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Background: Sleep and arousal disorders are common, but the underlying physiology of wakefulness is not fully understood. The locus coeruleus promotes arousal via alpha-1 adrenergic receptor (α 1 AR) driven recruitment of wake-promoting dopamine (DA) neurons in the ventral periaqueductal gray (vPAG DA neurons). α 1 AR expression is enriched on vPAG astrocytes, and chemogenetic activation of astrocytic G q signaling promotes wakefulness. Astrocytes can release extracellular "gliotransmitters," such as ATP and adenosine, but the mechanism underlying how vPAG astrocytic α 1 ARs influence sleep/wake behavior and vPAG DA neuron physiology is unknown., Methods: In this study, we utilized genetic manipulations with ex vivo calcium imaging in vPAG DA neurons and astrocytes, patch-clamp electrophysiology, and behavioral experiments in mice to probe our hypothesis that astrocytic α 1 ARs mediate noradrenergic modulation of wake-promoting vPAG DA neurons via adenosine signaling., Results: Activation of α 1 ARs with phenylephrine increased calcium transients in vPAG DA neurons and vPAG astrocytes, and increased vPAG DA neuron excitability ex vivo. Chemogenetic Gq-DREADD activation of vPAG astrocytes similarly increased vPAG DA neuron calcium activity and intrinsic excitability. Conversely, shRNA knockdown of vPAG astrocytic α 1 ARs reduced the excitatory effect of phenylephrine on vPAG DA neurons and blunted arousal during the wake phase. Pharmacological blockade of adenosine 2A (A 2A ) receptors precludes the α 1 AR-induced increase in vPAG DA calcium activity and excitability in brain slices, as well as the wake-promoting effects of vPAG α 1 AR activation in vivo., Conclusions: We have identified a crucial role for vPAG astrocytic α 1 AR receptors in sustaining arousal through heightened excitability and activity of vPAG DA neurons mediated by local A 2A receptors., (Copyright © 2024. Published by Elsevier Inc.)

Objective: Management of patients with severe aortic stenosis (AS) may differ according to the patient sex. This study aimed to describe patterns of aortic valve replacement (AVR) for severe AS across Europe, including stratification by sex., Methods: Procedure volume data for surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) for six years (2015-2020) were extracted from national databases for Austria, Czech Republic, Denmark, England, Finland, France, Germany, Norway, Poland, Spain, Sweden, and Switzerland and stratified by sex. Patients per million population (PPM) undergoing AVR per year were calculated using population estimates from Eurostat., Results: Between 2015 and 2019, AVR procedures grew at an average annual rate of 3.9%. In 2020, the average total PPM undergoing AVR across all countries was 339, with 51% of procedures being TAVI and 49% SAVR. AVR PPM varied widely between countries, with the highest and lowest in Germany and Poland, respectively. The average total PPM was higher for men than women (423 vs. 258), but a higher proportion of women (62%) than men (44%) received TAVI. The proportion of TAVI among total AVR procedures increased with age, with an overall average of 96% of men and 98% of women aged ≥85 years receiving TAVI; however, adoption of TAVI varied by country., Conclusions: The analysis of temporal trends in the adoption of TAVI vs. SAVR across Europe showed significant variations. Despite the higher use of TAVI vs. SAVR in women, overall rates of AV intervention in women were lower compared to men., Competing Interests: Declaration of competing interest Nathan Petersen and Jana Kurucova are employees of Edwards Lifesciences, a manufacturer of TAVI and SAVR valves. Peter Bramlage is a research consultant and received funding for performing clinical research into the safe use of aortic valves by Edwards Lifesciences. Sabine Bleiziffer and Tanja Rudolph have held lecture and were part of advisory boards which were held and compensated by Edwards Lifesciences. No specific payment was associated with the development of this manuscript. All authors read and approved the final version of manuscript for publication in international journal of cardiology., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Changes in dynamic cerebral autoregulation (DCA) may contribute to postpartum maternal cerebrovascular complications after preeclampsia. We hypothesized that DCA is impaired in the first week postpartum after diagnosis of preeclampsia with severe features (PSF), compared with normotensive postpartum individuals and healthy non-pregnant female volunteers., Methods: We measured DCA within seven days after delivery in individuals with and without PSF, using transcranial Doppler and continuous arterial blood pressure monitoring with finger plethysmography. Historical data from 28 healthy female non-pregnant volunteers, collected using the same methods, were used for comparison. We used generalized harmonic wavelets to estimate autoregulation parameters (phase shift and gain) in very low frequency and low frequency bands, with lower phase shift and higher gain indicating impaired DCA function. We compared DCA parameters between the three groups using the Kruskal Wallis test., Results: A total of 69 postpartum participants contributed data, of whom 49 had preeclampsia with severe features. Median phase shifts in both postpartum groups were higher compared with historical controls across all frequency ranges (p = 0.001), indicating faster autoregulatory response. Gain was higher in both postpartum groups than in historical controls across all frequency ranges (p = 0.04), indicating impaired dampening effect., Conclusion: We found that postpartum individuals, regardless of preeclampsia diagnosis, had higher phase shifts and higher gain than healthy non-pregnant/postpartum female volunteers. Our results suggest hyperdynamic DCA with impaired dampening effect in the first week postpartum, regardless of preeclampsia diagnosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.)

