A time for restraint.

The debate on the use of human embryos for research will be one of the more important issues of the 21st century. Unlike recombinant DNA technology, embryonic stem cell research most probably will result in the destruction of living embryos. Many people consider this research immoral, illegal, and unnecessary. Therefore, it is imperative to proceed cautiously. Federal funding of research using human embryos or pluripotent cells derived from them would be inappropriate until further resolution of the ethical issues has been achieved.

Deoxyribonucleic acid antibody: a method to detect its primary interaction with deoxyribonucleic acid.

Antibody to DNA in human serums can be detected by the ammonium sulfate method. This sensitive and specific technique, which measures the primary interaction between DNA and antibody to DNA, is based on the observation that free DNA is soluble in 50-percent saturated ammonium sulfate whereas antibody-bound DNA is insoluble.

The effect of carbohydrate depletion on procoagulant activity and in vivo survival of highly purified human factor VIII.

Human factor VIII procoagulant protein (factor VIII) was purified using a modification of our previously described method, in which Sephacryl S-400 elution, rather than QAE-cellulose chromatography, served as the final purification step. The protein had a specific activity of more than 2500 U/mg and consisted of a single polypeptide (Mr 100 000) when analyzed by SDS-polyacrylamide gel electrophoresis. Factor VIII was shown to be a glycoprotein by staining with periodic acid-Schiff's reagent following electrophoresis. Treatment of factor VIII with a mixture of exo- and endoglycosidases caused a reduction by about 50% in the intensity of periodic acid-Schiff staining, as determined by scanning densitometry, and an increase in electrophoretic mobility (equivalent to a new Mr 95 000). Removal of this portion of the total carbohydrate had no significant effect on factor VIII clotting activity or on thrombin potentiation of clotting activity. The in vivo survival curves of a native and sugar-depleted 125I-labeled factor VIII both showed similar patterns of initial rapid decay to 60 and 40% activity, respectively, followed by a one-half decay time of 4 h for both. These results suggest that the carbohydrate portion of human factor VIII does not contribute significantly to either clotting function in vitro or to biological turnover in vivo.

Aerosolized pentamidine. Approved for HIV-infected individuals at high risk for Pneumocystis carinii pneumonia.

Aerosolized pentamidine isethionate (NebuPent, LyphoMed Inc, Rosemont, Ill) was recently approved by the US Food and Drug Administration for use in prophylaxis against Pneumocystis carinii pneumonia in individuals infected with the human immunodeficiency virus who are at high risk for this infection. The recommended dose is 300 mg of aerosolized pentamidine isethionate administered every 4 weeks via the Respirgard II nebulizer (Marquest Medical Products Inc, Englewood, Colo). The drug is indicated for individuals infected with the human immunodeficiency virus who have a history of P carinii pneumonia or individuals with a CD4 (T4) lymphocyte count less than or equal to 0.2 x 10(9)/L with no history of P carinii pneumonia. We present information about the drug and its use, including safety information and use of the nebulizer.

Restriction-fragment map of the temperate Bacillus subtilis bacteriophage SPO2.

The endonucleases BglI, BglII, EcoRI, SalI, SmaI, and XbaI were used to fragment the phage SPO2 DNA. Electrophoretic analysis using ethidiumbromide agarose gels showed the phage to have nine BglI sites, one BglII site, four EcoRI sites, one SalI site, one SmaI site, and six XbaI sites. Using partial digestions, multiple endonuclease digestion, and autoradiography the fragments were sized and ordered into a circular map of 23 Md. Such an analysis locates the endonuclease sites, indicates which endonucleases are potentially useful in cloning with SPO2, and allows insertions and/or deletions in the SPO2 DNA to be characterized.

Isolation and characterization of viable deletion mutants of Bacillus subtilis bacteriophage SPO2.

Spontaneous deletion mutants of the bacteriophage SPO2, which are viable and retain their temperate character, were isolated using a heat-EDTA enrichment step. They were identified by endonuclease digestion and agarose-gel electrophoresis of phage DNA. Two of the nine mutants were characterized in detail. Both mutants have a 2.3 Md deletion removing the single BglII site and two of the XbaI fragments. The deletion extends 1.0 Md to one side of the former BglII site and 1.3 Md on the other side. This region of the SPO2 genome is non-essential for either lysogeny or viable phage production and thus is a suitable region for the insertion of exogenous DNA fragments.

Cloning and expression of a Streptomyces fradiae neomycin resistance gene in Escherichia coli.

