Treatment of primary human immunodeficiency virus type 1 infection with potent antiretroviral therapy reduces frequency of rapid progression to AIDS

Immunologic data supporting immediate antiretroviral therapy in primary human immunodeficiency virus type 1 (HIV-1) infection are emerging; however, clinical benefit has not been demonstrated. The clinical and virologic course of 47 patients who were enrolled from September 1993 through June 1996 and who were not initially treated with potent therapy was compared with the course of 20 patients who immediately began therapy with zidovudine, lamivudine, and indinavir. Demographic and baseline laboratory data were comparable. During 78 weeks of follow-up, the early-treatment cohort showed a reduced frequency of opportunistic infections (5% vs. 21.3%; relative risk, 0.11; P=.02), less frequent progression to AIDS (13% vs. 0%), and significantly less frequent nonopportunistic mucocutaneous disorders and respiratory infections (P<.01). Plasma HIV-1 RNA levels were <50 copies/mL in all patients who continued therapy; however, after 9--12 months, HIV-1 remained detectable in latently infected CD4(+) T cells and in lymph node mononuclear cells. Combination antiretroviral therapy during primary HIV-1 infection demonstrated a decreased frequency of minor opportunistic infections, mucocutaneous disorders, and respiratory infections and reduced progression to AIDS.

Endosymbiotic sulphate-reducing and sulphide-oxidizing bacteria in an oligochaete worm

Stable associations of more than one species of symbiont within a single host cell or tissue are assumed to be rare in metazoans because competition for space and resources between symbionts can be detrimental to the host. In animals with multiple endosymbionts, such as mussels from deep-sea hydrothermal vents and reef-building corals, the costs of competition between the symbionts are outweighed by the ecological and physiological flexibility gained by the hosts. A further option for the coexistence of multiple symbionts within a host is if these benefit directly from one another, but such symbioses have not been previously described. Here we show that in the gutless marine oligochaete Olavius algarvensis, endosymbiotic sulphate-reducing bacteria produce sulphide that can serve as an energy source for sulphide-oxidizing symbionts of the host. Thus, these symbionts do not compete for resources but rather share a mutalistic relationship with each other in an endosymbiotic sulphur cycle, in addition to their symbiotic relationship with the oligochaete host.

Urinary tract infection in adults: research priorities and strategies

Waning interest in urinary tract infection (UTI) research has limited clinical advances during the past two decades. Although care has improved for some specific UTI syndromes, there is limited evidence for most of the decisions made each day in the management of these infections. Additional clinical research is necessary to improve UTI prevention and care strategies.

Productive infection of T cells in lymphoid tissues during primary and early human immunodeficiency virus infection

Current models suggest that during human immunodeficiency virus type 1 (HIV-1) transmission virions are selected that use the CCR5 chemokine receptor on macrophages and/or dendritic cells. A gradual evolution to CXCR4 chemokine receptor use causes a shift in the proportion of productively infected cells to the CD4 cell population. Productively infected cells during acute and early infection in lymphoid tissue were assessed, as well as the impact of productive infection on the T cell population in 21 persons who had biopsies performed on days 2-280 after symptoms of acute HIV-1 seroconversion. Even in the earliest stages of infection, most productively infected cells were T lymphocytes. There were sufficient infected cells in lymphoid tissue (LT) to account for virus production and virus load in plasma. Despite the relatively high frequency of productively infected cells in LT, the impact on the size of the T cell population in LT at this stage was minor.

