In vitro Inhibitory Effects of Combinations of anti-Influenza Agents

To assess the possible interactions among candidate anti-influenza agents, dual combinations of rimantadine, ribavirin, 2′-deoxy-2′-fluoroguanosine (2-FDG) and 4-guanidino-Neu5Ac2en (GG167) were tested against clinical isolates of influenza A H3N2 and H1N1 subtype viruses in MDCK cells by ELISA. Each of the dual combinations showed additive effects, except for the combination of 2-FDG and ribavirin which was synergistic against the influenza A (H1N1) virus. However, this combination also showed enhanced cytotoxicity. In this assay system, influenza agents with differing mechanisms of antiviral interaction interacted in an additive fashion with respect to inhibition of viral replication.

The value of uncertainty in critical illness? An ethnographic study of patterns and conflicts in care and decision-making trajectories

BACKGROUND

With increasingly intensive treatments and population ageing, more people face complex treatment and care decisions. We explored patterns of the decision-making processes during critical care, and sources of conflict and resolution.

METHODS

Ethnographic study in two Intensive Care Units (ICUs) in an inner city hospital comprising: non-participant observation of general care and decisions, followed by case studies where treatment limitation decisions, comfort care and/or end of life discussions were occurring. These involved: semi-structured interviews with consenting families, where possible, patients; direct observations of care; and review of medical records.

RESULTS

Initial non-participant observation included daytime, evenings, nights and weekends. The cases were 16 patients with varied diagnoses, aged 19-87 years; 19 family members were interviewed, aged 30-73 years. Cases were observed for <1 to 156 days (median 22), depending on length of ICU admission. Decisions were made serially over the whole trajectory, usually several days or weeks. We identified four trajectories with distinct patterns: curative care from admission; oscillating curative and comfort care; shift to comfort care; comfort care from admission. Some families considered decision-making a negative concept and preferred uncertainty. Conflict occurred most commonly in the trajectories with oscillating curative and comfort care. Conflict also occurred inside clinical teams. Families were most often involved in decision-making regarding care outcomes and seemed to find it easier when patients switched definitively from curative to comfort care. We found eight categories of decision-making; three related to the care outcomes (aim, place, response to needs) and five to the care processes (resuscitation, decision support, medications/fluids, monitoring/interventions, other specialty involvement).

CONCLUSIONS

Decision-making in critical illness involves a web of discussions regarding the potential outcomes and processes of care, across the whole disease trajectory. When measures oscillate between curative and comfort there is greatest conflict. This suggests a need to support early communication, especially around values and preferred care outcomes, from which other decisions follow, including DNAR. Offering further support, possibly with expert palliative care, communication, and discussion of 'trial of treatment' may be beneficial at this time, rather than waiting until the 'end of life'.

Interaction of infectious viral particles with a quaternary ammonium chlorid (QAC) surface

The antiviral activity of a surface-bonded quaternary ammonium chloride (QAC) was examined in this study. The mechanism of inactivation was elucidated by a combination of infectivity assay, radioactive labeling assay, and sedimentation analysis. Although the virions are still infectious when attached onto the chemically modified surface, we found these viruses are inactivated if they are eluted from the surface. The inactivation is caused by the disruption of the viral envelope with subsequent release of the nucleocapsid. No evidence indicates the released nucleocapsid is further disrupted. An enveloped virus shows a much higher affinity for the QAC-treated surface than a nonenveloped one due to hydrophobic interaction. The QAC-treated beads can effectively remove the enveloped viruses at low protein concentrations. The titer of herpes simplex virus was reduced by a factor of nearly 5 logarithm units in a 0.5 wt % bovine serum albumin solution with less that 10% protein loss. However, the presence of proteins in the solution reduced both the rate and capacity of this nonspecific adsorption-inactivation process. As a consequence, the removal efficiency is relatively poor in solutions with high protein content.

