Changes in seismic anisotropy after volcanic eruptions: evidence from Mount Ruapehu

The eruptions of andesite volcanoes are explosively catastrophic and notoriously difficult to predict. Yet changes in shear waveforms observed after an eruption of Mount Ruapehu, New Zealand, suggest that forces generated by such volcanoes are powerful and dynamic enough to locally overprint the regional stress regime, which suggests a new method of monitoring volcanoes for future eruptions. These results show a change in shear-wave polarization with time and are interpreted as being due to a localized stress regime caused by the volcano, with a release in pressure after the eruption.

World-wide variation in HIV-1 phenotypic susceptibility in untreated individuals: biologically relevant values for resistance testing

OBJECTIVES

To examine the natural phenotypic variability in drug susceptibility among recombinant HIV-1 isolates from a large number of untreated HIV-positive individuals from wide-ranging geographic locations, and to use this information to establish biologically relevant cut-off values for phenotypic antiretroviral susceptibility testing.

METHODS

Phenotypic susceptibility to 14 antiretroviral agents was determined for HIV-1 samples from > 1000 treatment-naive individuals in seven clinical trials. Samples were from the USA (n = 351), Germany (n = 306), Canada (n = 265), and South Africa (n = 358). Geometric mean fold-resistance and confidence intervals were determined relative to a standard laboratory wild-type virus.

RESULTS

Baseline fold-resistance was approximately log-normally distributed for all antiretroviral agents examined. There was no evidence of large geographical differences in average antiviral susceptibility. Geometric mean fold-resistance for each of 14 antiviral agents was similar (+/- 0.5-fold) for samples derived from the USA, Canada, Germany, or South Africa. The non-nucleoside reverse transcriptase inhibitors (NNRTI) exhibited the broadest distribution of susceptibility; approximately 97.5% of all isolates had < 2.5-4.0, < 3.0-4.5, and < 5-10 fold-decrease in susceptibility to five protease inhibitors, six nucleoside analogues, and three NNRTI, respectively. No consistent geographic pattern or clade effect (B versus C) in either the mean or the distribution of baseline antiretroviral susceptibility was observed.

CONCLUSIONS

Phenotypic drug susceptibility of HIV-1 in untreated individuals varies markedly from drug to drug, with broadly similar patterns world-wide. These results have important implications in defining the 'normal range' of phenotypic susceptibility to antiretroviral agents and establish biologically relevant cut-off values for this phenotypic drug susceptibility test.

Clinical outcome among HIV-infected patients starting saquinavir hard gel compared to ritonavir or indinavir

OBJECTIVE

To compare the clinical response among patients who initiate protease inhibitor therapies with different virological potency.

DESIGN

We analysed patients who started indinavir, ritonavir or saquinavir hard gel capsule (hgc) as part of at least triple therapy during prospective follow-up within the EuroSIDA study.

METHODS

Changes in plasma viral load (pVL) and CD4 cell count from baseline were compared between treatment groups. Time to new AIDS-defining events and death were compared in Kaplan--Meier models, and Cox models were established to further assess differences in clinical progression (new AIDS/death). Adjustment was made for differences in baseline parameters, in particular pVL, CD4 cell count, and region of Europe.

RESULTS

A total of 2708 patients (median follow-up: 30 months) were included, of which 556 started ritonavir (21%), 1342 indinavir (50%), and 810 saquinavir hgc (30%). The three groups were fairly evenly balanced at baseline regarding CD4 count, previous diagnosis of AIDS and pVL, After 12 months, the median changes in CD4 cell count were 90, 96 and 74 x 10(6) cells/l, respectively;P < 0.001, the proportions of patients with pVL < 500 copies/ml were 47, 54 and 41%; P < 0.001, and the proportions with clinical progression were 11.9, 9.2 and 11.9%, respectively; P = 0.20 (log-rank test). In multivariate models the relative risk of clinical progression for indinavir compared with saquinavir hgc was: 0.77 (0.60--0.99); P = 0.043, and for ritonavir 0.83 (0.62--1.11); P = 0.20.

