Effectiveness of the booster dose of COVID-19 vaccine in the Basque Country during the sixth wave: A nationwide cohort study

The aim of the study was to assess the effect of a booster dose of COVID-19 vaccine on the rates of hospital ward and intensive care unit (ICU) admissions around the time of emergence of the Omicron variant in the Basque Country. A retrospective cohort population-based study was conducted. The population with any records related to COVID-19 vaccination up to 28 February 2022 was classified into four cohorts by vaccination status. For every cohort, the hospital ward and ICU admission rates were calculated for each day between November 2021 and February 2022. Generalized linear models with a negative binomial distribution were used to estimate the age-adjusted hospitalization rate ratio of the cohort of individuals who had received a booster compared to the other cohorts. The age-adjusted rates of hospital ward and ICU admissions were 70.4 % and 72.0 % lower, respectively, in the fully vaccinated plus booster group compared to the fully vaccinated but no booster group. Analysing changes in the 14-day admission incidence rates showed that as the prevalence of the Omicron variant increased, the corresponding rate ratios decreased. The immunity acquired with the booster dose allowed the hospital network to meet all the demand for hospitalization during a period of high incidence of COVID-19, despite the fact that vaccine protection decreased as the prevalence of the Omicron variant increased.

Brief cognitive tests as a decision-making tool in primary care. A population and validation study

INTRODUCTION AND OBJECTIVES

Brief cognitive tests (BCT) are used in primary care (PC) for the detection of cognitive impairment (CI). Still, there are little data on their diagnostic utility (DU) in a community setting. This work evaluates the DU at the population level of Fototest, T@M, AD8 questionnaire and MMSE. It provides new cut-off points (CoP) validated in a CI early detection program.

MATERIAL AND METHODS

In the population and validation samples, the evaluation was carried out in two phases, a first of screening and administration of BCT and a second of clinical diagnosis, blinded to the results of the BCT, applying the current NIA-AA criteria. The DU of BCT in the population sample was evaluated with the area under the ROC curve (aROC). Youden index and the CoP with the best specificity that ensured a sensitivity of 80% were used to decide on the most appropriate CoP. The sensitivity, specificity, and predictive values for these CoP were calculated in the validation sample.

RESULTS

260 participants (23.1% with CI) from the population sample and 177 (42.4% with CI) from the validation sample were included. The Fototest has the best UD at the population level (aROC 0.851), which improves with the combination of Fototest and AD8 (aROC 0.875). The proposed CoP are AD8 ≥ 1, Fototest ≤ 35, T@M ≤ 40, and MMSE ≤ 26.

CONCLUSION

BCT are helpful in detecting CI in PC. This work supports the use of more demanding PoC.

Validity of a computerised population registry of dementia based on clinical databases

INTRODUCTION

The handling of information through digital media allows innovative approaches for identifying cases of dementia through computerised searches within the clinical databases that include systems for coding diagnoses. The aim of this study was to analyse the validity of a dementia registry in Gipuzkoa based on the administrative and clinical databases existing in the Basque Health Service.

METHODS

This is a descriptive study based on the evaluation of available data sources. First, through review of medical records, the diagnostic validity was evaluated in two samples of cases identified and not identified as dementia. The sensitivity, specificity and positive and negative predictive value of the diagnosis of dementia were measured. Subsequently, the cases of living dementia in December 31, 2016 were searched in the entire Gipuzkoa population to collect sociodemographic and clinical variables.

RESULTS

The validation samples included 986 cases and 327 no cases. The calculated sensitivity was 80.2% and the specificity was 99.9%. The negative predictive value was 99.4% and positive value was 95.1%. The cases in Gipuzkoa were 10 551, representing 65% of the cases predicted according to the literature. Antipsychotic medication were taken by a 40% and a 25% of the cases were institutionalised.

CONCLUSIONS

A registry of dementias based on clinical and administrative databases is valid and feasible. Its main contribution is to show the dimension of dementia in the health system.

Validity of a computerized population registry of dementia based on clinical databases

INTRODUCTION

The handling of information through digital media allows innovative approaches for identifying cases of dementia through computerized searches within the clinical databases that include systems for coding diagnoses. The aim of this study was to analyze the validity of a dementia registry in Gipuzkoa based on the administrative and clinical databases existing in the Basque Health Service.