The views of patients with advanced cancer regarding participation in serial questionnaire studies

Longitudinal research helps to clarify changing needs and the timing of treatments and referral but is hampered by poor recruitment and retention of participants. We explored, using semi-structured interviews in a cross-sectional design, the views and preferences of patients with advanced cancer on taking part in planned longitudinal questionnaire-based research studies. Patients with advanced lung and colorectal cancer were recruited from outpatient clinics in a London hospital. Semi-structured interviews were undertaken to explore their views about taking part in a specific future questionnaire study and their preferences regarding format. In all, 20 of 47 patients initially identified were recruited. Their preferences for the planned questionnaire study were for face-to-face interviews undertaken at home from late morning onwards with recontact at a mean of 6 weeks. Fluctuating symptom control needs could result in unexpected admission to or discharge from hospital. Developing flexible and responsive recruitment procedures is vital to retain patient participation as more than one contact might be required to successfully conclude an interview.

Recombinant osteoprotegerin decreases tumor burden and increases survival in a murine model of multiple myeloma

The aim of the present study was to determine whether modifying the local bone environment with osteoprotegerin (OPG), the soluble decoy receptor for receptor activator of nuclear factor-kappaB (RANK) ligand, could affect tumor burden and survival in the 5T33MM murine model of multiple myeloma. Treatment of mice, injected with 5T33MM cells, with recombinant OPG (Fc-OPG) caused a significant decrease in serum paraprotein and tumor burden and a significant increase in time to morbidity. This was associated with a decrease in osteoclast number in vivo but had no effect on apoptosis and proliferation of 5T33MM cells in vitro. These data indicate that targeting the bone microenvironment by inhibiting the interaction between RANK ligand and RANK with Fc-OPG not only inhibits the development of myeloma bone disease but also decreases tumor growth and increases survival.

Clinical disorders of bone resorption

Clinical disorders in which bone resorption is increased are very common and include Paget's disease of bone, osteoporosis, and the bone changes secondary to cancer, such as occur in myeloma and metastases from breast cancer. Clinical disorders of reduced bone resorption are less common and often have a genetic basis, e.g. in osteopetrosis, and in pycnodysostosis due to cathepsin K deficiency. Bone is metabolically active throughout life. After skeletal growth is complete, remodelling of both cortical and trabecular bone continues and results in an annual turnover of about 10% of the adult skeleton. The commonest disorder of bone resorption is osteoporosis, which affects one in three women over 50 years. Its pathophysiological basis includes genetic predisposition and subtle alterations in systemic and local hormones, coupled with environmental influences. Treatment depends mainly on drugs that inhibit bone resorption, either directly or indirectly. This includes bisphosphonates, oestrogens, synthetic oestrogen-related compounds (SERMs--selective oestrogen receptor modulators) and calcitonin. The most widely used drugs for all disorders of increased bone resorption, including osteoporosis, are the bisphosphonates. Recent elucidation of their mode of action, together with the rapidly increasing knowledge of regulatory mechanisms in bone biology, offers many opportunities for the development of new therapeutic agents.

Cancer services. Left to chance

Most primary care groups/trusts have cancer lead posts and have some involvement in planning and commissioning cancer services. Cancer is not a high priority in comparison to other national service frameworks and the transition to PCT status. PCG/Ts want help and information about developing cancer services but not all want this now. Most PCG/Ts have some involvement in cancer networks but information needs exist about their role and potential.

Educational opportunities in palliative care: what do general practitioners want?

It is important to support general practitioners (GPs) in maintaining and developing their palliative care skills as most of the final year of a patient's life is spent at home under the care of the primary health care team. The training needs and uptake of GPs have been explored, but little is known about how GP educational preferences vary. The aim of this study was to explore the current educational preferences of GPs in different geographical locations as part of an evaluation of an educational intervention. The methods used included postal questionnaires sent to 1061 GPs. Results from 640 (60%) of GPs revealed that half (51%) wanted education in symptom control for non-cancer patients. More inner-city GPs wanted education in opiate prescribing (43%), controlling nausea and vomiting (45%), and using a syringe driver (38%) than their urban and rural colleagues (26%, 29% and 21%, respectively). Increased educational preference and increased difficulty in accessing information was associated with reduced confidence in symptom control. To maximize educational uptake it will be important for educational strategies to be developed and targeted according to variations in demand, and in particular to respond to the need for palliative care education in symptom control for patients suffering from advanced non-malignant disease.

Patient-perceived benefits of and barriers to using out-of-hours primary care centres

BACKGROUND

The rapid growth of GP co-operatives has encouraged the development of primary care centres, but little is known about patients' views and experiences of these new forms of out-of-hours service delivery.

OBJECTIVES

This study was designed to understand patients' views, expectations and experiences of attending an out-of-hours primary care centre which was part of an inner London GP co-operative.