Background: Andexanet alfa (AA), a factor Xa-inhibitor (FXi) reversal agent, is given as a bolus followed by a 2-hour infusion. This long administration time can delay EVD placement in intracerebral hemorrhage (ICH) patients. We sought to evaluate the safety of EVD placement immediately post-AA bolus compared to post-AA infusion., Methods: We conducted a retrospective study that included adult patients admitted with FXi-associated ICH who received AA and underwent EVD placement The primary outcome was the occurrence of a new hemorrhage (tract, extra-axial, or intraventricular hemorrhage). Secondary outcomes included mortality, intensive care unit and hospital length of stay, and discharge modified Rankin Score. The primary safety outcome was documented thrombotic events., Results: Twelve patients with FXi related ICH were included (EVD placement post-AA bolus, N = 8; EVD placement post-AA infusion, N = 4). Each arm included one patient with bilateral EVD placed. There was no difference in the incidence of new hemorrhages, with one post-AA bolus patient had small, focal, nonoperative extra-axial hemorrhage. Morbidity and mortality were higher in post-AA infusion patients (mRS, post-AA bolus, 4 [4-6] vs. post-AA infusion 6 [5,6], p = 0.24 and post-AA bolus, 3 (37.5 %) vs. post-AA infusion, 3 (75 %), p = 0.54, respectively). One patient in the post-AA bolus group had thrombotic event. There was no difference in hospital LOS (post-AA bolus, 19 days [12-26] vs. post-AA infusion, 14 days [9-22], p = 0.55) and ICU LOS (post-AA bolus, 10 days [6-13] vs. post-AA infusion, 11 days [5-21], p = 0.86)., Conclusion: We report no differences in the incidence of tract hemorrhage, extra-axial hemorrhage, or intraventricular hemorrhage post-AA bolus versus post-AA infusion. Larger prospective studies to validate these results are warranted., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background and Purpose: As "time is brain" in acute stroke triage, the need for automated prognostication tools continues to increase, particularly in rapidly expanding tele-stroke settings. We aimed to create an automated prognostication tool for anterior circulation large vessel occlusion (LVO) stroke based on admission CTA radiomics., Methods: We automatically extracted 1116 radiomics features from the anterior circulation territory on admission CTAs of 829 acute LVO stroke patients who underwent mechanical thrombectomy in two academic centers. We trained, optimized, validated, and compared different machine-learning models to predict favorable outcome (modified Rankin Scale ≤ 2) at discharge and 3-month follow-up using four different input sets: "Radiomics", "Radiomics + Treatment" (radiomics, post-thrombectomy reperfusion grade, and intravenous thrombolysis), "Clinical + Treatment" (baseline clinical variables and treatment), and "Combined" (radiomics, treatment, and baseline clinical variables)., Results: For discharge outcome prediction, models were optimized/trained on n = 494 and tested on an independent cohort of n = 100 patients from Yale. Receiver operating characteristic analysis of the independent cohort showed no significant difference between best-performing Combined input models (area under the curve, AUC = 0.77) versus Radiomics + Treatment (AUC = 0.78, p = 0.78), Radiomics (AUC = 0.78, p = 0.55), or Clinical + Treatment (AUC = 0.77, p = 0.87) models. For 3-month outcome prediction, models were optimized/trained on n = 373 and tested on an independent cohort from Yale (n = 72), and an external cohort from Geisinger Medical Center (n = 232). In the independent cohort, there was no significant difference between Combined input models (AUC = 0.76) versus Radiomics + Treatment (AUC = 0.72, p = 0.39), Radiomics (AUC = 0.72, p = 0.39), or Clinical + Treatment (AUC = 76, p = 0.90) models; however, in the external cohort, the Combined model (AUC = 0.74) outperformed Radiomics + Treatment (AUC = 0.66, p < 0.001) and Radiomics (AUC = 0.68, p = 0.005) models for 3-month prediction., Conclusion: Machine-learning signatures of admission CTA radiomics can provide prognostic information in acute LVO stroke candidates for mechanical thrombectomy. Such objective and time-sensitive risk stratification can guide treatment decisions and facilitate tele-stroke assessment of patients. Particularly in the absence of reliable clinical information at the time of admission, models solely using radiomics features can provide a useful prognostication tool., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Spaceflight and exposure to microgravity have wide-ranging effects on many systems of the human body. At the European Space Agency (ESA), a physiotherapist plays a key role in the multidisciplinary ESA team responsible for astronaut health, with a focus on the neuro-musculoskeletal system. In conjunction with a sports scientist, the physiotherapist prepares the astronaut for spaceflight, monitors their exercise performance whilst on the International Space Station (ISS), and reconditions the astronaut when they return to Earth. This clinical commentary outlines the physiotherapy programme, which was developed over nine long-duration missions. Principles of physiotherapy assessment, clinical reasoning, treatment programme design (tailored to the individual) and progression of the programme are outlined. Implications for rehabilitation of terrestrial populations are discussed. Evaluation of the reconditioning programme has begun and challenges anticipated after longer missions, e.g. to Mars, are considered., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Postflight reconditioning of astronauts is understudied. Despite a rigorous, daily inflight exercise countermeasures programme during six months in microgravity (μG) on-board the International Space Station (ISS), physiological impairments occur and postflight reconditioning is still required on return to Earth. Such postflight programmes are implemented by space agency reconditioning specialists. Case Description and Assessments: A 38 year old male European Space Agency (ESA) crewmember's pre- and postflight (at six and 21 days after landing) physical performance from a six-month mission to ISS are described., Assessments: muscle strength (squat and bench press 1 Repetition Maximum) and power (vertical jump), core muscle endurance and hip flexibility (Sit and Reach, Thomas Test)., Interventions: In-flight, the astronaut undertook a rigorous daily (2-h) exercise programme. The 21 day postflight reconditioning exercise concept focused on motor control and functional training, and was delivered in close co-ordination by the ESA physiotherapist and exercise specialist to provide the crewmember with comprehensive reconditioning support., Outcomes: Despite an intensive inflight exercise programme for this highly motivated crewmember, postflight performance showed impairments at R+6 for most parameters, all of which recovered by R+21 except muscular power (jump tests)., Conclusions: Regardless of intense inflight exercise countermeasures and excellent compliance to postflight reconditioning, postflight performance showed impairments at R+6 for most parameters. Complex powerful performance tasks took longer to return to preflight values. Research is needed to develop optimal inflight and postflight exercise programmes to overcome the negative effects of microgravity and return the astronaut to preflight status as rapidly as possible., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: To determine whether individual differences in emotional reactivity predicted high levels of conduct problems and/or emotional (depressive and anxiety) symptoms at 1-year follow-up in a community sample of 7- to 11-year-old children (N = 659)., Method: The study used a prospective design with picture perception methodology at baseline to elicit emotional responses from children. Conduct problems and symptoms of anxiety and depression were evaluated using repeated measures from self-, teacher, and parent report questionnaires completed at baseline and 1 year., Results: Children who reported decreased emotional arousal to unpleasant (B = -0.069; p = .011) and pleasant (B = -0.134; p = .036) pictures showed higher levels of self-reported and teacher-reported conduct problems at 1-year follow-up, respectively. Conversely, children who reported increased emotional arousal to neutral pictures (B = 0.661; p = .030) at baseline showed higher levels of anxiety symptoms at follow-up. These findings held when baseline level of problems and symptoms, sex, age, socioeconomic status, and IQ were taken into account. Findings were nonsignificant for symptoms of depression at the multivariate level of analyses., Conclusions: Although findings showed that symptom level at baseline remains the best predictor of symptom level at follow-up, these prospective findings extend previous reports in children and adults and provide predictive validity for decreased arousal correlating with high levels of subsequent conduct problems and increased arousal correlating with high levels of subsequent anxiety symptoms. Differences in emotional processing may constitute a risk process for the subsequent onset of conduct and anxiety disorder in middle childhood.