METHODS

This is a descriptive study based on the evaluation of available data sources. First, through review of medical records, the diagnostic validity was evaluated in 2 samples of cases identified and not identified as dementia. The sensitivity, specificity and positive and negative predictive value of the diagnosis of dementia were measured. Subsequently, the cases of living dementia in December 31, 2016 were searched in the entire Gipuzkoa population to collect sociodemographic and clinical variables.

RESULTS

The validation samples included 986 cases and 327 no cases. The calculated sensitivity was 80.2% and the specificity was 99.9%. The negative predictive value was 99.4% and positive value was 95.1%. The cases in Gipuzkoa were 10,551, representing 65% of the cases predicted according to the literature. Antipsychotic medication were taken by a 40% and a 25% of the cases were institutionalized.

CONCLUSIONS

A registry of dementias based on clinical and administrative databases is valid and feasible. Its main contribution is to show the dimension of dementia in the health system.

Evaluation of the colorectal cancer screening Programme in the Basque Country (Spain) and its effectiveness based on the Miscan-colon model

Abstract

The population-based Basque Colorectal Cancer (CRC) Screening Programme started in 2009 with a biennial immunochemical quantitative test (FIT) biennial and colonoscopy under sedation in positive cases. The population target of 586,700 residents was from 50 to 69 years old and the total coverage was reached at the beginning of 2014. The aim of our study was to determine possible scenarios in terms of incidence, mortality and reduction of Life-years-Lost (L-y-L) in the medium and long term of CRC.

Methods

Invitations were sent out by the Programme from 2009 to 2014, with combined organizational strategies. Simulation was done by MISCAN-colon (Microsimulation Screening Analysis) over 30 years comparing the results of screening vs no-screening, taking the population-based Cancer Registry into account. Lifetime population and real data from the Programme were used from 2008 to 2012. The model was run differentially for men and women.

Results

924,416 invitations were sent out from 2009 to 2014. The average participation rate was 68.4%, CRC detection rate was 3.4% and the Advanced Adenoma detection rate was 24.0‰, with differences observed in sex and age. Future scenarios showed a higher decrease of incidence (17.2% vs 14.7%), mortality (28.1% vs 22.4%) and L-y-L (22.6% vs 18.4%) in men than women in 2030.

Conclusions

The Basque Country CRC Programme results are aligned to its strategy and comparable to other programmes. MISCAN model was found to be a useful tool to predict the benefits of the programme in the future. The effectiveness of the Programme has not been formally established as case control studies are required to determine long term benefits from the screening strategy.

Advanced prostate cancer survival in Spain according to the Gleason score, age and stage

OBJECTIVES

The aim of this study was to determine the overall and disaggregated survival based on the Gleason score, age and extent of a patient cohort diagnosed with advanced prostate cancer according to standard clinical practice.

MATERIAL AND METHOD

We used an observational and retrospective design for the study. For each patient, we recorded clinical variables such as the extent (metastatic or locally advanced), Gleason score, age, date of diagnosis, date of last contact with the health system and the vital status during the last contact. We used univariate and multivariate statistical techniques of survival. The parametric survival methods enabled us to calculate the mean survival using extrapolation. We analysed 219 patients treated in the public health system between 2008 and 2011. The analysis showed statistically significant differences in survival depending on Gleason score, age and stage. The longest survival was in the subgroup younger than 75 years, with a local extent and a low-risk category on the Gleason scale (19.41 years), and the shortest survival (0.97 years) was in the 75 years or older group. The survival of the other subgroups ranged between these outliers.

CONCLUSION

The main contribution of this study is that it is the first to calculate the mean survival of advanced prostate cancer in Spain in terms of the variables of our study population. This information helps clinicians predict the life expectancy of each patient according to their prognostic factors.

Regional variability in changes in the incidence of hip fracture in the Spanish population (2000-2012)

The objective is to analyse the evolution of the incidence of hip fracture in the female population of Spain from 2000 to 2012 and to establish the possible changes which may have been seen over this period of time, including the trends in the different regions of the country.

INTRODUCTION

Fragility-related hip fractures are considered to be the fractures of greatest significance to public health due to their high degree of morbidity and mortality. The change in their incidence, both in absolute values and when adjusted for age, is the subject of debate. The objective of this article is to describe the changes in the rates of hip fracture in Spain by autonomous community between the years 2000 and 2012.