[Myoclonus in the adult: diagnostic approach]

Myoclonus, defined as shock-like involuntary movement, may be physiological or caused by a very wide variety of hereditary and acquired conditions. Because myoclonus can originate from different disorders and lesions affecting quite varied levels of the central and peripheral nervous systems, it represents from many points of view a diagnostic challenge. Moreover, new entities have been recently individualized, such as cortical tremor, which deserve renewed attention. The aim of this review is to propose a rationale for a diagnostic approach based on clinical and electrophysiological grounds. In this setting, we successively address 1) the clinical features allowing a positive diagnosis of myoclonus; 2) the clinical clues to the etiology; 3) the relevance of the clinical context to the diagnosis; and 4) the contribution of neurophysiology. Differentiating myoclonus from tics, spasm, chorea and dystonia can be difficult, and a careful reappraisal of clinical features allowing precise identification is presented. Moreover, the topographical distribution of myoclonus, the temporal pattern of muscle recruitment, the condition of occurrence and the rhythm of the event, may provide clinical clues relevant to the diagnosis. Myoclonus without associated epilepsy, myoclonus with epilepsy, myoclonus with encephalopathy, parkinsonism and/or dementia represent overlapping clinical categories, although they remain useful for the diagnostic approach. Using electrophysiology (including back-averaging EEG, MEG, SEP, C-reflex studies) to determine the origin of myoclonus may not allow us to focus on the underlying condition. Indeed, in many instances, the myoclonus is cortical in origin, but the pathology is found elsewhere.

Cost-effectiveness of combined outreach for the pneumococcal and influenza vaccines

BACKGROUND

We conducted a cost-effectiveness analysis as part of a randomized, controlled trial of a community-based outreach initiative to promote the pneumococcal and influenza vaccines for people aged 65 years or older.

METHODS

The analysis was based on primary data from the trial on the increase in vaccination rates and cost of the intervention, and published estimates of the effectiveness of the vaccines and cost of treatment. We performed partial stochastic analyses based on the confidence intervals (CIs) of the effectiveness of the intervention and of the vaccines.

RESULTS

The cost-effectiveness ratio of the combined-outreach initiative as implemented was $35 486 per quality-adjusted life-year (QALY), whereas it was $53 547 per QALY for the pneumococcal vaccine and $130 908 per QALY for the influenza vaccine. In partial stochastic analyses, the quasi-CI of the combined-outreach initiative ranged from $15 145 to $152 311 per QALY. The cost-effectiveness ratio of the intervention targeted to people who had never received the pneumococcal vaccine or who had not received the influenza vaccine in the previous year was $11 771 per QALY, with a quasi-CI of $3330 to $46 095 per QALY. With the use of the projected cost of replicating the intervention, the cost-effectiveness ratio was $26 512 per QALY for the initiative as implemented and $7843 per QALY for a targeted initiative.

CONCLUSIONS

The community-based outreach initiative to promote the pneumococcal and influenza vaccines was reasonably cost-effective. Further improvements in cost-effectiveness could be made by targeting the initiative or through lessons learned during the first year that would reduce the cost of the initiative in subsequent years.

Urinary tract infection in childhood

Over the past year, research about urinary tract infections in childhood has yielded new data about methods to detect, treat, and evaluate children who develop urinary tract infection. New imaging modalities have been studied. Long term studies following children with urinary tract infection have also been published over the last year. However, major questions remain to be answered, including the underlying basis of host-pathogen interactions in the urinary tract, as well as the most effective methods for clinical diagnosis and management.

[A device for mandibular advancement in respiratory disorders of sleep. Clinical study]

This study describes the technical steps for the making of a mandibular advancement device for sleep disordered patients (apnea index < 10). In a second part of the study, a group of 21 patients with sleep disordered breathing treated successfully with a mandibular advancement device is compared to a homologous control group. The experimental group showed cephalometric characteristics approaching those seen in patients with sleep apnea syndrome. The mandibular advancement device moved the mandibule forward (SNB angle increases by 1.7 degrees) and downward (mandibular plane angle increases by 3 degrees, which can be related to the 7.4 mm anterior vertical height increase). The hyoid bone adopted a more distant position from the cervical vertebrae. Important individual variations were seen among the patients for the optimal repositioning of the mandible.

