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Biomedical subjects

L Grossman

Publications and source records attributed to L Grossman.

At least 109 records · Page 6Linked to original sources
PubMed1983

Purification and characterization of DNase VIII. A 5'-3' directed exonuclease from human placental nuclei.

DNase VIII is an exonuclease purified from human placenta trophoblast nuclei. The enzyme has a pH optimum of 9.5 and requires a divalent cation. It is inhibited by salt and stimulated by Triton X-100. Glycerol gradient analysis of the activity indicates a sedimentation coefficient of 2.8 S (31,000 daltons if globular). This enzyme initiates hydrolysis from 5'-phosphorylated termini of single-stranded DNA and acts at internal phosphodiester bonds liberating 5'-phosphorylated oligonucleotides. It degrades polynucleotides of repeating base sequence as well as single-stranded DNA, yielding oligonucleotides of even number, in which the main reaction products are dinucleotides. The activity on denatured DNA is not inhibited by the presence of ultraviolet-induced photoproducts. DNase VIII can also initiate hydrolysis at those distorted termini produced by the action of Micrococcus luteus dimer specific endonuclease on duplex DNA, which contains cyclobutane dimers.

Cell Nucleus↗
PubMed1983

Clinical evaluation of a flat-plate membrane plasma exchange system.

A new flat-plate membrane plasma separation system specifically designed for therapeutic plasma exchange (TPE) was clinically evaluated in both research and routine clinical settings. The study included a comparison to a currently available centrifugal cell separation system employed for TPE. A total of 267 membrane procedures were performed on 39 patients over a 14-month period. Both qualitative and quantitative studies showed that membrane plasma exchange procedures were equivalent to centrifugal procedures in the removal of plasma constituents from patients. A notable difference between the two types of procedure was the effect on the peripheral blood platelet count: the plasma filtrate from the membrane system was essentially cell-free and platelet counts fell only 11% during the procedure, compared to a 53% decrease during the centrifugation runs. Patient responses to both types of procedure were similar and the frequency of side-effects was low. A sampling of patient opinion revealed a preference for the membrane system for a variety of reasons. Procedure times were shorter with the membrane system because of higher achievable blood flow rates, and thus higher plasma exchange rates, while the overall nursing time requirement was lower. The results show that this flat-plate membrane TPE system enables rapid and effective plasma exchange therapy, and offered a number of monitoring and control functions that provided a safer, more efficient therapeutic procedure in the majority of patient treatments performed in this study.

Adult↗
PubMed1983

Central nervous system toxicity of high-dose cytosine arabinoside.

Ten patients with refractory acute leukemia were treated with high-dose cytosine arabinoside (Ara-C) infusions. Nine patients had previously achieved at least one complete remission using standard chemotherapy protocols that include cytosine arabinoside. Eight of the ten had been on maintenance therapy. Twelve courses of treatment were given, with the cytosine arabinoside infused over 1-2 hours in a dose of 3 gm/m2. Each course consisted of 12 to 16 doses given at 12-hour intervals. The drug was generally well tolerated but five patients developed central nervous system symptoms characterized by ataxia, dysphasia, nystagmus, dysdiadochokinesis, and a decreased level of consciousness. These changes began 3 to 34 days after the initiation of therapy and were severe at the time of death in two of the patients. One complete and one partial remission, lasting 2.5 months and 1 month, respectively, were documented. This experience suggests that high-dose Ara-C is of limited usefulness in refractory acute leukemia and may be frequently associated with significant neurotoxicity.

Acute Disease↗
PubMed1983

Enzymatic properties of purified Escherichia coli uvrABC proteins.

The cloned uvrA and uvrB genes of Escherichia coli K-12 were amplified by linkage to the PL promoter of plasmid pKC30. The uvrC gene was amplified in the high-copy-number plasmid pRLM 24. The three gene products (purified in each case to greater than 95% purity) and ATP are required to effectively incise UV-damaged DNAs. The uvrABC proteins bind tightly to damaged sites in DNA, requiring the initial attachment of the uvrA protein in the presence of ATP before productive binding of the uvrB and uvrC proteins. Using a cloned tandem double insert of the lac p-o region as a damaged DNA substrate for the uvrABC complex and analyzing the incision both 5' and 3' to each pyrimidine dimer, we found that one break occurs 7 nucleotides 5' to a pyrimidine dimer and a second break is made 3-4 nucleotides 3' from the same pair of pyrimidines in the dimer. No such breaks are found in the strand complementary to the dimer. The size of the incised fragment in the DNA suggests that incision may be coordinated with excision reactions in repair processes.