METHODS

Using the data from the Spanish Minimum Basic Data Set, in which are all the recorded cases of women with a principal diagnosis of hip fracture, the incidence rates by age group and by autonomous community were obtained. Poisson distribution or negative binomial regressions were carried out to estimate the average annual change over the time period analysed.

RESULTS

There have been statistically significant changes in the trends of rates of incidence for all age groups of women over 65 years of age. The annual reduction was 2.2% for women of 65-74 years of age and less for those between 75 and 84. The rates of incidence for those over 85 increased annually by 0.58%.

CONCLUSIONS

Hip fractures continue to increase in absolute numbers, although if the rates are adjusted for age, a downward trend is seen in certain age groups. These findings have various origins, although in the absence of great changes in population structure, we believe that drug treatments for osteoporosis may play a role. There is variability in the change in incidence of hip fractures in different parts of the country. Further studies are required to be able to identify the causes.

Cost analysis of real-time polymerase chain reaction microbiological diagnosis in patients with septic shock

Antibiotic treatment for septic shock is generally prescribed on an empirical basis using broad-spectrum antibiotics. Molecular diagnostic techniques can detect the presence of microbial DNA in blood within a few hours and facilitate early, targeted treatment. The aim of this study was to evaluate the economic impact of a real-time polymerase chain reaction technique, LightCycler SeptiFast (LSC), in patients with sepsis. A cost-minimisation study was carried out in patients admitted with a diagnosis of severe sepsis or septic shock to the intensive care unit of a university hospital. The stay in the intensive care unit, hospital admission, 28-day and six-month mortality, and the economic cost of the clinical process were also evaluated. The study involved 48 patients in the LSC group and 54 patients in the control group. The total cost was €42,198 in the control group versus €32,228 in the LCS group with statistically significant differences (P <0.05), giving rise to an average net saving of €9970 per patient. The mortality rate was similar in both groups. The main finding of this study was the significant economic saving afforded by the use of the LCS technique, due to the shortening of intensive care unit stay and the use of fewer antibiotics.

Role of health-related quality of life measurements in the design of drug clinical trials

OBJECTIVE

Health-related quality of life (HRQL) measurements enable us to take patient perception into account when evaluating treatment outcomes from clinical trials (CTs). The purpose of this study was to evaluate the use of HRQL questionnaires as a measurement of efficacy in CT design.

METHODS

A duplicate systematic review of the CTs examined by a Clinical Research Ethics Committee between 1995 and 2006 was performed to check for use of HRQL. We gathered data concerning general aspects including medical specialty, drugs evaluated, methodological quality and inclusion of economic variables. For CTs including HRQL measurements, we analysed the type of questionnaire in use. Where there were no HRQL measurements, we analysed the methodological possibilities for including them, and the relevance of their absence.

RESULTS

A total of 242 CTs were analysed; 69 (28.5%) included HRQL measurements, and 10 CTs (4.1%) used them as a primary endpoint. Only 22 CTs used more than one questionnaire. Data analysis by therapeutic area showed that HRQL was most commonly studied in the fields of rheumatology, urology, psychiatry and oncology. Only 33 CTs included economic variables.

CONCLUSIONS

Measurements based on clinical parameters are the most commonly used means of measuring efficacy. Only a small percentage of CTs take the patient's perception of his/her health into account, despite the increasing importance given to this parameter. Including HRQL questionnaires in CTs design is still far from common.

[Assessment of acute postoperative pain]

OBJECTIVE

A nursing task is to look after the pain associated with surgical procedures in order to maintain patient wellbeing. The first objective of this study was to measure the level of the patient satisfaction with management of post-operative pain. Secondly, we wanted to identify the determining factors of an adequate postoperative analgesia and the predictive value of the visual analogical scale (VAS).

MATERIAL AND METHODS

A sample of patients who had an operation was interviewed. The VAS was administered two hours and 24h after the surgical procedure with the American Society of Pain questionnaire. ROC curves were applied to establish the cut-off point for the VAS. We determined the contribution of different variables to adequate pain management by means of logistic regression.

RESULTS

We interviewed 237 patients in 2007 and 2008. Pain during the first 24h was perceived by 54% of them, 98% were satisfied with pain management and 95% expressed that analgesic treatment relieved their pain. Variables statistically associated with pain were specialty, and a value on the VAS higher than 0 two hours after the procedure.

CONCLUSIONS

The management of post operative pain is satisfactory. The use of the VAS during the first two hours identifies an important percentage of patients who require more intensive analgesic treatment.