A Streptomyces fradiae DNA sequence, which codes for a neomycin phosphotransferase, has been subcloned from the Streptomyces recombinant plasmid pIJ2 [a chimera between the Streptomyces plasmid SLP1.2 and chromosomal DNA containing a neomycin (Nm) resistance gene] into the BamHI restriction enzyme site of pHV14. Three different recombinant plasmids (pWHR1, pWHR2, pWHR3) have been isolated which transform Escherichia coli to Nm resistance. Southern transfer hybridization experiments show that the recombinant plasmids contain the cloned Streptomyces Nm resistance gene, and lysates of E. coli containing the recombinant plasmids were shown to have Nm phosphotransferase activity, demonstrating that a gene from Streptomyces can be expressed in E. coli.

New shuttle vectors for Bacillus subtilis and Escherichia coli which allow rapid detection of inserted fragments.

Two new shuttle vectors have been constructed by fusing the Escherichia coli plasmid pUC9 with the Staphylococcus aureus plasmids pU110 and pC194. The resulting hybrids replicate in both E. coli and Bacillus subtilis and contain seven restriction sites within a part of the lacZ gene. Insertion of foreign DNA into those sites can be easily detected in E. coli and hybrid plasmids can subsequently be transformed into B. subtilis.

Expression of thymidylate synthetase activity in Bacillus subtilis upon integration of a cloned gene from Escherichia coli.

The gene from Escherichia coli encoding thymidylate synthetase was cloned in the plasmid pBR322. The resulting chimeric plasmid, pER2, was effective in transforming both E. coli and Bacillus subtilis to thymine prototrophy. Uncloned linear E. coli chromosomal DNA was unable to transform thymine-requiring strains of B. subtilis to thymine independence. Linearization of the chimeric plasmid, pER2, with restriction enzymes markedly diminished its ability to transform B. subtilis auxotrophs. The Thy+ transformants derived from the transformation of B. subtilis with pER2 DNA did not contain detectable extrachromosomal DNA as demonstrated by Southern hybridization patterns and centrifugation in CsCl gradients of DNA isolated from B. subtilis colonies transformed with the chimeric plasmid. We conclude that the DNA from the chimeric plasmid was integrated into the chromosome of B. subtilis, demonstrating that extensive homology is not required for the integration of foreign DNA. This is the first reported case of a gene from a Gram-negative bacterium functioning in a Gram-positive organism.

Effect of site-specific endonuclease digestion on the thyP3 gene of bacteriophage phi 3T and the thyP11 gene of bacteriophage rho11.

phi 3T and rho11 are closely related bacteriophages of Bacillus subtilis which can "convent" thymine auxotrophs to thymine prototrophs upon infection or transfection. The effect of endonuclease digestion on the ability of both bacteriophage and prophage DNA from phi eT and rho11 to transform for thymine prototrophy was determined. All of the endonucleases tested: BamHI, Bg/II, BsuRI, EcoRI, HindII+ III, and HpaII reduced the efficiency of thyP transformation to an equal extent in prophage and bacteriophage DNA. Only HpaII completely abolished thyP transformation. The reduction in transformation with BamHI, Bg/II, BsuRI, EcoRI, and HpaII fragments is size related. The thyP transforming fragments generated by these endonucleases are potentially clonable.

Transformation of Bacillus subtilis and Escherichia coli by a hybrid plasmid pCD1.

The gene thyP3 from Bacillus subtilis bacteriophage phi 3T was cloned in the plasmid pMB9. The resulting chimeric plasmid, pCD1, is effective in transforming both Escherichia coli and Bacillus subtilis to thymine prototrophy. The activity of the thyP3 gene product, thymidylate synthetase, was assayed and found to be 9 times greater in a transformed strain of Escherichia coli than in a phi 3T lysogen of Bacillus subtilis. The physical location of restriction sites has been determined for two related plasmids pCD1 and pCD2. Hybridization studies clearly indicate that the plasmid gene responsible for Thy+ transformation is the gene from the bacteriophage phi 3T. The lack of restriction in this transformation process is consistent with our previous studies using bacterial DNA in heterospecific exchanges indicating that the nucleotide sequence surrounding the gene is the dominant factor in determining interspecific transformation.

Evidence for prokaryotic transcription and translation control regions in the human factor IX gene.

A human factor IX cDNA clone isolated from a liver cDNA library constructed in phage lambda gt11 vector was shown to express factor IX protein in Escherichia coli. A factor IX immunospecific protein of 46.8 kDa was expressed, but was not a beta-galactosidase-factor IX fusion protein. Expression was seen when the factor IX cDNA was cloned into two different vector systems, lambda gt11 and pUC9, in both orientations with respect to the vector lacZ promoter. The expression of factor IX was not under control of the lacZ promoter of either vector system. In addition, when the factor IX cDNA fragment was subcloned in both orientations into a promoterless cloning vector (p CPP3), the factor IX cDNA fragment demonstrated promoter activity when inserted in only one orientation resulting in expression of chloramphenicol acetyl transferase in E. coli and Bacillus subtilis. A DNA computer search of the N-terminal sequences of the factor IX gene revealed prokaryotic-like promoter and ribosome-binding site (RBS) sequences with strong homology to the E. coli consensus sequences. The predicted sites homologous with prokaryotic promoter and RBS consensus sequences are followed by an in-frame methionine which could correspond to the translation start codon of the expressed factor IX. This report provides the first evidence that a eukaryotic gene encodes the information necessary for both transcription and translation to control gene expression in a prokaryotic host.