CONCLUSIONS

Saquinavir hgc was associated with an inferior long-term clinical response relative to indinavir, which was consistent with the observed differences in virological and immunological responses.

Quality of life in inflammatory bowel disease: a cross-cultural comparison of English and Canadian children

BACKGROUND

Any disease and its treatment has an important impact on health-related quality of life for affected individuals. There have been few previous studies on the quality of life for children with inflammatory bowel disease (IBD).

METHODS

A cross-cultural comparison was performed to determine whether the concerns of children with IBD in the United Kingdom are ranked similarly to those of children with IBD in Canada. An item reduction questionnaire, developed from interviews with Canadian children with IBD, was scored by 53 British children with IBD for importance and frequency, as a questionnaire had been scored previously by 117 Canadian children.

RESULTS

There was a significant correlation between the mean scores (r = 0.831, P < 0.001) and ranks (r = 0.801, P < 0.001) for the 96 questions, and 43 of the 50 highest-ranking concerns corresponded for both populations. Confidence interval analysis showed a significant difference between the mean values for 21 of the 96 items; 20 of these 21 were ranked higher in the United Kingdom than they had been in Canada, suggesting that the frequency and/or degree of concern was greater for the British children with IBD.

CONCLUSIONS

Health-related concerns of British children with Crohn disease and ulcerative colitis correlate closely with those of Canadian children with those diseases. Further studies are needed to determine the sensitivity of individual questions, the most appropriate wording of these questions, and the optimal length for a proposed instrument to assess quality of life in children with IBD.

Antiviral activity of tenofovir (PMPA) against nucleoside-resistant clinical HIV samples

The presence of the lamivudine-associated M184V RT mutation increases tenofovir susceptibility in multiple HIV genotypes. Tenofovir is uniquely active against multinucleoside-resistant HIV expressing the Q151M mutation, but shows reduced susceptibility to the T69S insertion mutations. HIV with common forms of zidovudine and lamivudine resistance are susceptible to tenofovir, corroborating phase II clinical results demonstrating the activity of tenofovir DF in treatment-experienced patients.

Laboratory guidelines for the practical use of HIV drug resistance tests in patient follow-up

HIV drug resistance is one of the major limitations in the successful treatment of HIV-infected patients using currently available antiretroviral combination therapies. When appropriate, drug susceptibility profiles should be taken into consideration in the choice of a specific combination therapy. Guidelines recommending resistance testing in certain circumstances have been issued. Many clinicians have access to resistance testing and will increasingly use these results in their treatment decisions. In this document, we comment on the different methods available, and the relevant issues relating to the clinical application of these tests. Specifically, the following recommendations can be made: (i) genotypic and phenotypic HIV-1 drug resistance analyses can yield complementary information for the clinician. However, insufficient information currently exists as to which approach is preferable in any particular clinical setting; (ii) when HIV-1 drug resistance testing is required, it is recommended that testing be performed on plasma samples obtained before starting, stopping or changing therapy, on samples that have a viral load above the detection limit of the resistance test; (iii) the panel recommends that genotypic and phenotypic HIV-1 drug resistance testing for clinical purposes be performed in a certified laboratory under strict quality control and quality assurance standards; and (iv) the panel recommends that resistance testing laboratories provide clinicians with resistance reports that include a list of drug-related resistance mutations (genotype) and/or a list of drug-related fold resistance values (phenotype), with interpretations of each by an experienced virologist. The interpretation of genotypic and phenotypic analysis is a complex and developing science, and in order to understand HIV-1 drug resistance reports, communication between the requesting clinician and the expert that interpreted the resistance report is recommended.