Study Objectives: Proinflammatory cytokines may contribute to disease progression in heart failure by virtue of the direct toxic effects that these molecules exert on the heart and the circulation. Accordingly, there is interest in developing therapeutic agents with anticytokine properties that might be used as adjunctive therapy to modulate proinflammatory cytokine levels in patients with heart failure. Previous experimental studies suggested that vesnarinone has potent anticytokine properties in vitro. Therefore, we examined the effects of vesnarinone on circulating levels of cytokines and cytokine receptors in a large-scale, multicenter, clinical trial of patients with moderate-to-advanced heart failure: the Vesnarinone Trial (VEST)., Methods: Circulating levels of tumor necrosis factor (TNF)-alpha, soluble TNF-receptor type 1, soluble TNF-receptor type 2, as well as interleukin (IL)-6 and soluble IL-6 receptor (sIL-6R) were measured on plasma samples by enzyme-linked immunosorbent assay at baseline and at 24 weeks in patients who were receiving placebo (n = 352), 30 mg of vesnarinone (n = 367), and 60 mg of vesnarinone (n = 327)., Results: Treatment with 30 mg and 60 mg of vesnarinone had no effect on circulating levels of cytokines or cytokine receptors in patients with advanced heart failure over a 24-week period., Conclusions: In contrast to the potent anticytokine effects observed with vesnarinone in experimental studies in vitro, the results of this clinical study suggest that vesnarinone does not have any measurable anticytokine effects in vivo in patients with moderate-to-advanced heart failure.