METHODS

Systematic samples of patients using the out-of-hours service received semi-structured interviews covering the decision to contact the service, expectations and experience of the service and, if relevant, the experience of travelling to the primary care centre. Interviews were conducted by telephone between 7 and 10 days after patient contact.

RESULTS

Interviews were completed with 55.4% (72/130) of sampled patients who were primary care centre attenders, 50.0% (47/94) of those receiving telephone advice and 45.3% (53/117) of those receiving a home visit. Most attenders of the primary care centre said that they were satisfied with the consultation (90.0%, 65) and were able to get all the help they needed (83%, 60). The speed of being seen and the opportunity of having a face-to-face consultation were key benefits identified. For some, this outweighed difficulties experienced in attending the centre, including arranging transport, caring for other children, managing several children on the journey and travelling while ill. The main barriers patients identified for not wanting to attend the primary care centre included feeling too ill to travel, having other dependants to care for or lacking transportation.

CONCLUSIONS

While primary care centres offer patients speedy access to face-to-face consultations, there are a range of obstacles which are encountered. Those who are socially disadvantaged appear likely to experience greatest difficulty, raising concerns about equity in access to services. Out-of-hours services may need to give consideration to patient transport and a more flexible approach to visiting at home if such inequities are to be avoided.

Patients' experiences of receiving telephone advice from a GP co-operative

BACKGROUND

The use of the telephone to deliver health care advice has increased considerably in recent years. Little research has been carried out to explore the experience of patients who receive such advice and its acceptability.

OBJECTIVES

The aim of this study is to describe the expectations of patients, or third party callers, who had contacted a GP out-of-hours co-operative and their satisfaction with telephone advice received.

METHODS

Semi-structured interviews were conducted by telephone 7-10 days after contact with one inner city GP co-operative.

RESULTS

A total of 47 telephone consultations were followed up with an interview. Of these, 23 (48.9%) callers had expected to be offered a home visit when they called. Reasons for wanting a home visit were either to do with the nature of the condition and its perceived severity, problems in being able to attend the primary care centre and the risks of travel, or because of problems in communicating over the telephone. Satisfaction with telephone consultations centred mostly on the doctor being able to provide reassurance and give adequate time to allay concerns. The most common reasons given for dissatisfaction were the caller feeling that the doctor could not make a correct diagnosis without having seen the patient, or the caller being made to feel that they were wasting the doctor's time. Many patients were anxious about their ability to describe symptoms over the telephone, or understand and follow the advice that they received.

CONCLUSIONS

There appears to be a need for patients to be better informed about the service they can expect to receive from GP co-operatives. Recent developments such as NHS Direct may have an influence on the telephone consultation rate to GP co-operatives.

Patient satisfaction with out-of-hours services; how do GP co-operatives compare with deputizing and practice-based arrangements?

BACKGROUND

Although the rapid growth in general practitioner (GP) co-operatives has met with GP satisfaction, little is known about patient satisfaction. This study compares patient satisfaction with co-operative, GP practice-based and deputizing arrangements within one geographical area 15 months after a co-operative had become established; and with telephone, primary care centre and home consultations within the co-operative.

METHODS

A validated postal questionnaire survey of weighted samples of patients making contact with the co-operative, practice-based and deputizing arrangements was undertaken.

RESULTS

A total of 1,823 (53.2 per cent) patients responded. There were no significant differences between organizations in terms of overall satisfaction, but patients using practice-based arrangements were significantly more satisfied with the waiting time for telephone consultations (p<0.001) and more satisfied with waiting times for home visits than deputizing patients (p=0.020). Within the co-operative, overall satisfaction, satisfaction with the doctor's manner and with the process of making contact was greater among those attending the primary care centre, and satisfaction with explanation and advice received greater than for patients receiving telephone consultations alone (p<0.01). Those receiving telephone advice reported increased information needs and help seeking during the following week (p< 0.05).

CONCLUSIONS

Overall, patients were as satisfied with the co-operative as with practice-based or deputizing service arrangements, although many concerns were expressed about the quality of service provision. Differences in satisfaction were greater between forms of service delivery within the co-operative. Dissatisfaction with telephone consultations needs to be considered, together with issues relating to equity in access to out-of-hours' primary care centre consultations and the potential impact of NHS Direct.

