Respiratory syncytial virus immune globulin: decisions and costs.

A decision analysis was used to evaluate the economic effectiveness of respiratory syncytial virus immune globulin (RSVIG) prophylaxis on selected pediatric populations at risk for developing RSV bronchiolitis or all respiratory illness-related hospitalizations. We compared costs, outcomes, and cost-effectiveness of administering RSVIG to no treatment in different pediatric populations, including those at risk of developing RSV-bronchiolitis and those at risk of developing any respiratory illness-related hospitalization. We observed that if only infants at high risk of severe RSV infections received treatment with RSVIG, a calculated cost saving of about 27,000 dollars per hospitalization prevented were realized. If the Food and Drug Administration (FDA)-approved indications for RSVIG were followed, the cost to prevent one hospitalization due to RSV bronchiolitis would be over 53,000 dollars. If the aim, however, was to prevent all respiratory illness-related hospitalizations for this broader population, a much lower cost (4,000 dollars) to prevent one hospitalization would result. In this situation, cost neutrality was possible, with a therapy cost of 2,843 dollars compared to the actual average therapy cost of 4,444 dollars. Sensitivity analysis showed that the model was relatively insensitive to all variables, with the exceptions of costs related to RSVIG and intensive care unit (ICU) admissions. We conclude that RSVIG resulted in cost savings if therapy were reserved for the infants who are at highest risk for developing severe RSV infections. RSVIG is not cost-effective for preventing RSV bronchiolitis when used according to the FDA-approved indications. Education that emphasizes frequent hand-washing, avoidance of passive smoking, and lessening exposure to sick children remains the least expensive prevention tool.

Adverse events and cost savings three years after implementation of guidelines for outpatient contrast-agent use.

The ability of guidelines limiting the use of low-osmolality contrast media (LOCM) to save money without jeopardizing patient care was studies. In February 1993 an academic medical center implemented guidelines to reduce the use of LOCM for outpatient computed tomography and excretory urography; the guidelines limited LOCM to patients at high risk of adverse reactions to contrast agents. Data on contrast media received and frequency of adverse events were compiled from billing sheets and incident reports for March 1993 through February 1996. The number of patients receiving LOCM over the three years was 1325, and the number receiving high-osmolality contrast media (HOCM) was 4435. Of the HOCM recipients, 165 (3.7%) had adverse reactions; 0.4% of these reactions were major, 3.1% were minor, and 0.2% were extravasations. Among LOCM-treated patients, 35 (2.7%) had adverse reactions; 0.5% were major, 1.7% were minor, and 0.5% were extravasations. The only significant difference in adverse effects between the groups was in the frequency of minor reactions. The costs of HOCM and LOCM over the three years were $54,660 and $152,523, respectively. Had 90% of the 5760 patients received LOCM, the total cost of contrast agents would have been $603,723; thus, the estimated drug cost saving was $396,540, or $132,180 annually. With costs of treating adverse events factored in, the net annual cost saving was $132,093. Guidelines limiting the use of LOCM to high-risk patients saved an academic medical center an estimated $132,093 annually in drug costs for specific outpatient imaging procedures, without adversely affecting patient care.

The use of dietary supplements in pediatrics: a study of echinacea.

Alternative medical therapies are commonly used and have increased in popularity. Although patients may not always disclose the use of alternative therapies, they may seek advice regarding their use, especially for children. Regulation and standardization of these modalities, especially botanicals, is incomplete. The University of Arizona has initiated a study of the use of echinacea in the prevention of recurrent otitis media. A review of echinacea preparations was undertaken, and this report discusses the complexities surrounding the use of this dietary supplement. The number and diversity of echinacea preparations are detailed; the role of the physician as "botanical" advisor to patients and families is examined.

Investigational drug tracking: Phases I-III and NDA submissions--Part I.