Purification and molecular cloning of chemosensory proteins from Bombyx mori

Soluble low molecular weight acidic proteins are suspected to transport stimulus molecules to the sensory neurons within insect sensilla. From the antennae of Bombyx mori, we have purified and sequenced a protein (BmorCSP1) bearing sequence similarity to a class of soluble chemosensory proteins recently discovered in several orders of insects. Based on its N-terminal sequence, the cDNA encoding this protein has been amplified and cloned. Differential screening of a B. mori antennal cDNA library led to the identification of a second gene encoding a related protein (BmorCSP2), sharing 35-40% identity to BmorCSP1 and chemosensory proteins from other species. The predicted secondary structures of moth's, chemosensory proteins comprise alpha-helical foldings at conserved positions and a reduced hydrophobicity with respect to this novel family of chemosensory proteins.

Phylogenetic relationships of the North American sturgeons (order Acipenseriformes) based on mitochondrial DNA sequences

The evolutionary relationships of the extant species within the order Acipenseriformes are not well understood. Nucleotide sequences of four mitochondrial genes (12S rRNA, COII, tRNA(Phe), and tRNA(Asp) genes) in North American sturgeon and paddlefish were examined to reconstruct a phylogeny. Analysis of the combined gene sequences suggests a basal placement of the paddlefish with regard to the sturgeons. Nucleotide sequences of all four genes for the three Scaphirhynchus species were identical. The position of Scaphirhynchus based on our data was uncertain. Within the genus Acipenser, the two Acipenser oxyrinchus subspecies were very similar in sequence and found to be basal to the remaining Acipenser species examined. Based on our data, Acipenser transmontanus and Acipenser medirostris were sister taxa, as were Acipenser fulvescens and Acipenser brevirostrum. Comparison of our results with hypotheses of sturgeon relationships proposed by previous authors is presented. The sequence data presented here are phylogenetically useful and provide a solid foundation of genetic information for the North American Acipenseriformes that can be expanded to include Eurasian species to provide a global picture of sturgeon evolution.

Clinical approach to excessive daytime sleepiness

Subjective sleepiness is defined as "an elemental feeling state" by which the subject, and only him/her knows whether he/she is alert or sleepy. Subjective sleepiness has little been used for the clinical evaluation of sleepiness. Objective sleepiness is defined as a consequence of the homeostatic need for sleep. In the absence of a measurable marker of the fulfillment of the function of sleep, the evaluation of objective sleepiness has to rely on a behavioral approach based on the postulate that the more you need sleep (i.e., the sleepier you are), the more likely you are to fall asleep. However, as for many other fundamental human behaviors (drinking, eating, sexual behavior), it is likely that the sleeping behavior serves other purposes than its primary objective, which distorts the relationship between the observed sleeping behavior and the actual need for sleep. The likelihood to fall asleep can be measured by the speed with which a sleep episode occurs under standardized laboratory conditions (multiple sleep latency test, maintenance of wakefulness test, OSLER test), or by the frequency of unwanted sleep episodes under the more naturalistic conditions of daily life (Epworth Sleepiness Scale). These various approaches have advantages and drawbacks, but none of them can be considered the "gold standard".

Cyclic adenosine monophosphate signaling in the rat vomeronasal organ: role of an adenylyl cyclase type VI

The present study indicates that male rat urinary components in female rat vomeronasal organ microvillar preparations not only induce a rapid and transient IP(3) signal, but in addition, the level of cAMP decreases with a delayed and sustained time course. This decrease seems to be a consequence of the preceding activation of the phosphoinositol pathway rather than the result of an enhanced phosphodiesterase activity or an inhibition of adenylyl cyclase (AC) via Galpha(i) or Galpha(o). This notion is supported by the finding that activation of the endogenous protein kinase C suppresses basal as well as forskolin-induced cAMP formation. Furthermore, it was observed that elevated levels of calcium inhibit cAMP formation in rat VNO microvillar preparations. These properties of cAMP signaling in the VNO of rats may be mediated by a calcium- and protein kinase C-inhibited AC VI subtype, which is localized in microvillar preparations of the VNO.