Providing palliative care in primary care: how satisfied are GPs and district nurses with current out-of-hours arrangements?

The complex needs of palliative care patients require an informed, expert, and swift response from out-of-hours general medical services, particularly if hospital admission is to be avoided. Few general practitioners (GPs) reported routinely handing over information on their palliative care patients, particularly to GP co-operatives. District nurses and inner-city GPs were least satisfied with aspects of out-of-hours care. Most responders wanted 24-hour availability of specialist palliative care. This indicates a need to develop and evaluate out-of-hours palliative care procedures and protocols, particularly for GP co-operatives, and to improve inter-agency collaboration.

The pharmacology of bisphosphonates and new insights into their mechanisms of action

Bisphosphonates are chemically stable analogs of inorganic pyrophosphate, which are resistant to breakdown by enzymatic hydrolysis. The biological effects of bisphosphonates on calcium metabolism were originally ascribed to their physico-chemical effects on hydroxyapatite crystals. Although such effects may contribute to their overall action, their effects on cells are probably of greater importance, particularly for the more potent compounds. Remarkable progress has been made in increasing the potency of bisphosphonates as inhibitors of bone resorption, and the most potent compounds in current use are characterized by the presence of a nitrogen atom at critical positions in the side chain which, together with the bisphosphonate moiety itself, seems to be essential for maximal activity. As a class the bisphosphonates offer a very effective means of treating Paget's disease.

Access to and use of out-of-hours services by members of Vietnamese community groups in South London: a focus group study

BACKGROUND

Communication difficulties, lack of knowledge of services and the appropriateness of services influence access to health care services by black and ethnic minority groups. These problems may be accentuated outside normal working hours. This may be so particularly for those who do not speak English as a first language, as interpreting services across the UK are extremely limited in the out-of-hours period.

OBJECTIVE

We aimed to describe the experiences and perceptions of members of the Vietnamese community groups in seeking out-of-hours health services and to identify potential solutions from participants' perspectives.

METHOD

This qualitative study used a focus group methodology. Participants were members of three established community groups in the South London boroughs of Southwark and Lewisham. Participants attended six focus groups which were conducted in Cantonese and Vietnamese.

RESULTS

Participants did not know about GPs' out-of-hours arrangements. And their access to the range of services normally available was limited. They were unable to communicate with health care professionals or answering services and were unaware of out-of-hours interpreting arrangements. Generally, participants were dependent on other people in gaining access to services. Some participants had used 999 services despite communication problems. Participants' experienced delays in seeking health care services and confusion regarding the medicines and advice given.

CONCLUSIONS

Communication difficulties limited knowledge of and access to out-of-hours services for the Vietnamese participants. Direct contact with interpreters in the out-of-hours period was suggested as a means of increasing participants' ability to gain access to services. Health service planners need to be aware of the difficulties experienced by such groups if issues of equity in gaining access to health care services are to be addressed.

Responding to out-of-hours demand: the extent and nature of urgent need

BACKGROUND

Little research has been undertaken concerning GPs' perceptions about urgent or 'appropriate' out-of-hours demand.

OBJECTIVE

We aimed to measure GPs' perceptions about patients' need for urgent out-of-hours general medical help according to indicators of physical, psychological/emotional and social need, and the medical necessity of a home visit.

METHODS

Twenty-five practices participated in an audit and research study whereby GPs completed an audit form for all contacts during November/December 1995 and February/March 1996. Each contact was assessed according to the indicators of urgent need and GPs commented on reasons for making such assessments.

RESULTS

Audit forms were completed on 1862 patients, and GPs considered that 66.6% (1027) of contacts had either a physically, psychologically/emotionally or socially urgent need for help and were uncertain about a further 10.7% (165). Over half (53.0%) were considered to have an urgent physical need, almost one-third (31.0%) to have an urgent psychological/emotional need and 10.1% (119) to have an urgent social need for help. Over half (55.2%) of visits were considered to be medically necessary, the majority of which (89.9%) were assessed as having an urgent physical need for help.

CONCLUSIONS

The findings raise questions about the strategic direction of newer forms of service delivery (GP Co-operatives) and suggest the need for further research to inform the strategic reduction in home visiting, particularly in inner-city areas where many residents have little access to transport out-of-hours to enable them to attend a primary care centre. GP co-operatives are, however, well placed to improve interagency working and cross-referral to other health and social service personnel, and respond more 'appropriately' to some psychological/emotional and social problems.