International perspectives on antiretroviral resistance. Resistance to protease inhibitors

The availability of protease inhibitors (PIs) and their combination with nucleoside reverse transcriptase inhibitors marked the passage of antiretroviral therapy (ART) from potential for control to effective suppression and thus substantially reduced rates of morbidity and mortality related to HIV. Even so, what was first hoped to be an immutable HIV DNA treatment target has proved to be prone to resistance mutations, with substitutions identified at more than 20 amino acid sites, which reduces PI susceptibility and increases resistance to treatment. The mutation patterns associated with each PI have been defined, and have been observed to occur at one of two locations: at or near the active site, or in the substrate cleavage site. The natural history of PI resistance has been extensively studied, and the genetic and cellular pathways are described in detail in this article. In addition, cross-resistance among PIs is now recognized to be fairly extensive, although the degree of cross-resistance varies with the number of mutations and the variants selected by drug pressure. Thus, it is still possible to salvage a response with another PI after a first regimen with another PI has failed. The extensive basic science and clinical experience with PIs in the fight against HIV are reviewed in this article, which provides data on resistance-mutation profiles, cellular resistance mechanisms, viral fitness studies, and clinical outcome trials with various first-line and subsequent regimens that contain PIs. It is hoped that the information provided will guide physicians in best using PIs as part of a logical and successful ART strategy.

Inhaled aerosolization of all-trans-retinoic acid for targeted pulmonary delivery

Retinoids have shown promising activity for both cancer chemoprevention and as a treatment for emphysema. However, chronic oral administration of these drugs is limited by systemic side effects, including hepatic dysfunction, skeletal malformations, hyperlipidemia. hypercalcemia, and other reactions. In order to improve the pulmonary targeting of this potentially useful therapy, we developed a system for aerosolization of retinoids that substantially increased their local bioavailability. We compared the biodistribution and pharmacokinetics of an inhaled formulation of all-trans-retinoic acid (all-trans-RA), which was packaged in a metered dose inhaler, following both intratracheal (IT) and intravenous (IV) administration in male Sprague-Dawley rats. After drug administration, anesthetized animals were killed at 5 min, and at 1, 2, 4, 6 and 24 h. Plasma and emulsified samples of liver and lung tissues were dissected, extracted, and frozen prior to measurement of all-trans-RA concentration by high-performance liquid chromatography (HPLC). Aerosolization and IT injection of all-trans-RA resulted in a significantly longer pulmonary half-life of the drug (both 5-17 h), lower peak serum concentrations (aerosol 71 +/- 31 ng/ml, IT 68 +/- 50 ng/ml), and lower liver levels (aerosol 111 +/- 28 ng/g, IT 753 +/- 350 ng/g) than the same dose administered IV (2 h, 838 +/- 56 ng/ml, 4,258 +/- 1,006 ng/g, respectively; P < 0.05 for each comparison). Histologic examination of lungs and trachea showed no focal irritation attributable to the drug after single-dose administration. These results suggest that aerosolization of retinoids may offer a practical alternative to systemic oral administration for chemoprevention trials or treatment of lung diseases. This method may substantially increase the therapeutic index of these compounds by reducing systemic complications associated with long-term dosing.

Structured treatment interruptions in antiretroviral management of HIV-1

The consequences of treatment interruptions have been investigated in various patient populations. For patients with controlled viraemia, treatment interruption allowing viral rebound may boost HIV-1-specific immunity. The hypothesis that this will be sufficient to control HIV replication in the absence of treatment has received support in studies of patients initiating treatment during primary infections. In patients with chronic infection, treatment interruption has been shown to boost HIV-1-specific immunity in some cases. In patients with virological failure, despite drug-resistant virus, treatment appears to provide benefit, in that interruption results in a decrease in the CD4 cell count and increases in plasma HIV-1-RNA levels. The removal of drug pressure allows the rapid shift to wild-type virus. Whether this will be of benefit to the patient is not clear. Treatment interruption may help reduce the accumulation of long-term toxicities.

