A two-year, double-blind comparison of estrogen-androgen and conjugated estrogens in surgically menopausal women. Effects on bone mineral density, symptoms and lipid profiles

OBJECTIVE

To compare the effects of two doses of conjugated equine estrogen (CEE) and two of esterified estrogen plus methyltestosterone (E + A) in surgically menopausal women.

STUDY DESIGN

A two-year, parallel-group, double-blind study of 311 women who were randomly assigned to one of four regimens: (1) CEE, 0.625 mg/d; (2) CEE, 1.25 mg/d; (3) esterified estrogens, 0.625 mg, + methyltestosterone, 1.25 mg/d; or (4) esterified estrogens, 1.25, + methyltestosterone, 2.5 mg/d. Study parameters were symptoms, lipids, bone mineral density, side effects and safety.

RESULTS

All treatments prevented loss of bone in the spine and hip. The higher E + A dose increased spine and hip BMD more than other treatments (P < .002). All treatments improved menopausal symptoms, with non-significantly greater improvements in well-being and sexual interest in the E + A groups. Similar and significant decreases in low-density lipoprotein were observed in all groups, but high-density lipoprotein and triglycerides were increased only in the unopposed estrogen groups (P < .05). Hirsutism was uncommon and similar in all groups at two years. Discontinuation rates and reasons for withdrawal from the study were similar in both groups. No clinically significant side effects or laboratory test abnormalities were seen.

CONCLUSION

As compared to estrogen alone, E + A significantly improved BMD and was well tolerated in surgically menopausal women.

The Canadian Study of Cardiac Transplantation. Atherosclerosis. Investigators of the CASCADE Study

OBJECTIVES

To describe risk factors associated with the development of transplantation coronary artery disease (TCAD).

DESIGN

A retrospective study of the Canadian experience.

PATIENTS

Seven hundred and nineteen patients with follow-up of at least 12 months following transplantation and a minimum of one coronary angiogram were analyzed.

RESULTS

Two hundred and fourteen patients (30%) developed angiographic evidence of TCAD during an average follow-up of 50+/-25 months. Actuarial freedom rate from TCAD averaged 60%, and survival averaged 85% five years following transplantation. Abnormal coronary angiograms increased from 11% to 40% between the first and the fifth year following transplantation. The Cox multivariate final model showed that recipients of donor hearts of 50 years and older (RR 4.35, 95% CI 2.32 to 8.15), patients with two or more episodes of acute rejection (RR 1.56, 95% CI 1.11 to 2.21) and patients with a diagnosis of ischemic cardiomyopathy before transplantation (RR 1.38, 95% CI 1.03 to 1.84) were at higher risk of TCAD. The same risk factors also had a significant effect on survival, although patients who were administered a hepatic hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor during follow-up had a higher survival rate (95% versus 85%, P=0.01) five years following heart transplantation.

CONCLUSIONS

Recipients of hearts from older donors, patients with an ischemic heart disease before transplantation and those with several episodes of acute rejection are at increased risk for TCAD. Patients who are administered an HMG-CoA reductase inhibitor during follow-up have a higher survival rate five years following transplantation.

A polymorphism in the regulatory region of the CC-chemokine receptor 5 gene influences perinatal transmission of human immunodeficiency virus type 1 to African-American infants

There are natural mutations in the coding and noncoding regions of the human immunodeficiency virus type 1 (HIV-1) CC-chemokine coreceptor 5 (CCR5) and in the related CCR2 protein (the CCR2-64I mutation). Individuals homozygous for the CCR5-Delta32 allele, which prevents CCR5 expression, strongly resist HIV-1 infection. Several genetic polymorphisms have been identified within the CCR5 5' regulatory region, some of which influence the rate of disease progression in adult AIDS study cohorts. We genotyped 1,442 infants (1,235 uninfected and 207 HIV-1 infected) for five CCR5 and CCR2 polymorphisms: CCR5-59353-T/C, CCR5-59356-C/T CCR5-59402-A/G, CCR5-Delta32, and CCR2-64I. The clinical significance of each genotype was assessed by measuring whether it influenced the rate of perinatal HIV-1 transmission among 667 AZT-untreated mother-infant pairs (554 uninfected and 113 HIV-1 infected). We found that the mutant CCR5-59356-T allele is relatively common in African-Americans (20.6% allele frequency among 552 infants) and rare in Caucasians and Hispanics (3.4 and 5.6% of 174 and 458 infants, respectively; P < 0.001). There were 38 infants homozygous for CCR5-59356-T, of whom 35 were African-Americans. Among the African-American infants in the AZT-untreated group, there was a highly significant increase in HIV-1 transmission to infants with two mutant CCR5-59356-T alleles (47.6% of 21), compared to those with no or one mutant allele (13.4 to 14.1% of 187 and 71, respectively; P < 0.001). The increased relative risk was 5.9 (95% confidence interval, 2.3 to 15.3; P < 0.001). The frequency of the CCR5-59356-T mutation varies between population groups in the United States, a low frequency occurring in Caucasians and a higher frequency occurring in African-Americans. Homozygosity for CCR5-59356-T is strongly associated with an increased rate of perinatal HIV-1 transmission.