Unmet needs for cataract surgery in Spain according to indication criteria. Evaluation through a simulation model

AIMS

Despite the increase in cataract surgery rates, the volume of unmet needs for this type of surgery in the population is substantial due to ageing and widening of the indication criteria. Our objective was to assess future trends in needs for cataract surgery according to different scenarios of indication criteria.

METHODS

A discrete-event simulation model was built for the population aged 50 years or older in five regions of Spain (45.7% of the population). Different scenarios of worse eye visual acuity thresholds for indication criteria were compared. Data from the North London Eye Study were used to project the baseline needs for surgery onto the study population. The surgery rate of each region was calculated using the Minimum Data Set. The model used data for the year 2003 and the simulation horizon was 5 years.

RESULTS

The volume of need predicted for the year 2008 when scenarios of 0.5 (20/40) and 0.4 (20/50) visual acuity thresholds were used was 69,214 and 51,315 surgeries needed per million inhabitants, respectively. However, unmet needs decreased when a 0.3 (20/70) threshold was used. The increment in the cataract surgery rate needed to prevent the cataract backlog from increasing was 60% for a 0.5 threshold and 50% for a 0.4 threshold.

CONCLUSION

Application of indication criteria following current guidelines would substantially increase unmet needs for surgery in the next 5 years.

[The cost of cerebrovascular accident]

INTRODUCTION AND AIM

One out of three persons will die of cerebrovascular accident (CVA), another one will be disabled, and the third one will recover. This research has been taken to estimate the costs of CVA in the Basque Country.

MATERIALS AND METHODS

The cost of illness is studied from a societal perspective. It is based on the prevalence of the disease. Population costs has been estimated from the use of resources of a randomized sample of patients admitted to hospital with stroke during the year 2000, and followed for 12 months. Transitions costs (those that happen just once) and state costs (those remaining in patients lifetime) have been studied separately.

RESULTS

The prevalence of CVA was 1.780 x 10(5). Average transition cost per patient was 4,762 euros and average state cost for patient/year was 10,506 euros. The estimated cost for the Basque Country is 120,249,986 euros in the year 2000. Transition costs were 16,460,729 euros and state costs 103,789,257 euros in the same year. State costs were due to disability.

CONCLUSIONS

The analysis of the costs of CVA from a societal perspective gets us to the heart of illness causing disability, the social costs of CVA are 74.3% of the total cost.

[Hospital care of cerebrovascular accident and the state of patients 12 months after]

OBJECTIVES

Cerebrovascular accident should be of key importance due to its magnitude in terms of mortality and disability. In this study we describe hospital care of patients and follow them one year after. The aims is to uncover areas of improvement in the care of patients.

PATIENTS AND METHODS

Observational study of a randomized sample of 535 patient with a diagnosis of cerebrovascular disease, during de acute phase and 12 months after, using clinical records and telephone interview.

RESULTS

Thirty five percent of patients arrived within 6 hours of the occurrence of the event. Thirty six percent had a CAT/MNR within 6 hours. Mortality at hospital was 13.8% increasing up to 26% at 12 months. At discharge 49% had a neurological deficiency. At 12 months 35.8% of the survivors interviewed showed a Barthel Index of less than 95 points.

CONCLUSIONS

Organizational measures that guarantee a quick and systematic assessment of brain lesions, early diagnosis and active therapeutic offer, have to be implemented. In the sample studied, only 3% of the patient were candidates to thrombolytic therapy. Rehabilitation can and should play a more relevant role in the prevention of sequelae.

[The availability in Spanish public hospitals of resources for diagnosing and treating sleep apnea-hypopnea syndrome]

INTRODUCTION AND OBJECTIVE

Sleep apnea-hypopnea syndrome is associated with an overall deterioration in the patients health and affects between 1 and 2 million people in Spain. The objective of the present study was to evaluate the diagnostic and therapeutic resources available in Spain for dealing with this problem in terms of both infrastructure and human resources.

METHODS

We selected 461 general hospitals, 457 (99.1%) of which answered a questionnaire in the course of a telephone interview.

RESULTS

At the time of response, 219 hospitals (47.5%) reported performing sleep studies. Conventional polysomnography was available in 53% of those hospitals, respiratory polygraphy was used in 42%, and oximetry in 5%. In 47% of the hospitals, continuous positive airway pressure was titrated empirically in most cases; the number of patients being treated with CPAP was 109,752, that is, 269 per 100,000 population in Spain.