Challenging the platinum combinations: docetaxel (Taxotere) combined with gemcitabine or vinorelbine in non-small cell lung cancer

The limited single-agent activity of cisplatin, its toxicity profile, and the inconvenience involved in hydrating patients has compelled researchers to investigate other treatments as possible alternative therapies in non-small cell lung cancer. More recently, interest has focused on the potential of nonplatinum combinations. Phase II studies show that the combination of docetaxel (Taxotere; Aventis, Antony, France) and gemcitabine is active in stage IIIB/IV non-small cell lung cancer not previously treated by chemotherapy. Response rates of up to 54% and a median survival time of 13 months have been reported. These data are comparable with the achievements of cisplatin-based combinations. A randomized phase II trial of docetaxel plus gemcitabine versus docetaxel plus cisplatin found that the two regimens were equally active in terms of response rate, median, and 1-year survival. However, the combination of docetaxel with gemcitabine produced significantly less neutropenia and nonhematologic toxicities. In combination, from 80% to 100% of the full single-agent gemcitabine and docetaxel doses can safely be administered once every 3 weeks. The combination of docetaxel plus vinorelbine is also active in non-small cell lung cancer and preliminary data suggest that this schedule with prophylactic filgrastim may optimize tolerability and dose intensity. In a phase II study using this approach, a confirmed response rate of 51% was obtained in 35 patients. At 12 months, the predicted median survival is 14 months and the predicted 1-year survival rate is 60%. Excessive lacrimation, fatigue, and onycholysis were cumulative toxicities. However, the incidence of mucositis and neuropathy was low with the combination of docetaxel and vinorelbine. Docetaxel combined with other new agents, particularly gemcitabine, may offer another useful alternative to cisplatin-based chemotherapy in patients with good performance status.

The use of and response to second-line protease inhibitor regimens: results from the EuroSIDA study

OBJECTIVE

To describe the use of second line protease-inhibitor (PI) regimens across Europe and to determine factors associated with virological and immunological response.

DESIGN

Analysis of data from 984 patients with a median follow-up of 21 months enrolled in EuroSIDA. Patients started their second PI-containing regimen at least 16 weeks after starting the first PI-containing regimen and with viral load > 1000 copies/ml.

METHODS

Virological response was defined as a viral load < 500 copies/ml and immunological response as an increase of 50 x 10(6)/l or more in CD4 lymphocyte count.

RESULTS

The median CD4 cell count at starting the second PI was 171 x 10(6) cells/l; viral load was 4.45 log copies/ml. As a second PI regimen, 45% were using a dual PI, while of those on one PI, indinavir (42%) and nelfinavir (34%) were most common. In multivariate Cox models, a higher viral load at starting the second PI [relative hazard (RH), 0.67 per 1 log higher; 95% confidence interval (CI), 0.58-0.77; P < 0.0001) and a lower CD4 cell count (RH, 1.15 per 50% higher; 95% CI, 1.06-1.26; P = 0.0014) were associated with a reduced probability of virological response. Those who had achieved viral suppression on the first PI-regimen were more likely to respond to the second (RH, 1.65; 95% CI, 1.30-2.10; P < 0.0001) as were those who added one or two new nucleosides to their second PI.

CONCLUSIONS

Patients who initiate a second PI regimen at lower viral load, higher CD4 cell count or who added new nucleosides tended to be more likely to achieve a viral load < 500 copies/ml. The roles of cross-resistance and adherence in response to second-line regimens needs further investigation.

The virological response to highly active antiretroviral therapy over the first 24 weeks of therapy according to the pre-therapy viral load and the weeks 4-8 viral load

OBJECTIVES

To describe the viral response to HAART by weeks 4 and 8 in previously antiretroviral-naive patients. To assess whether the weeks 4 or 8 viral loads are useful predictors of viral suppression by week 24.

DESIGN

A large clinical database including 453 antiretroviral-naive patients whose plasma viral load was monitored every 4 weeks.

METHODS

Observed probabilities of achieving a viral load < or = 500 copies/ml by week 24 (days 84-168) from starting highly active antiretroviral therapy (HAART) were calculated according to viral loads at weeks 4 and 8.

RESULTS

A total of 42.4% of patients (153/361) reached < or = 500 copies/ml viral load by week 4 and 70.4% (245/348) by week 8. Viral suppression below 500 copies/ml by 4-8 weeks was similar irrespective of the pre-HAART viral load. In patients with viral loads above 10000 copies/ml at week 4, 60.6% (20/33) achieved < or = 500 copies/ml by week 24. In patients with viral loads still above 10000 copies/ml at week 8, only 42.3% (11/26) achieved < or = 500 copies/ml by week 24, and only 33.3% (3/9) maintained viral suppression below 500 copies/ml to week 48.