Phosphorylation of triciribine is necessary for activity against HIV type 1

Triciribine (TCN) is a tricyclic nucleoside with known antineoplastic and antiviral activity. It is a potent and selective inhibitor of HIV-1 and HIV-2, including strains known to be resistant to AZT or TIBO. TCN is phosphorylated to its 5'-monophosphate (TCN-P) by intracellular adenosine kinase (AK), but is not converted to di- or triphosphates. We now report that 5'-phosphorylation is requisite for the activity of TCN against HIV-1. CEM cells incubated with TCN at concentrations ranging from 0.1 to 330 microM gave intracellular TCN-P concentrations from 27 to 775 microM, respectively. There was no difference in the amount of intracellular TCN-P detected in uninfected compared with HIV-1-infected CEM cells. The antiviral effect of TCN against HIV-1 was strongly antagonized by the AK inhibitor 5-iodotubercidin (ITu). In contrast, TCN and ITu only exhibited additive cytotoxicity. The 5'-deoxy analog of TCN, which cannot be phosphorylated, had no antiviral effect against HIV-1 at a concentration more than 100 times higher than the IC50 of TCN. Similarly, TCN was not active against HIV-1 in an AK-deficient cell line (AA-2) at concentrations shown to inhibit the virus by >95% in CEM cells. Consistent with its AK-deficient phenotype, this cell line phosphorylated TCN to only 3% of the extent observed in CEM cells. We conclude that TCN must be phosphorylated to TCN-P for activity against HIV-1.

Working out of hours: the experiences and training needs of general practitioner registrars

Out-of-hours work has been identified as a major concern for registrars, and as contributing to the steady decline both in the number of applicants to vocational training schemes and in those practising as principals on completion of their training. Until now, little has been known about registrars' views about their experience of working out of hours and how this might be improved. The present study describes general practitioner (GP) registrars' current patterns of out-of-hours working and their perceptions about training needs.

Using out-of-hours services: general practice or A&E?

BACKGROUND

General medical and accident and emergency (A&E) services are the two major providers of open access out-of-hours care, and there are widespread concerns about rising and non-urgent demand presented to both.

METHODS

This paper examines the differential use of these services out of hours, in an audit and research study two A&E departments and 21 practices in South London. It focuses on aspects of demand, including time of contact, age-related usage and nature of presenting complaints. Through interviews with a subsample of 82 patients who attended A&E, it also provides a more qualitative focus on differential decision making.

RESULTS

Findings show that there are differences in the way A&E and general medical services are used in terms of age-related demand and aspects of presenting complaints. Significantly more families with children aged under 10 contacted a GP, and whilst more digestive, respiratory and viral/non-specific complaints were presented to GPs, musculoskeletal problems constituted the largest category of complaints presented at the A&E departments. However, some usage relating to perceived and actual availability of services appeared to be interchangeable in terms of site-of-help seeking.

CONCLUSION

There is a need for a collaborative multi-method approach to respond to and influence demand.

Changes in patient screening for a clinical study of dental implants after increased awareness of tobacco use as a risk factor

Independent external monitoring committees are an important part of scientific clinical trials. They monitor patient safety, study progress, investigators' performance, and accurate interpretation/reporting of the study data. Data trends observed by a study monitoring committee detected a change in the pattern of patient screening by investigators after an increased awareness that tobacco use could directly compromise the osseointegration of root-form dental implants. This increased awareness is believed to have altered the number of active smokers accepted into a multicenter prospective dental implant study. Recent data analyses indicate that the success ratios were improved by alterations in this discretionary inclusion-exclusion criterion.

Creating a shared vision of out of hours care: using rapid appraisal methods to create an interagency, community oriented, approach to service development

OBJECTIVES

To undertake a district wide review of out of hours primary health care services and identify the views of users and providers about current arrangements and options for development.

DESIGN

A range of qualitative and quantitative survey methods based on rapid appraisal methods, modified to apply to an inner city district.

SETTING

Socially deprived, multiethnic district in south east London with a population of over 700,000.

MAIN OUTCOME MEASURES

Strengths and weaknesses of current out of hours services and suggestions for developments.