CONCLUSIONS

The level of resources available for diagnosing and treating sleep apnea-hypopnea syndrome, although improving, is clearly still inadequate. Currently, only 0.49 polysomnograph and 0.72 polygraph machines are available per 100,000 population, whereas 1 and 3 machines, respectively, are deemed necessary. Only 5% to 10% of the affected population has been diagnosed, and in 47% of the hospitals interviewed continuous positive airway pressure is not properly titrated. These results should be a clarion call to the health authorities to take the appropriate steps to address this health problem.

Cost-effectiveness analysis of therapeutic strategies for patients with chronic hepatitis C previously not responding to interferon

BACKGROUND

The efficacy of combination therapy in patients with chronic hepatitis C previously not responding to interferon monotherapy is lower than that in naive patients, and there has been no economic evaluation in this population.

AIM

To develop a cost-effectiveness analysis of therapeutic regimens with interferon-alpha and ribavirin in previous interferon non-responders.

METHODS

A Markov simulation model was used to project the clinical and economic outcomes of five different therapeutic strategies, including a 'no treatment' alternative, using the health care system perspective. The efficacy data for the different doses and durations were obtained from a previously performed meta-analysis. A sensitivity analysis was performed to test the robustness of the model, analysing changes in different variables.

RESULTS

Applying a 3% discount rate, the standard patient on combination therapy for 12 months showed increases of 0.80 years and 1.55 quality-adjusted life years, when compared with the 'no treatment' strategy. This option led to an incremental cost-effectiveness ratio of 11,767 euros per year of life gained and 6073 euros per quality-adjusted life year.

CONCLUSIONS

Combination therapy with interferon plus ribavirin is cost-effective in previous interferon non-responders and is within the range of some well-accepted medical interventions in our health care system.

The cost-effectiveness of nCPAP treatment in patients with moderate-to-severe obstructive sleep apnoea

The demand for diagnostic and therapeutic services for obstructive sleep apnoea syndrome (OSAS) showed marked growth during the 1990s. This paper analyses the long-term cost-effectiveness of nasal continuous positive airway pressure (nCPAP) treatment in comparison to conventional null treatment. A Markov model was used to represent the natural history of OSAS based upon published evidence. Utility values came from a survey of OSAS patients. Data on health costs were collected from hospitals in the Basque Country, Spain. The incremental cost-effectiveness ratio of nCPAP treatment is <6,000 Euros per quality-adjusted life year. On disaggregated analysis, nCPAP treatment accounts for 86% of incremental costs; 84% of incremental effectiveness is attributable to improved quality of life. Treatment of obstructive sleep apnoea syndrome with nasal continuous positive airway pressure has a cost-effectiveness that is in line with that of other commonly funded treatments such as antihypertensive drugs. The key clinical benefit of nasal continuous positive airway pressure treatment is improvement in the quality of life of patients with obstructive sleep apnoea syndrome. This benefit is also precisely the one for which the evidence base is strongest. The remaining uncertainties concerning the impact of nasal continuous positive airway pressure on long-term mortality have only a relatively small impact on the economics of treatment.

Mutational analysis of the Menkes copper P-type ATPase (ATP7A)

The Menkes protein (ATP7A; MNK) is a ubiquitous human copper-translocating P-type ATPase and it has a key role in regulating copper homeostasis. Previously we characterised fundamental steps in the catalytic cycle of the Menkes protein. In this study we analysed the role of several conserved regions of the Menkes protein, particularly within the putative cytosolic ATP-binding domain. The results of catalytic studies have indicated an important role of 1086His in catalysis. Our findings provide a biochemical explanation for the most common Wilson disease-causing mutation (H1069Q in the homologous Wilson copper-translocating P-type ATPase). Furthermore, we have identified a unique role of 1230Asp, within the DxxK motif, in coupling ATP binding and acylphosphorylation with copper translocation. Finally, we found that the Menkes protein mutants with significantly reduced catalytic activity can still undergo copper-regulated exocytosis, suggesting that only the complete loss of catalytic activity prevents copper-regulated trafficking of the Menkes protein.