Three pheromone-binding proteins in olfactory sensilla of the two silkmoth species Antheraea polyphemus and Antheraea pernyi

Females of the sibling silkmoth species Antheraea polyphemus and A. pernyi use the same three sex pheromone components in different ratios to attract conspecific males. Accordingly, the sensory hairs on the antennae of males contain three receptor cells sensitive to each of the pheromone components. In agreement with the number of pheromones used, three different pheromone-binding proteins (PBPs) could be identified in pheromone-sensitive hairs of both species by combining biochemical and molecular cloning techniques. MALDI-TOF MS of sensillum lymph droplets from pheromone-sensitive sensilla trichodea of male A. polyphemus revealed the presence of three major peaks with m/z of 15702, 15752 and 15780 and two minor peaks of m/z 15963 and 15983. In Western blots with four antisera raised against different silkmoth odorant-binding proteins, immunoreactivity was found only with an anti-(Apol PBP) serum. Free-flow IEF, ion-exchange chromatography and Western blot analyses revealed at least three anti-(Apol PBP) immunoreactive proteins with pI values between 4.4 and 4.7. N-Terminal sequencing of these three proteins revealed two proteins (Apol PBP1a and Apol PBP1b) identical in the first 49 amino acids to the already known PBP (Apol PBP1) [Raming, K. , Krieger, J. & Breer, H. (1989) FEBS Lett. 256, 2215-2218] and a new PBP having only 57% identity with this amino-acid region. Screening of antennal cDNA libraries with an oligonucleotide probe corresponding to the N-terminal end of the new A. polyphemus PBP, led to the discovery of full length clones encoding this protein in A. polyphemus (Apol PBP3) and in A. pernyi (Aper PBP3). By screening the antennal cDNA library of A. polyphemus with a digoxigenin-labelled A. pernyi PBP2 cDNA [Krieger, J., Raming, K. & Breer, H. (1991) Biochim. Biophys. Acta 1088, 277-284] a homologous PBP (Apol PBP2) was cloned. Binding studies with the two main pheromone components of A. polyphemus and A. pernyi, the (E,Z)-6, 11-hexadecadienyl acetate (AC1) and the (E,Z)-6,11-hexadecadienal (ALD), revealed that in A. polyphemus both Apol PBP1a and the new Apol PBP3 bound the 3H-labelled acetate, whereas no binding of the 3H-labelled aldehyde was found. In A. pernyi two PBPs from sensory hair homogenates showed binding affinity for the AC1 (Aper PBP1) and the ALD (Aper PBP2), respectively.

Chemosensory proteins of Locusta migratoria (Orthoptera: Acrididae)

We describe a family of proteins abundantly expressed in the chemoreception sensory organs, the antennae and legs, of the desert locust, Locusta migratoria (Orthoptera, Acrididae). Using polymerase chain reaction-based approaches and homology screenings, "OS-D"-like proteins were identified in L. migratoria. The different sub-types (LmigOS-Ds) are very similar to each other and share about 50-70% identity with OS-Ds from Drosophila melanogaster and Periplaneta americana. A similar degree of identity was also observed with moth OS-Ds. Northern blot analysis revealed a strong expression of the LmigOS-Ds in the antennae and legs, suggesting their involvement in chemosensory processes. Despite the lack of direct evidence for their role in chemosensation, LmigOS-Ds and their homologs seem to constitute a large protein family, characterized by a striking abundance and diversity among insect chemosensory organs.