The authors examined the relationship between functional status and comorbid anxiety and depression and the relationship between utilization of health care resources and psychopathology in elderly patients with chronic obstructive pulmonary disease (COPD). Elderly male veterans (N = 43) with COPD completed anxiety, depression, and functional status measures. The authors constructed regression models to explore the contribution of COPD severity, medical burden, depression, and anxiety to the dependent variables of functional impairment and health care utilization. Anxiety and depression contributed significantly to the overall variance in functional status of COPD patients, over and above medical burden and COPD severity, as measured by the 8 scales of the Medical Outcomes Study (MOS) 36-item Short Form Health Survey. Surprisingly, medical burden and COPD severity did not contribute significantly to overall variance in functional status. Few patients were receiving any treatment for anxiety or depression.

Objectives: To measure the effect of baclofen on the transmission in different spinal pathways to soleus motoneurones in spastic multiple sclerosis patients., Methods: Baclofen was administered orally in 14 and intrathecally in 8 patients. H(max)/M(max), presynaptic inhibition by biceps femoris tendon tap of femoral nerve stimulation, depression of the soleus H-reflex following previous activation of the Ia afferents from the soleus muscle (i.e. postactivation depression), disynaptic reciprocal Ia inhibition of the soleus H-reflex and the number of backpropagating action potentials in primary afferents, which may be a sign of presynaptic inhibition, were examined., Results: Baclofen depressed the soleus H(max)/M(max) ratio significantly following oral and intrathecal baclofen. None of the two tests of presynaptic inhibition, or the postactivation depression or the disynaptic reciprocal Ia inhibition of the soleus H-reflex were affected by baclofen administration. Also the action potentials of the primary afferents were unchanged during baclofen administration., Conclusions: The antispastic effect of baclofen is not caused by an effect on the transmitter release from Ia afferents or on disynaptic reciprocal Ia inhibition. One possible explanation of the depression of the H-reflex by baclofen is suggested to be a direct depression of motoneuronal excitability.