The regulation of catalytic activity of the menkes copper-translocating P-type ATPase. Role of high affinity copper-binding sites

The Menkes protein is a transmembrane copper translocating P-type ATPase. Mutations in the Menkes gene that affect the function of the Menkes protein may cause Menkes disease in humans, which is associated with severe systemic copper deficiency. The catalytic mechanism of the Menkes protein, including the formation of transient acylphosphate, is poorly understood. We transfected and overexpressed wild-type and targeted mutant Menkes protein in yeast and investigated its transient acyl phosphorylation. We demonstrated that the Menkes protein is transiently phosphorylated by ATP in a copper-specific and copper-dependent manner and appears to undergo conformational changes in accordance with the classical P-type ATPase model. Our data suggest that the catalytic cycle of the Menkes protein begins with the binding of copper to high affinity binding sites in the transmembrane channel, followed by ATP binding and transient phosphorylation. We propose that putative copper-binding sites at the N-terminal domain of the Menkes protein are important as sensors of low concentrations of copper but are not essential for the overall catalytic activity.

Which is more important for the efficiency of hypertension treatment: hypertension stage, type of drug or therapeutic compliance?

OBJECTIVES

Hypertensive patients are a heterogeneous population that can be distributed in groups showing different cardiovascular risk and benefit from treatment. This study examines the cost-effectiveness of arterial hypertension treatment by age, sex, arterial hypertension stage, type of drug used and level of treatment compliance.

DESIGN

Markov models combining absolute risks for stroke, coronary heart disease and all causes of death with relative risks from clinical trials and observational studies. Data on health costs were collected from hospitals and primary care settings in the Basque Country (Spain).

RESULTS

Cost-effectiveness ratios vary from 34,516 euros/quality adjusted life year (QALY) gained in 30-year-old women to 3,307 euros/QALY in 80-year-old men. A treatment compliance of 50% increases these values to 45,270 and 4,905 euros/QALY, respectively. Treatment of arterial hypertension stage II shows lower ratios (19,798 euros/QALY in 30-year-old women and 1,918 euros/QALY in 80-year-old persons). Cost-effectiveness ratios for arterial hypertension stage I vary from 645 euros/QALY in 80-year-old men for diuretics to 47,325 euros/QALY in 30-year-old women for inhibitors of the angiotensin converting enzyme.

CONCLUSIONS

There are large variations in the cost-effectiveness of arterial hypertension treatment depending on age, sex, arterial hypertension stage, drug used and compliance. Improvement of treatment compliance yields the greatest gain both in effectiveness and efficiency.

[Costs analysis of ambulatory blood pressure monitoring in mild hypertension]

BACKGROUND

To contrast the costs of conventional and ambulatory blood pressure monitoring (ABPM) methods in the diagnosis, treatment and follow-up of mild hypertensive patients.

METHODS

Among patients with conventional diagnosis of mild hypertension, the ABPM would discriminate patients with sustained hypertension, who would receive drug treatment, from patients with white coat hypertension (WCH), who would be only followed up. The diagnosis, treatment and control costs were obtained from 446 mild hypertensive patients from the Primary Health Care Center Aranbizkarra II (Vitoria, Spain) during 1996. For each gender, the overall costs per patient were estimated in both conventional and ABPM methods in terms of mean diagnosis age and WCH percentage.

RESULTS

For 45 years old patients and 30% of WCH, the overall costs per patient among men were 414,999 and 371, 101 pesetas with conventional and ABPM methods, respectively. From 30 to 60 years old patients, the ABPM method turned up to be less expensive as long as the WCH percentage was higher than 6%. Similar results were obtained among women with mild hypertension.

CONCLUSIONS

ABPM can be accepted as an useful clinical tool for the screening of patients with conventional diagnosis of mild hypertension. On the one hand, ABPM allows to select patients with low cardiovascular risk (WCH). On the other hand, the savings resulting from treatment reduction and fewer physician visits are higher than the additional costs of ABPM recordings.

Targeted mutation of plasma phospholipid transfer protein gene markedly reduces high-density lipoprotein levels

