane of transformed lymphocytes but not with resting cells, suggesting that cell activation was required for the expression of antigenic epitopes. Our data suggest that the autoantibody response in IM is restricted to two classes of autoantigens: cytoskeletal and cell membrane antigens. The appearance of antigenic epitopes on EBV-transformed lymphocytes could be a mechanism for the generation of anti-cardiolipin antibodies in infectious mononucleosis. Similar mechanisms could operate in autoimmune rheumatic disease.

Acceleration of growth rate in growth hormone-deficient children treated with human growth hormone-releasing hormone

Twenty-four growth hormone-deficient children were treated with growth hormone releasing hormone-40 (GHRH) for 6 months or longer. GHRH (1 to 4 micrograms/kg of body weight per dose) was administered subcutaneously every 3 h (n = 10); or every 3 h overnight only (n = 10); or by twice daily injections (n = 4). Twenty-one children had an increase in growth rate during GHRH treatment. The growth velocities (mean +/- SD; cm/yr) before and during treatment were, respectively: every 3 h 3.5 +/- 1.4 versus 10.0 +/- 2.2, p = 0.0001; overnight only 3.4 +/- 1.0 versus 6.2 +/- 2.1, p = 0.008; twice daily injections 3.2 +/- 1.8 versus 7.9 +/- 2.4, p = 0.06. Using these three modes of GHRH administration, different total daily amounts of GHRH were administered. Regression analysis of average daily dose versus growth velocity revealed a correlation coefficient (r) value of 0.57, p = 0.004. Sixteen children received extended treatment for periods varying from 9 to 30 months. Of these, seven children were treated continuously for 9 months with pump overnight only and 5 for 12 months with pump every 3 h. Their growth velocities were sustained at a similar rate as those observed at 6 months. Six children received both twice daily and three hourly treatments consecutively. The growth velocities were similar during both treatments. Eleven children developed circulating antibodies to GHRH during treatment, however, all 11 had accelerated growth rates during GHRH therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic identification of the pore domain of the OmpC porin of Escherichia coli K-12

We have isolated and characterized 31 mutations in the ompC gene which allow Escherichia coli to grow on maltotriose (Dex+) in the absence of the LamB and OmpF porins. These ompC(Dex) mutations include single-base-pair substitutions, small deletions, and small insertions. DNA sequence analysis shows that all of the alterations occur within the coding region for the first 110 amino acids of mature OmpC. The 26 independent point mutations repeatedly and exclusively alter residues R37, R74, and D105 of mature OmpC. In each case, a charged amino acid is changed to an uncharged residue. Biochemical and physiological tests suggest that these alterations increase the size of the pore channel. Starting with three different ompC(Dex) strains with alterations affecting R74, we isolated mutants that could grow on maltohexose (Hex+). These mutants each contained a second alteration in the ompC gene involving residues R37, D105, or R124. The combined effects on pore function of the two mutations appear to be additive. These experiments suggest that we have identified the important residues of OmpC peptide involved in pore function. On the basis of these mutations and general rules for membrane protein folding, a model for the topology of the OmpC protein is proposed.

Isolation and characterization of OmpC porin mutants with altered pore properties

The LamB protein is normally required for the uptake of maltodextrins. Starting with a LamB- OmpF- strain, we have isolated mutants that will grow on maltodextrins. The mutation conferring the Dex+ phenotype in the majority of these mutants has been mapped to the ompC locus. These mutants, unlike LamB- OmpF- strains, grew on maltotriose and maltotetraose, but not on maltopentaose, and showed a significantly higher rate of [14C]maltose uptake than the parent strain did. In addition, these mutants showed increased sensitivity to certain beta-lactam antibiotics and sodium dodecyl sulfate, but did not exhibit an increase in sensitivity to other antibiotics and detergents. The nucleotide sequence of these mutants has been determined. In all cases, residue 74 (arginine) of the mature OmpC protein was affected. The results suggest that this region of the OmpC protein is involved in the pore domain and that the alterations lead to an increased pore size.

Role of micF in the tolC-mediated regulation of OmpF, a major outer membrane protein of Escherichia coli K-12

Mutation in the tolC locus greatly reduces normal synthesis of OmpF, a major porin protein of Escherichia coli K-12. Experiments that use ompF-ompC chimeric genes demonstrate that a tolC mutation exerts its effect at either the promoter or the amino-terminal end of the ompF gene. Direct analysis of ompF mRNA from tolC+ and tolC strains showed that the amount of ompF transcript in the latter was greatly reduced. We have also observed that, in addition to reducing the amount of OmpF, a tolC mutation increases the level of OmpC protein to a much greater extent than occurs in an OmpF mutant and also increases micF RNA synthesis as shown by increased beta-galactosidase synthesis in a micF-lacZ fusion strain. Based on these observations, we suggest that an increased expression of the micF gene in a tolC mutant results in the reduced expression of ompF and that a major effect of the tolC mutation may be to push the porin-regulating system to favor ompC and micF to a greater extent than under high-osmolarity conditions.