RESULTS

Widespread dissatisfaction with current arrangements was identified, with specific problems relating to access, availability, demand for services, and interagency communication. Several areas for development were identified, including the establishment of an out of hours cooperative, multiagency primary care emergency centres, and telephone advice-triage. Many of these are now being planned or piloted.

CONCLUSIONS

Rapid appraisal provided a helpful method, enabling partnerships to be established between local agencies and users in relation to service development. The shared understanding and commitment to improving services that resulted is now having a major impact on out of hours care in the district.

Ribonucleotide reductase: an important enzyme in the replication of herpes simplex virus type 1 and a target for antiviral chemotherapy

Herpes simplex virus encodes a ribonucleotide reductase that catalyzes the formation of deoxyribonucleotides from ribonucleotides. The enzyme is not essential for either viral DNA synthesis or replication, yet inhibitors of this enzyme suppress viral replication. To clarify the role of the ribonucleotide reductase in virus infection and to evaluate it as an antiviral target, the metabolism of deoxyribonucleotides in infected cells was examined. Our results show that the cellular ribonucleotide reductase is incapable of generating adequate deoxyribonucleoside triphosphate pools to support efficient virus replication. Additionally, we have shown that the virus is unable to efficiently utilize salvaged deoxyribonucleosides from degraded cellular DNA. A selective inhibitor of the viral ribonucleotide reductase, 2-acetylpyridine thiosemicarbazone, decreased deoxyribonucleotide pools in infected cells, thus inhibiting viral DNA synthesis. This compound also inhibited the cellular ribonucleotide reductase to some extent, thereby enhancing its antiviral activity. The antiviral effects of acyclovir were potentiated by 2-acetylpyridine thiosemicarbazone in the wild-type virus but not in the ribonucleotide reductase mutant, ICP6 delta. Collectively, these data strongly suggest that the viral ribonucleotide reductase is an important enzyme in viral replication and a valid target for antiviral chemotherapy.

Inhibitors of thymidylate synthase and dihydrofolate reductase potentiate the antiviral effect of acyclovir

In cells infected with herpes simplex virus type 1, intracellular dNTP pools increased markedly. Treatment of these cells with 3 microM acyclovir resulted in an additional expansion in pyrimidine deoxyribonucleoside triphosphate pools with dTTP increasing 32-fold and dCTP 8-fold. Both thymidine and deoxycytidine, however, compete with acyclovir for phosphorylation by the viral pyrimidine deoxyribonucleoside kinase and thus reduce the amount of drug that is anabolized to the active form. Theoretically, agents which inhibit thymidylate synthase or dihydrofolate reductase should reduce intracellular pools of thymidine, resulting in the potentiation of the antiviral effects of acyclovir. We explored this strategy by quantitating the synergy produced by combinations of acyclovir and other drugs using three-dimensional dose-response surface methodology (MacSynergy II). Significant synergy was seen with both 5-FdUrd and methotrexate whereas BrVdUrd, 5-CldUrd, 5-IdUrd, and 5-BrdUrd exhibited little to no synergistic activity. It is suggested that inhibitors of thymidylate synthase and dihydrofolate reductase warrant further exploration as potentiators of acyclovir.

Strategic design and three-dimensional analysis of antiviral drug combinations

The development of new drugs effective against human viral diseases has proven to be both difficult and time-consuming. Indeed, there are but 10 drugs licensed for such applications in the United States today. An attractive solution to this problem may be to optimize the efficacy and selectivity of existing antiviral drugs by combining them with agents that strategically block carefully selected metabolic pathways. This approach was used in the rational design of a three-drug combination to increase the apparent potency of acyclovir against herpes simplex virus. Recent advances in analytical techniques have made the evaluation of this complex drug strategy both possible and practical. A modified version of a previously described analytical method was used to identify optimal drug concentrations and to quantitate statistically significant synergy. Concentrations of 0.25 microM 5-fluorodeoxyuridine, 3.6 microM 2-acetylpyridine thiosemicarbazone, and 0.3 microM acyclovir were determined to be optimal in terms of antiviral activity. The volume of synergy produced was nearly 2,000 microM3% at a 95% level of confidence (corresponding to a 186-fold decrease in the apparent 50% inhibitory concentration of acyclovir with the addition of 0.25 microM 5-fluorodeoxyuridine and 3.6 microM 2-acetylpyridine thiosemicarbazone). We anticipate that this strategic approach and the supporting three-dimensional analytical method will prove valuable in designing and understanding multidrug therapies.