It has been proposed that the plasma phospholipid transfer protein (PLTP) facilitates the transfer of phospholipids and cholesterol from triglyceride-rich lipoproteins (TRL) into high-density lipoproteins (HDL). To evaluate the in vivo role of PLTP in lipoprotein metabolism, we used homologous recombination in embryonic stem cells and produced mice with no PLTP gene expression. Analysis of plasma of F2 homozygous PLTP-/- mice showed complete loss of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, and partial loss of free cholesterol transfer activities. Moreover, the in vivo transfer of [3H]phosphatidylcholine ether from very-low-density proteins (VLDL) to HDL was abolished in PLTP-/- mice. On a chow diet, PLTP-/- mice showed marked decreases in HDL phospholipid (60%), cholesterol (65%), and apo AI (85%), but no significant change in non-HDL lipid or apo B levels, compared with wild-type littermates. On a high-fat diet, HDL levels were similarly decreased, but there was also an increase in VLDL and LDL phospholipids (210%), free cholesterol (60%), and cholesteryl ester (40%) without change in apo B levels, suggesting accumulation of surface components of TRL. Vesicular lipoproteins were shown by negative-stain electron microscopy of the free cholesterol- and phospholipid-enriched IDL/LDL fraction. Thus, PLTP is the major factor facilitating transfer of VLDL phospholipid into HDL. Reduced plasma PLTP activity causes markedly decreased HDL lipid and apoprotein, demonstrating the importance of transfer of surface components of TRL in the maintenance of HDL levels. Vesicular lipoproteins accumulating in PLTP-/- mice on a high-fat diet could influence the development of atherosclerosis.

Ambulatory blood pressure monitoring and diagnostic errors in hypertension: a Bayesian approach

Random variability of blood pressure complicates the diagnosis and subsequent treatment of hypertension. To evaluate the importance of the number of blood pressure measurements in the correct diagnosis and control of hypertension, the authors used a Bayesian model to estimate the true average blood pressure of a group of newly diagnosed hypertensives, then calculated the diagnostic error that would result from monitoring methods using 24 daytime measurements or from using only three random monitoring measurements. The study population consisted of 129 individuals with newly diagnosed mild hypertension according to standard criteria, who were also evaluated with an ambulatory blood pressure monitor. In true normotensives (daytime diastolic blood pressure <90 mm Hg), the negative predictive value with three measurements was 0.92, and it rose to 0.96 with monitoring methods. In mild hypertensives (90-104 mm Hg), the positive predictive value was 0.64 with three measurements and 0.84 with monitoring methods, thus reducing the rate of false mild hypertensives from 35% to 15%. Finally, in patients with moderate or severe hypertension (>104 mm Hg), the positive predictive value improved from 0.26 with three readings to 0.61 with monitoring methods. Similar results were observed with daytime systolic pressure measurements. As the number of measurements increased, the diagnostic error due to the random variability of blood pressure became progressively smaller. In cases of hypertension, the large improvement in predictive values may justify using monitoring methods to confirm standard diagnosis.

Expression of plasma phospholipid transfer protein mRNA in normal and emphysematous lungs and regulation by hypoxia

The lung is the major site expressing plasma phospholipid transfer protein (PLTP) mRNA in humans and mice, suggesting that this protein might have an important role in maintaining normal function of this organ. In the lung of human collagenase transgenic mice, an emphysematous animal model, PLTP mRNA was 3-fold higher than in control mice. However, the mRNA in other tissues was not changed. To further assess the expression and function of PLTP, we measured PLTP mRNA level in lung tissue of two emphysematous patients and found that the mRNA was 4-fold higher than in control subjects. In situ hybridization on mouse lung suggested positive staining in alveolar type II epithelial cells. In addition, immortalized rat alveolar pre-type II epithelial cells and freshly isolated mature rat alveolar type II epithelial cells both highly expressed PLTP mRNA, and the former cells actively secreted PLTP activity into the medium. To examine the possible mechanisms leading to high levels of PLTP expression in vivo, we exposed the pre-type II cells to hypoxia and demonstrated induction of PLTP mRNA and a coordinate increase in secreted PLTP activity. Thus, the PLTP gene is highly expressed in alveolar type II epithelial cells and is induced during hypoxia and in emphysema. These observations suggest that a hypoxic stimulus occurring in emphysema may be a novel mechanism that contributes to enhanced expression of PLTP.