Analysis of epidermal proteins for DNA-binding activity

A group of DNA-binding proteins from the soluble extract of newborn rat epidermis have been separated by chromatography using DNA-cellulose columns. The electrophoretogram of the DNA-binding proteins eluted from a single stranded DNA-cellulose column shows five major proteins of molecular weights ranging between 25K to 40K. Both the epidermal protein filaggrin and most keratins, except two high molecular weight keratins, do not show in vitro DNA-binding activity.

Cloned extrachromosomal circular DNA copies of the human transposable element THE-1 are related predominantly to a single type of family member

The 2300 base-pair transposon-like human element, THE-1, has been identified in the extrachromosomal circular DNA of the established human cell line HeLa as a relatively homogeneous population of covalently closed 1900 base-pair molecules. THE-1, which has been classified tentatively as a retroviral-like transposable element (a retrotransposon), is present in the extrachromosomal circular DNA of African green monkey (BSC-1) and human lymphoblastoid (Jurkat) cell lines. The 1900 base-pair extrachromosomal elements isolated and cloned from HeLa cells (1) appear to contain only THE-1-specific nucleotide sequences, (2) are circularized versions of the linear chromosomal sequence, and (3) are related predominantly to a single, or single type of, family member.

Structure of fredericamycin A, an antitumor antibiotic of a novel skeletal type; spectroscopic and mass spectral characterization

IR, UV-visible spectroscopy, circular dichroism, 1H and 13C NMR studies, high resolution electron impact, field desorption, and fast atom bombardment mass spectral studies are reported for fredericamycin A (NSC-305263), a novel antitumor antibiotic of acid-base indicator type produced by Streptomyces griseus (FCRC-48). The spectral data are correlated with the structure obtained by X-ray crystallography as (E,E)-6',7'-dihydro-4,9,9'-trihydroxy-6-methoxy-3'-(1,3-pentadienyl++ +)-spiro- [2H-benz[f]indene-2,8'-[8H]-cyclopent-[g]-isoquinoline]-1,1', 3,5,8(2'H)-pentone. The novel spiro ring antibiotic exhibits unusual 1H and 13C NMR spectroscopic and chemical behavior, not previously observed in other antibiotic structures.

Magnetic resonance studies of fredericamycin A: evidence for O2-dependent free-radical formation

Fredericamycin A, a newly described potent antitumor antibiotic, exhibits unusual spectroscopic and physical properties. The drug shows a striking color change from red to blue on exposure to O2, with the appearance of an optical absorption band at 675 nm; on addition of acid these changes are readily reversed. 1H and 13C NMR spectra of fredericamycin A show that the resonances from the quininoid half of the molecule disappear after exposure to O2 but reappear on acidification in parallel with the observed optical spectral shift. These unusual NMR data are explained by electron spin resonance studies which demonstrate that fredericamycin A spontaneously forms an oxidized free radical with electron transfer to O2. The observed hyperfine structure of this radical is consistent with one-electron oxidation of the quininoid group. After fredericamycin A is exposed to O2, an EPR signal is observed with axial symmetry with temperature and power saturation behavior suggestive of .O2-. Spin-trapping EPR studies demonstrate that the drug reduces O2 to .O2- and H2O2 to .OH. This spontaneous mechanism of O2 reduction with the generation of oxidized drug free radicals and reduced oxygen free radicals is unprecedented among anticancer drugs, suggesting that fredericamycin A could be the forerunner of a new class of anticancer drug.

Systemic lupus erythematosus in North Indian Asians. A prospective analysis of clinical and immunological features

One hundred and one patients with systemic lupus erythematosus (SLE) from North Indian stock are presented. The clinical manifestations, laboratory parameters, causes of death, and survival are compared and contrasted with the other major reported series. SLE of North Indian Asians has several features comparable to those reported from the West, but other features are more similar to the SLE seen in Mongoloid races.

Extrachromosomal DNA in eucaryotes

Eucaryotic extrachromosomal DNAs have been organized into four major classes: (1) Organelle DNAs, (2) plasmid DNAs, (3) amplified genes, and (4) intermediates and/or by-products of DNA transpositions and rearrangements. In this review some of the relatively well-characterized members of each class are described; it is suggested that many of them reflect the complexity and plasticity of eucaryotic genomes.