Inhibition of cell growth and DNA, RNA, and protein synthesis in vitro by fentanyl, sufentanil, and opiate analgesics

We have studied the cytotoxic nature of two groups of narcotic analgesics. Group 1 consists of the opioids, morphine, codeine, hydromorphone, thebaine, and etorphine. Group II contains but two phenylpiperidine-type narcotics, fentanyl and sufentanil. To measure cytotoxicity, three different bioassays were employed using an established line of human cells. Specifically, the effects of narcotic analgesics on DNA, RNA, and protein synthesis were measured by following the uptake and incorporation of radiolabeled thymidine, uridine, and amino acids, respectively. Inhibition of cell growth also was studied by measuring population doubling times of logarithmically growing cells in the presence (or absence) of the test compounds. Lastly, cloning efficiencies of cells were determined in the presence of both groups of compounds. Group I compounds were significantly less inhibitory than Group II compounds by all three bioassays. Moreover, flow cytometric DNA analysis of cells treated with 100 and 320 microM etorphine HCl showed essentially no effects on cell cycle distribution. These in vitro results thus suggest that (1) fentanyl and sufentanil are inherently more cytotoxic than the opioid narcotics in Group I, and (2) the highly potent morphinoid drug etorphine HC1 appears to have special promise as a transdermal narcotic to control pain.

Three-dimensional analysis of the synergistic cytotoxicity of ganciclovir and zidovudine

The combined cytotoxicity of zidovudine and ganciclovir in three cell lines of human origin was examined. The data were generated by a new rapid cell proliferation assay and a more sensitive plating efficiency assay. A three-dimensional analytical approach was used to evaluate the drug-drug interactions, and the results were compared with those obtained by two conventional methods of analysis. Synergistic cytotoxicity was observed in all cell lines examined and by both assays. Moreover, this synergistic cytotoxicity was statistically significant at physiologically relevant concentrations. It is not known whether these drug-drug interactions manifest themselves in vivo as granulocytopenia or other untoward side effects. These results, however, indicate that further investigation is warranted and that the coadministration of zidovudine and ganciclovir may be contraindicated.

A three-dimensional model to analyze drug-drug interactions

Nearly four generations of investigators have studied combined drug effects. Their methods of generating and analyzing data have changed dramatically over the years but the basic problem has not. This review examines the inherent difficulties in analyzing combined drug effects and evaluates modern methods of describing these interactions. Researchers have traditionally used two-dimensional (2-D) methods to approximate the actual three-dimensional (3-D) nature of drug interactions. We conclude that these 2-D methods are often inadequate when used to analyze synergistic and antagonistic drug interactions in antiviral and anticancer chemotherapy. We propose a direct and pragmatic 3-D approach to the problem, made possible by microcomputers and sophisticated graphics programs. This procedure directly elucidates the shape of the dose-response surface, identifies the regions of statistically significant synergy and antagonism, and quantitates these effects. It also greatly simplifies the problem since a 3-D surface presents complete drug interactions in a way that can be easily interpreted. We will show that understanding the shape of the resulting 3-D surface is essential to an understanding of complex drug interactions. This new method facilitates the rigorous analysis of drug-drug interactions and offers investigators powerful new tools to analyze combinations of antiviral and anticancer drugs.

A microtiter virus yield reduction assay for the evaluation of antiviral compounds against human cytomegalovirus and herpes simplex virus

Although the virus yield reduction assay is a powerful technique for evaluating the efficacy of antiviral compounds, it is not routinely utilized due to its labor-intensive nature. This procedure was modified, developed, thereby reducing greatly the time and effort required to perform yield reduction assays. Monolayer cultures of mammalian cells were grown in 96-well microtiter tissue culture plates and infected with virus. Test compounds were added and serially diluted directly with the plates. Following a cycle of virus replication, culture lysates were made and serially diluted in a separate set of uninfected cultures grown in microtiter plates. The cultures were incubated, plaques were enumerated in wells containing 5 to 20 plaques, and virus titers were calculated. To illustrate the use of the assay the known antiviral drugs acyclovir and ganciclovir were evaluated using this procedure. Ninety percent inhibitory concentrations for the respective drugs were 3 microM and 0.7 microM against herpes simplex virus type 1 and 60 microM and 1 microM against human cytomegalovirus.