Increased prebeta-high density lipoprotein, apolipoprotein AI, and phospholipid in mice expressing the human phospholipid transfer protein and human apolipoprotein AI transgenes

Human plasma phospholipid transfer protein (PLTP) circulates bound to high density lipoprotein (HDL) and mediates both net transfer and exchange of phospholipids between different lipoproteins. However, its overall function in lipoprotein metabolism is unknown. To assess the effects of increased plasma levels of PLTP, human PLTP transgenic mice were established using the human PLTP gene driven by its natural promoter. One line of PLTP transgenic mice with moderate expression of PLTP mRNA and protein was obtained. The order of human PLTP mRNA expression in tissues was: liver, kidney, brain, small intestine > lung > spleen > heart, adipose tissue. Western blotting using a human PLTP monoclonal antibody revealed authentic human PLTP (Mr 80 kD) in plasma. Plasma PLTP activity was increased by 29% in PLTP transgenic mice. However, plasma lipoprotein analysis, comparing PLTP transgenic mice to control littermates, revealed no significant changes in the plasma lipoprotein lipids or apolipoproteins. Since previous studies have shown that human cholesteryl ester transfer protein and lecithin:cholesterol acyltransferase only function optimally in human apoAI transgenic mice, the human PLTP transgenic mice were cross-bred with human apoAI transgenic mice. In the human apoAI transgenic background, PLTP expression resulted in increased PLTP activity (47%), HDL phospholipid (26%), cholesteryl ester (24%), free cholesterol (37%), and apoAI (22%). There was a major increase of apoAI in prebeta-HDL (56%) and a small increase in alpha-HDL (14%). The size distribution of HDL particles within alpha- and prebeta-migrating species was not changed. The results suggest that PLTP increases the influx of phospholipid and secondarily cholesterol into HDL, leading to an increase in potentially antiatherogenic prebeta-HDL particles.

Down-regulation of mRNA for the low density lipoprotein receptor in transgenic mice containing the gene for human cholesteryl ester transfer protein. Mechanism to explain accumulation of lipoprotein B particles

To evaluate the effects of cholesteryl ester transfer protein (CETP) on apoB-containing lipoproteins, we analyzed plasma lipoproteins from three different lines of human CETP transgenic mice, with plasma CETP concentration ranging from low (1.5 microgram/ml) to high levels (8.5 micrograms/ml). With increasing CETP concentration, very low density lipoprotein and low density lipoprotein (LDL) cholesteryl ester (CE) and apoB were progressively increased, and high density lipoprotein CE was decreased. To investigate the mechanism of accumulation of lipoproteins containing apoB (lipoprotein B), the abundance of hepatic LDL receptor mRNA was determined. LDL receptor mRNA was reduced as a result of CETP expression, with maximum repression to about 48% of the level of non-transgenic mice. Among the different lines of CETP transgenic mice there was an inverse relationship between plasma CETP concentration and hepatic LDL receptor mRNA abundance (r = -0.94, p < 0.01). CETP expression also led to increased cholesterol and cholesteryl ester content in liver and to decreased abundance of mRNAs encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductase and 7-alpha-hydroxylase. Thus, CETP expression results in increased cholesteryl ester concentration in very low density lipoprotein and LDL, probably reflecting both CE transfer from high density lipoprotein and accumulation of lipoprotein B particles. The accumulation of lipoprotein B particles results from CETP-mediated down-regulation of liver LDL receptors, possibly due to enhanced return of cholesterol to the liver.

New poly(A)+RNAs appear coordinately during the differentiation of Naegleria gruberi amebae into flagellates

We have examined the nature of the requirement for RNA synthesis during the differentiation of Naegleria gruberi amebae into flagellates (Fulton, C., and C. Walsh, 1980, J. Cell Biol., 85:346-360) by looking for poly(A)+RNAs that are specific to differentiating cells. A cDNA library prepared from poly(A)+RNA extracted from cells 40 min after initiation of the differentiation (40-min RNA), the time when formation of flagella becomes insensitive to inhibitors of RNA synthesis, was cloned into pBR322. Recombinant clones were screened for sequences that were complementary to 40-min RNA but not to RNA from amebae (0-min RNA). Ten of these differentiation-specific (DS) plasmids were identified. The DS plasmids were found to represent at least four different poly(A)+RNAs based on cross-hybridization, restriction mapping, and Northern blot analysis. Dot blot analysis was used to quantify changes in DS RNA concentration. The four DS RNAs appeared coordinately during the differentiation. They were first detectable at 10-15 min after initiation, reached a peak at 70 min as flagella formed, and then declined to low levels by 120 min when flagella reached full length. The concentration of the DS RNAs was found to be at least 20-fold higher in cells at 70 min than in amebae. The changes in DS RNA concentration closely parallel changes in tubulin mRNA as measured by in vitro translation (Lai, E.Y., C. Walsh, D. Wardell, and C. Fulton, 1979, Cell, 17:867-878).

A dangerous error in Fluothane packaging

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