Bacterial Proteins↗
PubMed1983

Prospective randomized trial of piperacillin monotherapy versus carboxypenicillin-aminoglycoside combination regimens in the empirical treatment of serious bacterial infections.

Piperacillin as a single agent was compared in a prospective randomized trial with carboxypenicillin-aminoglycoside combinations in empirical therapy of serious bacterial infections. The difference in the clinical response rates with piperacillin (77% of 26 infection episodes) and combination therapy (75% of 24 infection episodes) were not statistically significant. Fewer adverse effects occurred in the piperacillin-treated group (42%) than in the combination-treated group (71%) (P = 0.0399 by Fisher's exact test), although neither nephrotoxicity nor hypokalemia alone was significantly less frequent in patients receiving piperacillin. However, the emergence of resistant organisms during therapy was more frequent among patients receiving piperacillin alone (42% of patients) than among patients receiving combination therapy (17% of patients) (P = 0.465 by Fisher's exact test). Moreover, emergence of resistance accounted for 5 of 9 patients with treatment failure, superinfection, or both when piperacillin was used as a single agent, compared with 2 of 10 similar patients in the combination group (P = 0.1299 by Fisher's exact test). The use of piperacillin as a single agent in the treatment of serious bacterial infections is not advocated, and the addition of an aminoglycoside to prevent emergence of resistance during empirical therapy of such infections is strongly recommended.

Adult↗
PubMed1983

Lactic acidosis in a patient with acute leukemia.

Lactic acidosis is a rare but potentially fatal complication of acute leukemia. The terminal phase of acute leukemia in a 22-year-old woman, heralded by lactic acidosis, is described in order to focus attention on the occurrence of this metabolic disturbance in the absence of overt manifestations of acute leukemia. As reported in other cases, the lactic acidosis in our patient responded poorly to bicarbonate therapy but dramatically to antileukemic chemotherapy. The pathogenesis of the lactic acidosis is unclear but it may be the result of an undefined 'paraneoplastic' metabolic disturbance induced by the leukemic cells.

Acidosis↗
PubMed1982

Human placental apurinic/apyrimidinic endonuclease. Mechanism of action.

The mechanism of action of the homogeneous preparation of human placental apurinic/apyrimidinic (AP) endonuclease, described in the previous paper (Shaper, N. L., Grafstrom, R. H., and Grossman, L. (1982) J. Biol. Chem. 257, 13455-13458), has been investigated in detail. This enzyme cleaves apyrimidinic DNA both 5' and 3' to the site of damage in a ratio of 60:40, respectively. Even though this enzyme can cleave on both sides of an internal AP site, it does not release deoxyribose 5-phosphate from terminal AP sites. However, a compound, tentatively identified as alpha, beta unsaturated deoxyribose 5-phosphate, is nonenzymatically released only from 5'-terminal AP sites, presumably by a beta-elimination mechanism.

DNA Glycosylases↗
PubMed1982

Human placental apurinic/apyrimidinic endonuclease. Its isolation and characterization.

An endonuclease from human placenta has been purified to apparent homogeneity, which acts specifically on DNA containing either apurinic or apyrimidinic sites. The isolation procedure, which results in a 20,000-fold purification and an overall yield of 15%, employs chromatography on a gel of octyl succinic anhydride coupled to agarose by diaminohexane spacers, isoelectric focusing, Sephadex G-75 chromatography, and DNA agarose affinity chromatography. Under conditions in which proteolysis is minimized, this enzyme appears to be the major species of apurinic/apyrimidinic endonuclease. The endonuclease is a monomeric protein with an apparent Mr = 37,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme has a pI of 7.4-7.6, requires Mg2+, is partially stimulated by Mn2+, and is inhibited by EDTA. It has no detectable exonuclease or phosphomonoesterase activity.

DNA-(Apurinic or Apyrimidinic Site) Lyase↗
PubMed1982

Enzymatic repair of pyrimidine dimer-containing DNA. A 5' dimer DNA glycosylase: 3'-apyrimidinic endonuclease mechanism from Micrococcus luteus.