CONCLUSION

Viral loads at weeks 4 and 8 should be monitored to detect early signs of low subsequent viral suppression. For previously antiretroviral-naive patients whose viral loads after 8 weeks of HAART are still above 10000, there is an urgent need to assess adherence to therapy, drug levels and resistance, so management can be modified accordingly to reduce the rate of week 24 virological failure.

Laboratory Guidelines for the Practical Use of HIV Drug Resistance Tests in Patient Follow-Up

HIV drug resistance is one of the major limitations in the successful treatment of HIV-infected patients using currently available antiretroviral combination therapies. When appropriate, drug susceptibility profiles should be taken into consideration in the choice of a specific combination therapy. Guidelines recommending resistance testing in certain circumstances have been issued. Many clinicians have access to resistance testing and will increasingly use these results in their treatment decisions. In this document, we comment on the different methods available, and the relevant issues relating to the clinical application of these tests. Specifically, the following recommendations can be made: (i) genotypic and phenotypic HIV-1 drug resistance analyses can yield complementary information for the clinician. However, insufficient information currently exists as to which approach is preferable in any particular clinical setting; (ii) when HIV-1 drug resistance testing is required, it is recommended that testing be performed on plasma samples obtained before starting, stopping or changing therapy, on samples that have a viral load above the detection limit of the resistance test; (iii) the panel recommends that genotypic and phenotypic HIV-1 drug resistance testing for clinical purposes be performed in a certified laboratory under strict quality control and quality assurance standards; and (iv) the panel recommends that resistance testing laboratories provide clinicians with resistance reports that include a list of drug-related resistance mutations (genotype) and/or a list of drug-related fold resistance values (phenotype), with interpretations of each by an experienced virologist. The interpretation of genotypic and phenotypic analysis is a complex and developing science, and in order to understand HIV-1 drug resistance reports, communication between the requesting clinician and the expert that interpreted the resistance report is recommended.

Virological and immunological effects of treatment interruptions in HIV-1 infected patients with treatment failure

OBJECTIVE

To analyse the immunological and virological effects of treatment interruptions in HIV-1-infected patients with treatment failure and multidrug-resistant virus.

METHODS

Drug susceptibility was assessed using Antivirogram and genotypic analysis was based on population and clonal sequencing for 48 patients who had interrupted treatment (> or = 2 months).

RESULTS

Treatment interruption resulted in viral load increases (mean 0.7 log 10 copies/ ml; P = 0.0001) and CD4 cell count decreases (mean 89 x 10(6) cells/l; P = 0.0001). A complete shift to wild-type virus at the phenotypic, genotypic and clonal level was observed in 28/45 patients. These patients differed from those that did not show a shift to wild type in baseline CD4 cell counts (192 versus 59 x 10(6) cells/l; P= 0.007) and in the relationship between baseline viral load and CD4 cell count (no correlation versus a significant negative correlation; P= 0.008). Response to re-initiation of treatment fell with increasing viral load [relative hazard (RH) 0.33; P= 0.001] and with increasing total number of drugs with reduced susceptibility (RH 0.51; P = 0.0003); it improved with the number of new drugs received (RH 2.12; P = 0.0002) and a shift to wild type (RH 5.22, P = 0.006).

CONCLUSIONS

Changes in surrogate markers suggest that treatment provided benefit in spite of virological failure and resistant virus. Although patients with a shift to wildtype virus responded better in the short term to treatment re-initiation, the long-term effects are not known and the risk of immune deterioration needs to be carefully considered.