Upper airway collapsibility and cephalometric variables in patients with obstructive sleep apnea

Increased pharyngeal collapsibility and abnormal anatomic structures have been postulated to contribute to the pathophysiology of obstructive sleep apnea (OSA) syndrome. It is unclear whether the abnormal craniofacial and soft tissue features may affect the pharyngeal collapsibility and contribute to the apnea density. In the present study we examine the relationship between pharyngeal collapsibility and cephalometric variables in a group of 57 male OSA patients. Pharyngeal collapsibility was measured during the night of nasal continuous positive airway pressure (nCPAP) titration by analyzing the pressure-flow relationship. Pharyngeal critical pressure (Pcrit) was calculated as the extrapolated pressure at zero flow. The patients, age 52.0 +/- 9.0 yr, had an average apnea-hypopnea index (AHI) of 72.6 +/- 31.8 and a mean Pcrit of 2.4 +/- 1.0 cm H(2)O. A significant correlation was found between Pcrit and the soft palate length (SPl) (r = 0.27, p = 0.04), the distance from the hyoid bone to the posterior pharyngeal wall (H-Ph) (r = 0. 29, p = 0.03), and the distance from the hyoid bone to posterior nasal space (H-Pns) (r = 0.32, p = 0.02). While in obese patients Pcrit was related to SPl and neck circumference, the distance of the hyoid bone to the mandibular plane (H-MP) affected Pcrit in nonobese patients. Our results show that both pharyngeal soft tissue abnormalities and the lower position of the hyoid bone affect Pcrit in OSA patients, suggesting that an anatomic narrowing contributes to the upper airway collapsibility.

Rapid accumulation of human immunodeficiency virus (HIV) in lymphatic tissue reservoirs during acute and early HIV infection: implications for timing of antiretroviral therapy

The follicular dendritic cell network (FDC) in lymphoid tissues (LTs) is the major site of human immunodeficiency virus (HIV) storage in presymptomatic and late stages of disease. However, little is known about the rate of virus accumulation during the acute and early stages. In situ hybridization and quantitative image analysis were used to determine the amount of virus bound to the FDC network during the first year of infection. The FDC pool was already >7.0 log10 copies of HIV RNA/g LT in the first year, and 2 patients biopsied within 2-4 days of symptom onset had 7.3 and 8.2 log10 copies of HIV RNA/g LT, respectively. There was no correlation between duration of infection and accumulation of HIV into the FDC network. These data suggest that a large pool of infectious virus is established soon after infection and that initiation of antiretroviral therapy when symptoms of primary HIV infection are recognized is unlikely to prevent substantial accumulation of virus in the FDC network.

Olfactory reception in invertebrates

Recent progress in understanding the principles and mechanisms in olfaction is the result of multidisciplinary research efforts that explored chemosensation by using a variety of model organisms. Studies on invertebrates, notably nematodes, insects, and crustaceans, to which diverse experimental approaches can be applied, have greatly helped elucidate various aspects of olfactory signaling. From the converging results of genetic, molecular, and physiological studies, a common set of chemosensory mechanisms emerges. Recognition and discrimination of odorants as well as chemo-electrical transduction and processing of olfactory signals appear to be mediated by fundamentally similar mechanisms in phylogenetically diverse animals. The common challenge of organisms to decipher the world of odors was apparently met by a phylogenetically conserved strategy. Thus, comparative studies should continue to provide important contributions toward an understanding of the sense of smell.

Effective compliance during the first 3 months of continuous positive airway pressure. A European prospective study of 121 patients

Effective compliance (time spent at the effective pressure) with nasal CPAP in obstructive sleep apnea has been reported to be poor. The aim of our study was to evaluate effective compliance in a large European multicenter study. One hundred twenty-one consecutive newly treated patients (initial apnea-hypopnea index [AHI] = 62.0 +/- 29. 5/h, AHI under CPAP = 6.4 +/- 8.1/h, CPAP pressure = 8.7 +/- 2.6 cm H(2)O, BMI = 33.1 +/- 6.8 kg/m(2)) were randomly allocated to a group with (MC(+)) (n = 58) or without (MC(-)) (n = 63) a control unit measuring effective compliance at 1, 2, and 3 mo, which was compared with the built-in time counter data. MC(+) data were 94 +/- 10, 98 +/- 5, and 96 +/- 9% of counter data at 1, 2, and 3 mo, respectively. Using criteria of regular use already reported in the literature (at least 4 h of nCPAP per day of use and nCPAP administered more than 70% of the days) we found 77, 82, and 79% compliant patients at 1, 2, and 3 mo, respectively, 79% of the patients meeting these criteria each month. Although there were no pulmonary functions or polysomnographic differences between the two subgroups, the compliant patients did report a greater improvement in minor symptoms. We found a close correlation between effective use of CPAP and the machine run time. The main result of our study was a higher effective compliance than previously reported, approximately 80% of the patients being regular users versus 46% in a previously published study. This may result from different technical and medical follow-up.