A pyrimidine dimer-DNA glycosylase has been purified 20,000-fold from Micrococcus luteus. The enzyme is a single polypeptide chain with Mr = 18,000 that acts specifically on pyrimidine dimers, preferring those in double-stranded DNA to those in single-stranded DNA. The glycosylase cleaves the 5' residue of a pyrimidine dimer generating an apyrimidinic site and a mixed pyrimidine/pyrimidine nucleotide dimer. Under conditions of substrate excess, dimers containing a 5'-thymine are preferred to those with a 5'-cytosine residue. The glycosylase has an associated apyrimidinic/apurinic (AP) endonuclease that prefers apyrimidinic sites at the site of glycosylase action to either apurinic or apyrimidinic residues. This endonuclease is a Class I AP endonuclease in that it cleaves 3' to the AP site generating a 3'-deoxyribose moiety and a 5'-phosphate.

DNA Glycosylases↗
PubMed1982

Iontophoretic injections of kainic acid into the rat lateral hypothalamus: effects on ingestive behavior.

Iontophoretic injections of kainic acid into the dorsolateral hypothalamus of rats resulted in localized, partial depletions of neurons from the area without significant damage to adjacent areas of the diencephalon, including the zona incerta, dorsomedial hypothalamus and anterior as well as posterior regions of the hypothalamus that have been reported to be severely affected by mechanical injections of KA into the LH. Distant KA-sensitive structures such as the hippocampus and temporal lobe also showed no discernible neuronal loss or glial proliferation. The neuronal loss within the LH was far less severe after iontophoretic injections than after mechanical injections of KA. Our KA treated animals nonetheless displayed transient aphagia and adipsia, followed by variable periods of hypophagia and hypodipsia. After recovery of essentially normal ad lib feeding, the KA-treated rats failed to eat in response to a glucoprivic challenge (2-deoxy-D-glucose) but consumed normal quantities of water during periods of food deprivation. Their drinking response to hypertonic saline was somewhat reduced during the first hour after the treatment but normal at 6 as well as 24 hours. Unilateral KA injections produced only transient changes in ad lib food intake.

Animals↗
PubMed1982

Amplification of the uvrA gene product of Escherichia coli to 7% of cellular protein by linkage to the pL promoter of pKC30.

We have constructed a hybrid pKC30-uvrA plasmid (pGHY5003) in which transcription of the uvrA gene can be induced under pL control to amplify the uvrA gene product to 7% of cellular protein. To construct pGHY5003, we developed a genetic selection using the basal level of expression (30 degrees C) from pL in thermosensitive cI857 lysogens to isolate appropriately tailored repair genes inserted at the Hpa I site of pKC30 from recombinant DNA mixtures with a variety of products. In addition, a post-UV-irradiation radiolabeling method was adapted to screen inserts for temperature-inducible polypeptide synthesis directed by transcription under pL control rapidly. This should prove generally useful for isolating genes inserted at the Hpa I site of plasmid pKC30 with the following characteristics: (i) genetically functional hybrid plasmids selected from a large population of exonucleolytically tailored fragments ligated into Hpa I of pKC30 and (ii) production of high-level amplification for the gene product of interest by screening for post-UV-irradiation temperature inducibility of polypeptides synthesized from hybrid plasmids. The level of amplification obtained for the uvrA gene product from pGHY5003 is approximately 10,000-fold higher than estimates of the level of uvrA protein in logarithmic phase Escherichia coli.

Bacterial Proteins↗
PubMed1981

Purification and characterization of DNase VII, a 3' leads to 5'-directed exonuclease from human placenta.

An exonuclease, DNase VII, has been purified 6000-fold from human placenta. The enzyme has an apparent molecular weight of 43,000, requires Mg2+ for activity, and has a pH optimum of 7.8. The enzyme hydrolyzes single-stranded and nicked duplex DNA at the same rate proceeding in a 3' leads to 5' direction liberating 5'-mononucleotides. It does not measurably hydrolyze polyribonucleotides.

Deoxyribonucleases↗
PubMed1981

Histone reactivity of drug-induced antinuclear antibodies. A comparison of symptomatic and asymptomatic patients.

Anti-histone antibodies were measured in a group of patients with drug-induced lupus erythematosus and in asymptomatic patients with drug-induced antinuclear antibodies (DANA). Anti-histone antibodies were found in the majority of drug-induced lupus patients. DANA patients had lower titers of ANA and no detectable anti-histone activity. Longitudinal studies of the drug-induced lupus patients showed a gradual fall in the ANA and anti-histone titers. Our data suggest that the immune response in the drug-induced lupus patients is similar to but more intense than that seen in the DANA patients. Possible factors altering the immune response in these 2 groups are discussed.

Adolescent↗