The author catalogs over 800 investigational drugs/biologicals currently in Phase I, II or III clinical trials or drugs/biologicals submitted to the FDA as new drug applications. The list assists in predicting when new drugs will be marketed. The entries include generic/chemical name, investigational drug number, synonyms, trade names, manufacturers, clinical trial status, predicted approval year, indications or drug class, whether the drug has been developed through biotechnology, and references. Entries were gleaned from medical journals, stock market analysis publications, and the Pharmaceutical Manufacturers Association's Medicines in Development Series. The list is alphabetized by the generic/chemical name or investigational drug number and cross-indexed by the trade name and synonyms. The list reflects those drugs which were not FDA approved as of April 15, 1994. Part I includes the trade name and synonym cross-indexes and the beginning of the main alphabetical listing by generic/chemical name or investigational drug number.

Investigational drug tracking: phases I-III and NDA submissions--Part II.

The author catalogs over 800 investigational drugs/biologicals currently in Phase I, II or III clinical trials or drugs/biologicals submitted to the FDA as new drug applications. Part I of this article appeared in the September issue of Hospital Pharmacy. The list assists in predicting when new drugs will be marketed. The entries include generic/chemical name, investigational drug number, synonyms, trade names, manufacturers, clinical trial status, predicted approval year, indications or drug class, whether the drug has been developed through biotechnology, and references. Entries were gleaned from medical journals, stock market analysis publications, and the Pharmaceutical Manufacturers Association's Medicines in Development Series. The list is alphabetized by the generic/chemical name or investigational drug number and cross-indexed by the trade name and synonyms. The list reflects those drugs which were not FDA approved as of April 15, 1994. Part I concludes with the remaining alphabetical listing by generic/chemical name or investigational drug number.

A thioredoxin gene fusion expression system that circumvents inclusion body formation in the E. coli cytoplasm.

We have developed a versatile Escherichia coli expression system based on the use of E. coli thioredoxin (trxA) as a gene fusion partner. The broad utility of the system is illustrated by the production of a variety of mammalian cytokines and growth factors as thioredoxin fusion proteins. Although many of these cytokines previously have been produced in E. coli as insoluble aggregates or "inclusion bodies", we show here that as thioredoxin fusions they can be made in soluble forms that are biologically active. In general we find that linkage to thioredoxin dramatically increases the solubility of heterologous proteins synthesized in the E. coli cytoplasm, and that thioredoxin fusion proteins usually accumulate to high levels. Two additional properties of E. coli thioredoxin, its ability to be specifically released from the E. coli cytoplasm by osmotic shock or freeze/thaw treatments and its intrinsic thermal stability, are retained by some fusions and provide convenient purification steps. We also find that the active-site loop of E. coli thioredoxin can be used as a general site for small peptide insertions, allowing for the high level production of soluble peptides in the E. coli cytoplasm.

Production of recombinant bovine enterokinase catalytic subunit in Escherichia coli using the novel secretory fusion partner DsbA.

Enterokinase (EK) is a heterodimeric serine protease which plays a key role in initiating the proteolytic digestion cascade in the mammalian duodenum. The enzyme acts by converting trypsinogen to trypsin via a highly specific cleavage following the pentapeptide recognition sequence (Asp)4-Lys. This stringent site specificity gives EK great potential as a fusion protein cleavage reagent. Recently, a cDNA encoding the catalytic (light) chain of bovine enterokinase (EKL) was identified, characterized, and transiently expressed in mammalian COS cells. We report here the production of EKL in Escherichia coli by a novel secretory expression system that utilizes E. coli DsbA protein as an N-terminal fusion partner. The EKL cDNA was fused in-frame to the 3'-end of the coding sequence for DsbA, with the two domains of the fusion protein separated by a linker sequence encoding an enterokinase recognition site. Active, processed recombinant EKL (rEKL) was generated from this fusion protein via an autocatalytic cleavage reaction. The enzymatic properties of the bacterially produced rEKL were indistinguishable from the previously described COS-derived enzyme. Both forms of rEKL were capable of cleaving peptides, polypeptides and trypsinogen with the same specificity exhibited by the native heterodimeric enzyme purified from bovine duodena. Interestingly, rEKL activated trypsinogen poorly relative to the native heterodimeric enzyme, but was superior in its ability to cleave artificial fusion proteins containing the (Asp)4-Lys recognition sequence.

Evidence that both protium and deuterium undergo significant tunneling in the reaction catalyzed by bovine serum amine oxidase.