Construction and characterization of a new shuttle vector, pLES2, capable of functioning in Escherichia coli and Neisseria gonorrhoeae.

In vitro recombination techniques were used to construct a bifunctional shuttle vector capable of functioning in Neisseria gonorrhoeae and Escherichia coli. This 6-kb plasmid contains a selectable phenotype, beta-lactamase production, which functions in both organisms. It also contains the lac region from pUC9 that allows for the direct selection of hybrid plasmids in the appropriate E. coli hosts by disruption of beta-galactosidase alpha complementation. The lac region contains several unique restriction sites useful for cloning: EcoRI, SmaI, BamHI and SalI.

Cloning and mapping of the dihydrofolate reductase gene of Bacillus subtilis.

The structural gene for dihydrofolate reductase (dfrA) from the Bacillus subtilis 168 chromosome has been cloned, along with the thyB gene, on a 4.5-kb insert contained on chimeric plasmid pER1. The presence of the dfrA gene on pER1 was demonstrated by showing that: (i) transformation of Escherichia coli strains RUE10(Thy-) and RUE11(Thy+) with pER1 resulted in a 60 to 130-fold increase in dihydrofolate reductase (DFRase) activity with a turnover number characteristic of that of B. subtilis and (ii) pER1-mediated transformation of trimethoprim-resistant E. coli strain D05, which overproduced a DFRase with a decreased affinity for trimethoprim, resulted in a 41-fold increase in DFRase activity with an affinity for trimethoprim similar to that of the B. subtilis enzyme. The dfrA gene was mapped to the 200 degrees region of the B. subtilis chromosome, and the gene order was established as thyB dfrA ilvA. Furthermore, the dfrA gene was shown to be linked closely (95-99% cotransformation) to the thyB gene.

The role of the FDA in the effort against AIDS.

The Food and Drug Administration has instituted several pro-active measures to expedite the review of treatments, diagnostics, and vaccines for AIDS and related conditions. In particular, the agency has established a special designation--1-AA--for a potential AIDS product which gives top priority to its review. This special expedited review process for AIDS products has provided for greater cooperation between their sponsors and FDA's reviewers. AIDS products also receive prompt consideration for orphan product status--a status providing financial incentives to the developers of treatments for certain rare and complex diseases. FDA's special procedures for AIDS drugs have resulted in several major advances in available AIDS treatments. Foremost among these was the FDA's review and approval of zidovudine (commonly known as AZT) as the first effective palliative for AIDS within 107 days--an agency record. Similarly, the agency quickly evaluated and approved ELISA and Western blot diagnostic kits for detecting the presence of HIV antibody. These test kits have made an important contribution to safeguarding the nation's blood supply. The agency has also instituted new "treatment" investigational new drug regulations to allow earlier pre-approval distribution of promising experimental treatments to patients with immediately life-threatening conditions, including persons with AIDS. Under this system and its earlier prototype, eligible AIDS patients were able to receive pre-approval treatment with zidovudine and trimetrexate (an experimental drug for the treatment of AIDS patients with Pneumocystis carinii pneumonia who have experienced severe adverse reactions using standard approved therapies). The agency has made institutional reforms to effectively streamline the review of candidate AIDS treatments and vaccines. Two new centers within the agency have been established for the processing of drug and biologics. In addition,reviewing divisions have been created within these centers to give specialized attention to drugs and biologics designed to treat AIDS or related conditions.These efforts and the other aforementioned reforms, in part, have lead to the initiation of more than 100 ongoing clinical studies of potential drugs for AIDS and related conditions, as well as the clinical testing of two candidate vaccines against HIV. In other areas, FDA has increased inspections of the manufacturing and processing of condoms and begun a surveillance and sampling program to insure the quality of latex surgical gloves. The agency has worked with other authorities to move against quack AIDS products and to educate the public concerning this health fraud.FDA hopes that through all these efforts it can help researchers in government, academia, and industry advance the development, testing, and review of safe and effective therapies, preventatives,and diagnostics for AIDS and related conditions.

An interview with FDA Commissioner Frank Young. Interview by Carmella Bocchino.

The Food and Drug Administration (FDA) has recently been the target of congressional investigations and has seen recent changes in its approval procedures. In this interview, FDA Commissioner Frank Young responds to harsh congressional criticisms and details the FDA approval process.