Influence of vehicle on topical efficacy of 2-acetylpyridine thiosemicarbazone and related derivatives on in vivo type 2 herpes simplex virus infections

2-Acetylpyridine semicarbazone (APSC), 2-acetylpyridine thiosemicarbazone (APTSC) and 2-acetylpyridine-4-methyl-3-thiosemicarbazonoe (APMTSC) were evaluated against type-2 herpes simplex virus (HSV-2)-induced genitalis and encephalitis in mice and guinea pigs. The antiviral activity of these compounds was compared with that of acyclovir. With 1,3-butanediol as a topical treatment vehicle, 1% APSC and APTSC showed significant activity against the genital infection in mice, as evidenced by increased survivors and decreased severity of vaginal lesions. Reduced titers of virus recovered from the lesions were also observed with APTSC treatments. Eight different commercially available vehicles were compared to determine in which topically administered 1% APTSC would be most efficacious against the vaginal disease induced in mice. Significant results were observed with Squibb cream base, Eucerin base, and K-Y jelly; these effects were essentially equivalent to using 1,3-butanediol Unibase, Aquaphor, polyethylene glycol, polyvinyl alcohol and petrolatum were less effective as carrier vehicles. The herpesvirus genital infection in guinea pigs was treated with 1% APMTSC and APTSC comparing Squibb cream, Eucerin and K-Y jelly bases; while neither compound exerted striking effects against this infection in any vehicle, 1% APMTSC in Squibb cream was effective in increasing mean survival time and reducing lesion score and titers of recoverable virus. In this experiment, treatments with 1 and 5% acyclovir in polyethylene glycol base were effective in reducing titers of virus from the vaginal area. Orally administered APTSC (12.5, 25, 50 mg/kg/day given twice daily for 7 days) caused moderate prevention of death of mice infected intraperitoneally with HSV-2; subcutaneous injection of the compound was markedly effective with efficacy comparable to that of acyclovir at 120 mg/kg/day.

Herpes simplex virus type 1 ribonucleotide reductase null mutants induce lesions in guinea pigs

Two herpes simplex virus type 1 ribonucleotide reductase null mutants, hrR3 and ICP6 delta, produced cutaneous lesions in guinea pigs as severe as those of wild-type strains. The lesions induced by hrR3 resulted from in vivo replication of the mutant virus, suggesting that this virus-encoded enzyme is nonessential for virus replication in guinea pigs.

Topical delivery of liposomally encapsulated interferon evaluated in a cutaneous herpes guinea pig model

The topical delivery of liposomally encapsulated interferon was evaluated in the cutaneous herpes simplex virus guinea pig model. Application of liposomally entrapped interferon caused a reduction of lesion scores, whereas application of interferon formulated as a solution or as an emulsion was ineffective. The method of liposomal preparation rather than the lipid composition of the bilayers appeared to be the most important factor for reducing lesion scores. Only liposomes prepared by the dehydration-rehydration method were effective. This finding implied that the dehydration and subsequent rehydration of the liposomes facilitate partitioning of the interferon into liposomal bilayers, where the drug is positioned for transfer into the lipid compartment of the stratum corneum. Liposomes do not appear to function as permeation enhancers but seem to provide the needed physicochemical environment for transfer of interferon into the skin.

Acceptance of hepatitis B vaccine among dental health care workers

Participation in hepatitis B vaccination programs by dental health care workers (DHCWs) has been low. Following a vaccination program at the University of Michigan School of Dentistry, a survey was conducted to determine the relation of sociodemographic status, health beliefs, amount of patient contact, and perceived barriers to participation or nonparticipation in the program by 618 students, faculty, and staff. Stepwise logistic regression revealed that a respondent's age, perceptions about susceptibility to hepatitis B, amount of patient contact, and perceptions about the cost of the vaccine were significant determinants of participation. Findings from this study suggest that a highly structured program format is necessary to lower barriers and facilitate access to vaccination, while also cueing the DHCW to appropriate preventive behavior. knowledge appears to be but one factor that may affect decisions regarding acceptance of hepatitis B vaccine; health beliefs, motivational factors, barriers, and program organization all have a significant impact on the DHCW's decision.