The magnitudes of primary and secondary H/T and D/T kinetic isotope effects have been measured in the bovine serum amine oxidase catalyzed oxidation of benzylamine from 0 to 45 degrees C. Secondary H/T and D/T kinetic effects are small and in the range anticipated from equilibrium isotope effects; Arrhenius preexponential factors (AH/AT and AD/AT) determined from the temperature dependence of isotope effects also indicate semiclassical behavior. By contrast, primary H/T and D/T isotope effects, 35.2 +/- 0.8 and 3.07 +/- 0.07, respectively, at 25 degrees C, are larger than semiclassical values and give anomalously low preexponential factor ratios, AH/AT = 0.12 +/- 0.04 and AD/AT = 0.51 +/- 0.10. Stopped-flow studies indicate similar isotope effects on cofactor reduction as seen in the steady state, consistent with a single rate-limiting C-H bond cleavage step for Vmax/Km. The comparison of primary and secondary isotope effects allows us to rule out appreciable coupling between the primary and secondary hydrogens at C-1 of the substrate. From the properties of primary isotope effects, we conclude that both protium and deuterium undergo significant tunneling in the course of substrate oxidation. These findings represent the first example of quantum mechanical effects in an enzyme-catalyzed proton abstraction reaction.

Effect of HIPping, stress and surface finish on the environmental degradation of Y-TZP ceramics.

Hot isostatically pressed (HIPped) and hot pressed (designated unHIPped) bar samples of yttria stabilized tetragonal zirconia polycrystalline ceramic (3Y-TZP) were subjected to three point bend testing in water at 90 degrees C. HIPped femoral heads with three different surface finishes were also aged in 90 degrees C water. The early stages of the environment induced tetragonal to monoclinic transformation was monitored as a function of time by X-ray diffraction, white light interferometry and scanning electron microscopy. HIPped samples were found to transform less readily than unHIPped samples and have a longer incubation period prior to transformation. There was an increase in the amount of monoclinic phase detected following the application of stress, particularly on the compression surface. Microcraters, believed to result from the expulsion of transformed grains when stress was applied, were observed on tension surfaces, particularly of unHIPped samples. There was no effect of surface roughness on the environment induced transformation for the range of surface finishes investigated.

Prediction of the secondary structures of bovine blood coagulation factor IX, factor X, and prothrombin.

The secondary structures of bovine blood coagulation factors IX and X, as well as that of bovine prothrombin, were predicted on the basis of a computerized combination of the Chou-Fasman and Burgess algorithms. Refinements in the predictions were made after consideration of the content of various secondary structures, as determined by circular dichroism studies of these same proteins. The final turn assignments were in good agreement with those assigned with use of an algorithm involving pattern matching of beta-turns in proteins of known structure.

Role of internal thermodynamics in determining hydrogen tunneling in enzyme-catalyzed hydrogen transfer reactions.

Previous investigations have indicated a role for hydrogen tunneling in the yeast alcohol dehydrogenase catalyzed oxidation of benzyl alcohol [Cha, Y., Murray, C. J., & Klinman, J. P. (1989) Science 243, 1325] and the bovine plasma amine oxidase catalyzed oxidation of benzylamine [Grant, K.L., & Klinman, J. P. (1989) Biochemistry 28,6597]. In the present studies, values of protium to tritium and deuterium to tritium isotope effects and their temperature dependencies have been measured using ring-substituted substrates for yeast alcohol dehydrogenase and bovine plasma amine oxidase, revealing tunneling in each case. The results of these studies indicate that hydrogen tunneling is a general phenomenon and is not limited to enzyme reactions with degenerate energy levels for bound substrates and products. An analysis of internal thermodynamics in the yeast alcohol dehydrogenase reaction shows that tunneling occurs when delta H degrees is endothermic and that the degree of tunneling appears to increase as delta H degrees decreases toward zero.

Pharmacy-coordinated investigational drug services.