Identification of a new recipient in the Sydney Blood Bank Cohort: a long-term HIV type 1-infected seroindeterminate individual

We have reported previously a cohort of long-term survivors of HIV-1 infection, known as the Sydney Blood Bank Cohort, who received HIV-1-positive blood from a common infected donor. A new recipient, C135, has been identified. This recipient became infected after receiving blood donated during the presumed time of seroconversion of the donor in February 1981. C135 has been infected for more than 18 years without signs of disease progression. The virus load in this recipient has remained below the detectable level (<20 RNA copies/ml of plasma) and repeated Western blot analyses have given an indeterminate result. By booster PCR techniques we have demonstrated that this individual is infected with HIV-1 and have characterized the viral nef and nef/LTR region sequences present. The strain of HIV-1 identified contains deletions of 88 bp from the nef alone region and a total of 139 bp deleted from the nef/LTR overlap and LTR regions. The LTR contains three wild-type Sp1 transcription factor-binding sites, the 3' wildtype NF-kappaB site, and a duplicated Sp1 and NF-kappaB region. A truncated Nef protein of only 19 amino acids is encoded. The deletions and rearrangements in the nef gene and LTR sequences are characteristic of Sydney Blood Bank Cohort strains of virus. The identification of C135 increases the Sydney Blood Bank Cohort size to nine individuals and represents a rare example of a genuine, long-term HIV-1 infection accompanied by indeterminate anti-HIV-1 serology.

The overactive bladder: neuropharmacological basis of clinical management

The overactive bladder continues to pose a major challenge to clinicians treating lower urinary tract disorders, not least because our understanding of the pathogenesis of detrusor overactivity is still relatively limited. However, progress in understanding the basis of the overactive bladder is moving steadily forward, accompanied by a growing number of different forms of treatment. New pharmacological treatments and variations in the mode of delivery of older agents offer hope of efficacy with fewer side-effects. Neuromodulation is also offering a viable alternative to surgery in patients unresponsive to medical treatment.

Rapid radiation events in the family Ursidae indicated by likelihood phylogenetic estimation from multiple fragments of mtDNA

The bear family (Ursidae) presents a number of phylogenetic ambiguities as the evolutionary relationships of the six youngest members (ursine bears) are largely unresolved. Recent mitochondrial DNA analyses have produced conflicting results with respect to the phylogeny of ursine bears. In an attempt to resolve these issues, we obtained 1916 nucleotides of mitochondrial DNA sequence data from six gene segments for all eight bear species and conducted maximum likelihood and maximum parsimony analyses on all fragments separately and combined. All six single-region gene trees gave different phylogenetic estimates; however, only for control region data was this significantly incongruent with the results from the combined data. The optimal phylogeny for the combined data set suggests that the giant panda is most basal followed by the spectacled bear. The sloth bear is the basal ursine bear, and there is weak support for a sister taxon relationship of the American and Asiatic black bears. The sun bear is sister taxon to the youngest clade containing brown bears and polar bears. Statistical analyses of alternate hypotheses revealed a lack of strong support for many of the relationships. We suggest that the difficulties surrounding the resolution of the evolutionary relationships of the Ursidae are linked to the existence of sequential rapid radiation events in bear evolution. Thus, unresolved branching orders during these time periods may represent an accurate representation of the evolutionary history of bear species.

In rats, odor-induced Fos in the olfactory pathways depends on the phase of the circadian clock

We used immunostaining for Fos to study the effect of circadian clock phase on odor-induced neuronal activation in the olfactory system in rats. Brief presentation of cedar odor to rats housed in constant darkness stimulated Fos expression in the main olfactory bulb, anterior olfactory nucleus, piriform cortex, and several other odor-responsive structures, both in the subjective day and subjective night phases of the cycle. Fos expression in response to odor, but not basal expression, was greatly enhanced in the subjective night in all structures examined. These findings are consistent with the idea that odor-induced neuronal activation in the olfactory pathways is modulated by the phase of the circadian clock.

Evaluation of consumer drug information databases

OBJECTIVES

To evaluate prescription drug information contained in six consumer drug information databases available on CD-ROM, and to make health care professionals aware of the information provided, so that they may appropriately recommend these databases for use by their patients.

DESIGN

Observational study of six consumer drug information databases: The Corner Drug Store, Home Medical Advisor, Mayo Clinic Family Pharmacist, Medical Drug Reference, Mosby's Medical Encyclopedia, and PharmAssist.

SETTING

Not applicable.

PATIENTS OR OTHER PARTICIPANTS

Not applicable.

INTERVENTIONS

Information on 20 frequently prescribed drugs was evaluated in each database. The databases were ranked using a point-scale system based on primary and secondary assessment criteria.

MAIN OUTCOME MEASURES

For the primary assessment, 20 categories of information based on those included in the 1998 edition of the USP DI Volume II, Advice for the Patient: Drug Information in Lay Language were evaluated for each of the 20 drugs, and each database could earn up to 400 points (for example, 1 point was awarded if the database mentioned a drug's mechanism of action). For the secondary assessment, the inclusion of 8 additional features that could enhance the utility of the databases was evaluated (for example, 1 point was awarded if the database contained a picture of the drug), and each database could earn up to 8 points.