Human motor development and hand laterality: a kinematic analysis of drawing movements

This study examines the developmental profiles of basic 'open-loop' drawing movements on the non-dominant hand (ND) in comparison with the dominant hand (D). Fifty-three right-handed children aged 7-14 years and 15 adults aged 27-43 years were examined. Each subject drew lines and circles of different sizes at maximum velocity with a pressure-sensitive pen on a computer graphics tablet. Small lines were drawn at 90 degrees to the axis of the forearm (lines using wrist movements (LWM)) and along the axis of the forearm (lines using elbow movements (LEM)). Larger lines were drawn at 90 degrees to the axis of the forearm (LEM). At both extremities, the movement frequencies of the proximally generated drawing movements increased in a parallel fashion at different levels. In LWM, the right-left-differences (RLD) were high in 7- to 8-year-old children; until puberty, the ND hand reached almost the performance of the D hand. In contrast, the RLD of the LFM increased at the same time. As adulthood approaches, frequencies of all drawings increased further while the LWM on the ND side remained stable. In adults, there were similar RLD for all line drawings involving predominantly flexion and extension movements. When drawing circles, the RLD were highest, though stable in all age groups. Hand laterality of pen use changes over time; these changes are dependent on complexity (combined/sequential cf. flexion-extension muscle activation) and on topography (proximal cf. distal movements). Distinct developmental profiles of motoneuronal populations of the cortex may be responsible for the distinct hand laterality effects and the decreasing variability of motor patterns. The drawing abilities and developmental changes on the untrained ND hand indicate that effector-specific practice plays a minor role.

The influence of attitudes about unintended pregnancy on use of prenatal and postpartum care

OBJECTIVE

The purpose of this study was to examine the effects of feelings about pregnancy and consideration of abortion on late initiation of prenatal care and postpartum appointment.

STUDY DESIGN

A descriptive study was conducted in a tertiary clinic in Detroit using a convenience sample comprised of 518 low-income pregnant and postpartum women with a large number of unintended pregnancies. A series of chi-square analyses and logistic regression models were conducted to identify variables predictive of these outcomes.

RESULTS

Teenagers were 1.8 times more likely to initiate late prenatal care versus early care (p = 0.05), and women who considered an abortion were 3.7 times more likely to initiate late prenatal care (p = 0.01). Having considered abortion but deciding against it due to psychologic/moral reasons was protective against late initiation of prenatal care (OR = 0.23; p = 0.01). Multiparity was the only predictor of a missed postpartum appointment. Multiparous women were three times more likely to miss the appointment (p = 0.05).

CONCLUSIONS

Success in improving early access to prenatal care will involve addressing the issue of unintended pregnancy. This challenge will require that health care providers assess feelings and values related to a pregnancy. Understanding women's feelings and values about the pregnancy will allow providers to more effectively assist with decision-making and positive pregnancy behaviors. In addition, community-based education related to family planning and the value of prenatal and postpartum care is needed to involve women's partners, family, and friends, because social support systems influence decisions regarding pregnancy behaviors.

Neonatal cerebral infarction

Neonatal cerebral infarction in term infants has many possible causes, including bacterial meningitis, inherited or acquired coagulopathies, trauma, and hypoxia-ischemia. However, a specific cause often cannot be identified. Neurologic symptoms in the neonatal period are often subtle and nonspecific, even in infants with large infarctions involving an entire cerebral artery distribution. The most common presenting symptom is focal motor seizures of the contralateral limbs. Cranial magnetic resonance imaging, especially with diffusion-weighting, is the most sensitive imaging modality, although ultrasonography with Doppler imaging of cerebral blood flow is useful in the neonate who is too ill to transport. Neurodevelopmental outcome is often surprisingly good, with many infants making a complete recovery of motor function. The effect of neonatal stroke on cognitive function, especially language acquisition and emotional and social development, has not been fully established.

The impact of protease inhibitor-containing highly active antiretroviral therapy on progression of HIV disease and its relationship to CD4 and viral load

OBJECTIVE

To compare the rate of disease progression according to viral load and CD4 cell count in patients receiving or not receiving highly active antiretroviral therapy (HAART), defined as protease inhibitor-containing regimens.

DESIGN

An observational study, with prospectively collected data.