To investigate factors related to lung cancer mortality in six Arizona copper smelter towns, we identified 185 lung cancer cases and two matched controls per case from decedent residents during 1979-1990. Detailed information on lifetime residential, occupational, and smoking history was obtained by structured telephone interviews with knowledgeable informants. Interviews were completed for 82% of 183 eligible cases and 88% of the targeted number (366) of controls. Estimated historical environmental exposures to smelter emissions, based on atmospheric diffusion modeling of measured SO2 concentrations, were linked with residential histories to derive individual profiles of residential exposure. Occupational histories were characterized by potential exposure to smelter emissions, asbestos, and ionizing radiation. Conditional logistic regression was used to compare study factors in cases and controls with adjustment for potential confounding factors: gender, Hispanic ethnicity, and smoking. In overall and gender-specific analyses, no statistically significant associations were observed between lung cancer risk and any of the measures of residential exposure to smelter emissions considered (town of residence at time of death, highest level of exposure, and duration or cumulative exposure above background levels), or any of the estimated occupational exposures (definite or potential asbestos, potential ionizing radiation, definite or potential smelter). Among male residents of some, but not all, towns, there was some evidence of a positive association between lung cancer risk and reported copper smelter-related employment (reported as definite), with the highest risk observed for Miami, Arizona. This study provided little evidence of a positive association between lung cancer mortality and residential exposure to smelter emissions. Specific factors associated with the apparent heterogeneity in lung cancer risk across study towns cannot be identified in this community-based study.

The objectives of this study were to determine the ability of trophectoderm from preimplantation ovine embryos to synthesize hsp70 in response to heat shock and to identify conditions which induce translational thermotolerance in this tissue. Day 15 embryos were collected, and proteins synthesized in 1.5-mm sections of trophectoderm were radioactively labeled with (35)S-methionine. One-dimensional SDS-PAGE gels, two-dimensional gel electrophoresis and Western blots were utilized to characterize the heat shock response and to examine the induction of translational thermotolerance. Increased synthesis of the 70 kDa heat shock proteins and a protein with an approximate molecular weight of 15 to 20 kDa was observed with heat shock (> or = 42 degrees C). Total protein synthesis decreased (P < 0.05) with increased intensity of heat shock. At 45 degrees C, protein synthesis was suppressed with little or no synthesis of all proteins including hsp70. Recovery of protein synthesis following a severe heat shock (45 degrees C for 20 min) occurred faster (P < 0.05) in trophectoderm pretreated with a mild heat shock (42 degrees C for 30 min) than trophectoderm not pretreated with mild heat. In summary, trophoblastic tissue obtained from ovine embryos exhibit the characteristic "heatshock" response similar to that described for other mammalian systems. In addition, a sublethal heat shock induced the ability of the tissue to resume protein synthesis following severe heat stress. Since maintaining protein synthesis is crucial to embryonic survival, manipulation of the heat-shock response may provide a method to enhance embryonic survival.

Using a simple, standardized denaturing gradient gel electrophoresis (DGGE) based mutation screening technique, a novel G-to-A mutation in the last base of the intron 12 splice acceptor site of the LDL receptor gene was found in 2 Danish families with familial hypercholesterolemia (FH). The mutation is shown to result in 2 mRNA splice variants, both leading to truncated LDLR proteins, containing only the first 594 of the normal 839 amino acids. In one of the FH-families harbouring the mutation, a striking difference in the clinical picture amongst biochemically diagnosed FH patients was clarified when genetic analysis showed that 2 hypercholesterolemic family members, who despite advanced age had no atherosclerotic disease, had not inherited the family LDLR mutation. DGGE analyses of the LDLR exons, LDLR promoter, and apolipoprotein B codon 3456-3553 as well as Southern blotting of the LDLR gene were without signs of other mutations in the non-atherosclerotic hypercholesterolemics of the family. Availability of the clinically applicable mutation screening assay for FH may thus aid in defining reasons for phenotypic differences in FH families and potentially supply information allowing a more differentiated therapeutic approach to individual members of FH families.

We performed a screening of exon 9 of the low density lipoprotein receptor (LDLR) gene in 14 Danish families with familial hypercholesterolemia (FH) using the denaturing gradient gel electrophoresis (DGGE) technique. In one of the probands from these families an abnormal band pattern in the gradient gel was detected. Subsequent DGGE analysis of the family of this index patient revealed that the DGGE pattern cosegregated with the disease in this family. Sequencing of the exon showed a deletion of a C in codon 424 of the LDLR gene resulting in a frame shift with the introduction of a stop codon 5 codons further downstream. The mutation is referred to as FH-Odense. The predicted truncated receptor protein consists of the 428 amino terminal amino acids. Consequently, the cytosolic and membrane spanning parts of the mature LDL receptor, which normally secure the receptor in the plasma membrane, are missing. The FH-Odense mutation results in severe premature coronary atherosclerosis as shown by the clinical expression in 5 generations of the affected family.