The concept of a pharmacy-coordinated investigational drug service (IDS) is proposed as an approach to better control of investigational drugs. The IDS should be considered as set of service functions aimed to ensure that investigational drug studies in the hospital are executed in a safe, effective, and efficient manner. These functions are the distribution and control of study drugs, clinical services, research activities, and management of clinical studies. The IDS will vary from hospital to hospital, and should reflect the extent to which the institution is involved with research, available resources, and the needs of the hospital. Successful development and operation of an IDS depend on proper planning and continued effective management. The IDS will require resources of personnel, money, and facilities, space, and equipment. The primary expense of the IDS (probably about 80%) will be personnel. Job descriptions for each staff position should be prepared, and a complete set of standard operating policies and procedures is required. Periodic reports summarizing the activities of the IDS and an ongoing quality assurance program are needed. To create an IDS, the pharmacy must acquire the necessary approvals, authority, and resources. The IDS will benefit patients, nursing staff, clinical investigators, hospital risk management, and sponsors of clinical research. These benefits can be used to gain support for the IDS concept. Once the IDS is established, the best promotion will be a successful track of accomplishing the IDS objectives.

Cloning and functional expression of a cDNA encoding the catalytic subunit of bovine enterokinase.

Enterokinase (enteropeptidase) is a heterodimeric serine protease that is responsible for the physiological activation of trypsinogen by highly specific cleavage of the trypsinogen activation peptide following the sequence (Asp)4-Lys. In this paper, we report the cloning and functional expression of a cDNA encoding the catalytic domain (light chain) of bovine enterokinase. The nucleotide sequence of this cloned cDNA predicts a 235-amino acid polypeptide that shares a high degree of homology with a variety of mammalian serine proteases involved in digestion, coagulation, and fibrinolysis. We have developed a novel expression method for the enzyme which utilizes the secretory leader and propeptide of the mammalian serine protease PACE fused to the enterokinase light chain amino terminus. Efficient cleavage of the paired dibasic amino acid cleaving enzyme (PACE) propeptide was achieved by coexpression with human PACE or yeast KEX2. The mature product migrates at 43,000 Da on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, comparable to light chain derived from bovine duodena, and exhibited high levels of activity in cleaving the enterokinase-specific fluorogenic substrate Gly-(Asp)4-Lys-beta-naphthylamide. The recombinant single-chain form of enterokinase was also capable of activating trypsinogen, indicating that the specificity of the enzyme for its natural substrate is retained even in the absence of the noncatalytic enterokinase heavy chain.

The future of medication information practice: a consensus.

OBJECTIVE: To analyze the current practice of drug information and develop a strategic plan for a "valued" specialty of medication information practice. DATA SOURCES: The Consortium for the Advancement of Medication Information, Policy, and Research (CAMIPR) met in June 1994 to initiate a strategic plan for a future of medication information practice. A multidimensional situation analysis and strategic planning process was conducted and the results are discussed. RECOMMENDATIONS: Trends in health care (e.g., healthcare reform, managed care) will impact the future of medication information practice, and the medication information specialist must evolve with society's values. Medication information practice must transform and attention will likely focus on medication policy research/ development and information systems. However, new skills, resources, and relationships must be developed to facilitate this evolution. In addition, interest in the practice of drug information has declined. Strategies are presented to enhance the "value" and "image" of future medication information practice.

Histidine patch thioredoxins. Mutant forms of thioredoxin with metal chelating affinity that provide for convenient purifications of thioredoxin fusion proteins.

A cluster of surface amino acid residues on Escherichia coli thioredoxin were systematically mutated in order to provide the molecule with an ability to chelate metal ions. The combined effect of two histidine mutants, E30H and Q62H, gave thioredoxin the capacity to bind to nickel ions immobilized on iminodiacetic acid- and nitrilotriacetic acid-Sepharose resins. Even though these two histidines were more than 30 residues apart in thioredoxin's primary sequence, they were found to satisfy the geometric constraints for metal ion coordination as a result of the thioredoxin tertiary fold. A third histidine mutation, S1H, provided additional metal ion chelation affinity, but the native histidine at position 6 of thioredoxin was found not to participate in binding. All of the histidine mutants exhibited decreased thermal stability as compared with wild-type thioredoxin; however, the introduction of an additional mutation, D26A, increased their melting temperatures beyond that of wild-type thioredoxin. The metal chelating abilities of these histidine mutants of thioredoxin were successfully utilized for convenient purifications of human interleukin-8 and -11 expressed in E. coli as soluble thioredoxin fusion proteins.