Periodic limb movements and obstructive sleep apneas before and after continuous positive airway pressure treatment

Periodic limb movements during sleep (PLMS) and obstructive sleep apnea syndrome (OSAS) are two common sleep disorders. The similarity in periodicity of periodic limb movements (PLMs) and obstructive sleep apneas (OSAs) led us to hypothesize the existence of a common central generator responsible for the periodicity of both OSAs and PLMs. In order to test this hypothesis, we compared apnea periodicity before continuous positive airway pressure (CPAP) treatment with PLMs periodicity during CPAP treatment in 26 OSA patients, consecutively recorded and treated in our sleep laboratory. The investigation on CPAP was performed twice, once during the initial evaluation and once during a follow-up evaluation after 3 months of home treatment with CPAP. Our results showed that, in this sample, 16 patients out of 26 had an association of OSAS and PLMS, defined as the occurrence of at least 5 PLMs per hour of sleep. The mean apnea interval - measured as the time between the beginning of two successive apneas - was 43.1 s (+/-15.2, SD) and the mean PLM interval - calculated in the same way - was 29.6 s (+/-15.2) during the baseline night, 28.5 s (+/-15.7) during the first CPAP night, and 29.8 s (+/-14.8) during the second CPAP night. Thus, the periodicity of the two phenomena (apneas and PLMs) was different, both before and after CPAP treatment (P< 0.05). When considering the interval between the end of an event (apnea or PLM) and the beginning of the next one the mean apnea interval was 19.5 s (+/-11. 6), and the mean PLM interval was 28.1 s (+/-15.3) during the untreated night, 26.6 s (+/-16) during the first CPAP night and 27.9 s (+/-15) during the second CPAP night. The shortening of apnea intervals with this method of measuring intervals reflects the longer duration of apneas as compared to PLMs. Again the intervals between PLMs were not different between each other but the intervals between apneas were different from the intervals between PLMs (P< 0. 05) These results show that the periodicity of PLMs is different from that of OSAs, suggesting that sleep apneas and PLMs are not generated by a common central generator.

Linking community-based blood pressure measurement to clinical care: a randomized controlled trial of outreach and tracking by community health workers

OBJECTIVES

This study assessed the effectiveness of enhanced tracking and follow-up services provided by community health workers in promoting medical follow-up of persons whose elevated blood pressures were detected during blood pressure measurement at urban community sites.

METHODS

In a randomized controlled trial, 421 participants received either enhanced or usual referrals to care. Participants were 18 years or older, were either Black or White, and had blood pressure greater than or equal to 140/90 mm Hg and income equal to or less than 200% of poverty. The primary outcome measure was completion of a medical follow-up visit within 90 days of referral.

RESULTS

The enhanced intervention increased follow-up by 39.4% (95% confidence interval [CI] = 14%, 71%; P = .001) relative to usual care. Follow-up visits were completed by 65.1% of participants in the intervention group, compared with 46.7% of those in the usual-care group. The number needed to treat was 5 clients (95% CI = 3, 13) per additional follow-up visit realized.

CONCLUSIONS

Enhanced tracking and outreach increased the proportion of persons with elevated blood pressure detected during community measurement who followed up with medical care.