METHODS

All patients attending the HIV Outpatient clinic as of 1 January 1995 (n = 2083) were included. Follow-up was until the first AIDS-defining event or death. Associations between viral load or CD4 cell count and disease progression were assessed using a person-years approach. Event rates were compared using Poisson regression analysis; a multivariate model was used to assess the independent effects of CD4, viral load and treatment group on event rates and to consider interactions between these variables.

RESULTS

The event rates increased with lower CD4 cell count and higher viral load for both treatment groups and were generally lower in the HAART group. In a multivariate analysis, lower CD4 cell counts and higher viral loads remained significantly associated with disease progression, irrespective of treatment group. However, the event rate was significantly lower for the HAART group compared with the control group (relative rate 0.53, P < 0.001).

CONCLUSIONS

HAART-treated patients with high viral loads and CD4 cell counts experienced reduced disease progression compared with individuals with the same CD4 cell count and viral load not receiving HAART. Consequently, the short-term prognosis associated with viral load levels and CD4 cell counts may differ in patients on HAART. Whether this effect will be observed with non-protease-inhibitor-containing HAART is not known at this time.

Costs of smoking during pregnancy: development of the maternal and child health smoking attributable mortality, morbidity and economic costs (MCHSAMMEC) software

The development and availability is described of new, user friendly software, the Maternal and Child Health Smoking Attributable Mortality, Morbidity and Economic Costs (MCHSAMMEC), that will allow states and other entities to estimate pregnancy related, smoking attributable costs for their population. The methodology underlying the MCHSAMMEC software, including calculations used in the prevalence based analysis of smoking attributable mortality and costs of infant neonatal care, are described, along with design and data management features and possible applications of the software for policy and program development at various levels of the health care system.

Determinants of parental decisions after the prenatal diagnosis of down syndrome: bringing in context

This article develops the concept of decision context to refer to the combinations of factors that are important in understanding and predicting termination decisions after a prenatal diagnosis of trisomy 21. Four factors are examined: maternal age, gestational age, prior voluntary abortion, and existing children. The cases were studied at the Wayne State University's Reproductive Genetics Clinic. Qualitative comparative analysis, a technique specifically designed for examining the impact of combinations of factors, is used to isolate influential decision contexts. Odds and odds ratios are used to pinpoint outcome differences among different decision contexts. Four alternative decision contexts are especially conducive to choosing to terminate a pregnancy. Two of these involve women of any age and are formed from combinations of gestational age and existing children (existing children and low gestational age, and no children combined with late gestational age). Older women who have not had an abortion and who discover the trisomy 21 anomaly early are likely to choose termination. Younger women who have had an abortion are also likely to choose termination. Our data suggest there are added layers of complexity to patients' decisions that derive from combinations of conditions. An additional, strong implication is that qualitative comparative analysis may be particularly useful in understanding such complexity.

Activity of cellular thymidine kinase 1 in PBMC of HIV-1-infected patients: novel therapy marker

Cellular cytoplasmatic thymidine kinase 1 (TK1) catalyzes the intracellular phosphorylation of anti-HIV-1 nucleoside analogs zidovudine (AZT) and stavudine (d4T) to the corresponding monophosphate form. In HIV-1-infected patients, treated with combination therapy including one of these compounds for more than 1 year, enzymatic activity of TK1 in peripheral blood mononuclear cells (PBMC) was determined by radioactive assay. TK1 activity in PBMC of HIV-1-infected patients correlated with CD4 cell count (r = 0.4, p<0.05) and HIV-1 RNA copy number (r = 0.4, p<0.05), being lower in patients with decreased CD4 cell count and high viral load. Furthermore,TK1 activity differs between HIV-1-infected individuals treated for more than 6 months (13.5 pmol/mg/h) compared to patients treated for less than 6 months (28.1 pmol/mg/h; p<0.05) with chemotherapeutic agents including thymidine analogs. The results demonstrate that TK1 deficiency in PBMC of HIV-1 infected patients may develop due to continuous treatment with thymidine analogs and correlates with a more progressed stage of disease expressed as diminished CD4 cell count and increased viral load.