We describe in this paper details of morphogenesis of wing hairs in Drosophila pupae. The ultimate objective is to relate specific protein components used in hair construction to specific components produced in the rapidly changing patterns of gene expression that are characteristic for the period of hair differentiation in wing cells (H. K. Mitchell and N. S. Petersen, 1981, Dev. Biol. 85, 233-242). Hair extrusion to essentially full size occurs quite suddenly at about 34 hr (postpupariation) and this is followed by deposition of a double-layer of cuticulin during the next 4 to 5 hr. Extreme changes in shape of cells and hairs, probably related to actin synthesis, then occur for the next 5 to 6 hr. Deposition of fibers within the hairs and on hair pedestals follows. Formation of cuticle on the cell surface begins and continues until some time in the 60-hr range. It appears that cuticle is formed only on the cell surface and not in hairs or on the top of hair pedestals. The protein synthesis patterns associated with these events are described.

Phenocopies are developmental defects induced by environmental treatments during differentiation. Because of their resemblance to mutant phenotypes it has been suggested that phenocopies are due to environmental effects on the expression of specific genes during development. In this paper we describe the heat shock (40.8 degrees C) induction of a multiple wing hair phenocopy in the mutant heterozygote (mwh/+). The mwh phenocopy is only induced in heterozygotes of the recessive mutant during a short sensitive period which appears to be the time of expression of the multiple wing hair gene. We suggest that this phenocopy is due to failure of mwh gene expression and that phenocopy sensitive periods may be useful in identifying expression periods for particular genes during development. Furthermore we have been able to demonstrate that a 35 degrees C pretreatment will prevent the induction of the multiple wing hair phenocopy. A similar 35 degrees C pretreatment prevents induction of several different phenocopies by heat in wild-type flies (N. S. Petersen and H. K. Mitchell (1985). In "Comprehensive Insect Physiology, Biochemistry and Pharmacology, Vol. X, Biochemistry." Pergamon, New York). This indicates a common molecular mechanism for both the induction and the prevention of heat-induced phenocopies.

We present evidence to show that differentiation in wing cells to produce hairs is synchronous over the distal 90% of the wing surface (approximately 28,000 cells). In spite of this synchrony within such a large area a temporal gradient exists between zones (in general anterior to posterior) on the animal surface with rather sharp boundaries in between. In order to evaluate the basis for the gradient we studied two mutants which carry different combinations of the genes of the bithorax complex. These were examined with respect to the temporal aspects of sensitivity to heat shock induction of the multihair phenocopy on wings and the time of initiation of the program of protein synthesis that is related to hair formation. Results show that the gradient observed is based on predetermined properties within specific areas of tissue rather than on the position of the cells in the animal.

Between July 24 and Aug. 19, 1974, an outbreak of pyrogenic reactions occurred in patients at a private haemodialysis centre in a suburb of Washington, D.C. 49 reactions characterised by chills, fever, and hypotension occurred in twenty-three of the seventy patients dialysed during this period. No infections could be documented in any of the affected individuals. Despite the fact that only low levels of gram-negative bacterial contamination of the haemodialysis system were found, high levels of endotoxin contamination of dialysis fluid and endotoxaemia in patients experiencing overt reactions were recorded using the Limulus lysate test. The cause of these reactions was traced to an increase in endotoxin contamination of the tap water used to prepare dialysate, possibly caused by an increase in the algae levels in the local water source. The installation of a reverse osmosis system for water treatment may be a solution to the problem of endotoxin contamination of water used to prepare dialysis fluid.

Forty samples of air with a mean sample volume of 104 liters were collected during the treatment of patients whose blood was positive for HBsAG: no samples contained HBsAG and occult blood. These findings suggest that, if environmentally mediated transmission of hepatitis B occurs in the dental operatory, it is more likely to occur through contact with contaminated surfaces than through the airborne route.