Therapeutic use of auto-CPAP

Auto-CPAP is a new technology by which a continuous positive airway pressure (CPAP) device automatically adjusts the level of mask pressure to the patient's requirements. It has been proposed with two different goals: (1) to improve treatment and (2) to perform automatic titration. The improvement of treatment involves two aspects: (a) improving treatment efficacy and (b) improving compliance with treatment. The rationale behind better treatment efficacy is that the patients' requirements vary over both the short and long term. However, there are few data in the literature showing that this is true, let alone concerning its importance and impact. Published studies fail to demonstrate better treatment efficacy with auto-CPAP compared with manually titrated conventional CPAP. The rationale behind improved compliance with treatment is that auto-CPAP should achieve the same treatment efficacy with lower nasal pressures, and thus reduce side effects and improve compliance. Again, the postulate that higher nasal pressures cause lower compliance is not supported. Published studies show variable results both on the level of pressure delivered with an auto-CPAP device (as compared with the optimal pressure used with conventional fixed pressure, but this probably depends on the definition of optimal fixed pressure) and on observed compliance with auto-CPAP. The main problem here is that most studies were not double-blinded which is critical as the end-point (i.e., patient compliance), heavily depends on the relationship between the medical staff and the patient. The aim of titration with auto-CPAP is to save on costs, as patients are treated with fixed conventional CPAP once the titration procedure is accomplished. Auto-titration can be performed either in the sleep laboratory (then the auto-titrating devices can be sophisticated and cumbersome) or in the patients' home. Published studies suggest that auto-titration can be accurately performed, but given the additional cost of the device, the necessity of supervision (albeit a less qualified supervision than with manual titration) and the failure rate, the cost-effectiveness of auto-titration remains to be established.

Prognostic value of lung function and pulmonary haemodynamics in OSA patients treated with CPAP

The aim of the present study was to determine survival rates of obstructive sleep apnoea patients treated with continuous positive airway pressure (CPAP) and to investigate the prognostic value of pretreatment lung function and pulmonary haemodynamics. Two hundred and ninety-six patients, exhibiting > or = 20 apnoeas plus hypopnoeas per hour of sleep, were included. Patients were treated with nasal CPAP and regularly followed up. The cumulative survival rates were 0.96 (95% confidence interval (CI): 0.94-0.99) at 3 yrs and 0.93 (95% CI: 0.91-0.97) at 5 yrs. Most patients died from cardiovascular disease. Apart from age, covariates associated with a lower survival were the presence of a heavy smoking history, a low vital capacity, a low forced expiratory volume in one second (FEV1) and a high mean pulmonary artery pressure. Only three covariates were included by forward stepwise selection in the multivariate analysis, smoking habit (>30 pack-yrs), age and FEV1. The observed survival rates of the group as a whole were similar to those of the general population matched in terms of age, sex and smoking habit, except for patients between 50 and 60 yrs old who had reduced survival. This difference disappeared when patients of the present study with an associated chronic obstructive pulmonary disease were excluded from the comparison. In conclusion, survival of obstructive sleep apnoea patients treated with nasal continuous positive airway pressure is near to that of the general population. The prognosis is worse in subgroups of patients with a history of heavy smoking and with an associated chronic obstructive pulmonary disease.

Different TBX5 interactions in heart and limb defined by Holt-Oram syndrome mutations

To better understand the role of TBX5, a T-box containing transcription factor in forelimb and heart development, we have studied the clinical features of Holt-Oram syndrome caused by 10 different TBX5 mutations. Defects predicted to create null alleles caused substantial abnormalities both in limb and heart. In contrast, missense mutations produced distinct phenotypes: Gly80Arg caused significant cardiac malformations but only minor skeletal abnormalities; and Arg237Gln and Arg237Trp caused extensive upper limb malformations but less significant cardiac abnormalities. Amino acids altered by missense mutations were located on the three-dimensional structure of a related T-box transcription factor, Xbra, bound to DNA. Residue 80 is highly conserved within T-box sequences that interact with the major groove of target DNA; residue 237 is located in the T-box domain that selectively binds to the minor groove of DNA. These structural data, taken together with the predominant cardiac or skeletal phenotype produced by each missense mutation, suggest that organ-specific gene activation by TBX5 is predicated on biophysical interactions with different target DNA sequences.