RESULTS

The results of the primary and secondary assessments, listed in order of highest to lowest number of points earned, are as follows: Primary assessment--Mayo Clinic Family Pharmacist (379), Medical Drug Reference (251), PharmAssist (176), Home Medical Advisor (113.5), The Corner Drug Store (98), and Mosby's Medical Encyclopedia (18.5); secondary assessment--The Mayo Clinic Family Pharmacist (8), The Corner Drug Store (5), Mosby's Medical Encyclopedia (5), Home Medical Advisor (4), Medical Drug Reference (4), and PharmAssist (3).

CONCLUSION

The Mayo Clinic Family Pharmacist was the most accurate and complete source of prescription drug information based on the USP DI Volume II and would be an appropriate database for health care professionals to recommend to patients.

Cytokine production in rhesus monkeys infected with Plasmodium coatneyi

Plasmodium coatneyi infection in rhesus monkeys has been used as a model for studying human malaria. Cytokine production in this model, however, has so far not been examined. In this study, four rhesus monkeys were infected with P. coatneyi, with another four animals serving as uninfected controls. Blood samples were taken for the determination of daily parasitemia, and cytokine and prostaglandin E2 (PGE2) levels at days 0, 3, 5, 7, and 10. All inoculated animals became infected, with synchronized appearance of ring-stage parasites. Infected monkeys had increased plasma levels of proinflammatory cytokines (interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha) during the late stage of the infection. They also had increased production of ciliary neurotrophic factor. In conjunction with the production of proinflammatory cytokines, infected monkeys also had gradual increases in the production of PGE2. A continued definition of the P. coatneyi/rhesus monkey animal model should be useful for the elucidation of the immunopathogenesis of human malaria.

Vitamin A deficiency phrynoderma: due to malabsorption and inadequate diet

We describe a patient with vitamin A deficiency phrynoderma caused by a combination of inadequate dietary intake of vitamin A and beta-carotene and malabsorption secondary to primary visceral myopathy and total colectomy.

Spinal cord injury research: review and synthesis

This article provides a substantive review and synthesis of major areas of emphasis in spinal cord injury (SCI) research. Comprehensive examination of the current status and future implications for SCI research includes consideration of investigations from the following arenas: epidemiology, functional classification and prediction, neurophysiologic testing, models of injury and recovery, psychosocial considerations, surgical strategies, animal laboratory research, economic implications, life expectancy, complication rates, gender differences, pharmacological management, and prevention. Synthesis of these research conclusions from a broad spectrum of laboratory, clinical, and scientific domains provides opportunity for improving SCI prevention, treatment, and adaptation.

Olfactory stimulation enhances light-induced phase shifts in free-running activity rhythms and Fos expression in the suprachiasmatic nucleus

There is evidence to suggest that the olfactory and circadian systems are linked, functionally, and that olfactory stimuli can modulate circadian rhythms in mammals. Furthermore, olfactory bulb removal can alter free-running rhythms in animals housed in constant darkness and can attenuate the effect of social stimuli on photic entrainment of circadian rhythms. The mechanisms through which olfactory stimuli influence circadian rhythms are not known. One possibility is that olfactory stimuli influence circadian rhythms by modulating the activity of the circadian clock located in the hypothalamic suprachiasmatic nucleus. To study this, we assessed the effect of olfactory stimulation on free-running rhythms and on photic resetting of the circadian clock in rats using phase shifts in wheel-running rhythms and expression of the transcription factor Fos in the suprachiasmatic nucleus. We found that brief exposure to an olfactory stimulus, cedar wood essence, in the subjective day or subjective night had no effect on either free-running rhythms or Fos expression in the suprachiasmatic nucleus, but that when presented in combination with light, the odor dramatically enhanced light-induced phase shifts and Fos expression in the suprachiasmatic nucleus. Olfactory stimulation alone induced Fos expression in several structures that innervate the suprachiasmatic nucleus, pointing to ways by which stimulus information transmitted in the olfactory pathways could gain access to the suprachiasmatic nucleus to modulate photic resetting. These findings, showing that clock resetting by light can be facilitated by olfactory stimulation, point to a mechanism by which olfactory cues can modulate entrainment of circadian rhythms.

Pharmacological management of incontinence

Many patients with incontinence do not need surgery - for these patients symptoms can often be considerably improved by conservative measures, including drugs. Several different pharmacological actions are potentially useful depending on the underlying cause of the incontinence: a) Detrusor instability (DI) responds to drugs reducing bladder contractility: Anticholinergic agents, e.g. oxybutynin and tolterodine, act at postganglionic parasympathetic cholinergic receptor sites on the detrusor muscle, reducing the strength of the detrusor contraction. Tricyclic antidepressants, e.g. imipramine, have anticholinergic effects, block presynaptic uptake of amine neurotransmitters and directly inhibit detrusor muscle. Alpha-adrenergic antagonists may have a role to play by dual actions on bladder overactivity (due to altered receptor function) and by reducing outlet resistance. b) Genuine stress incontinence (GSI) may be treated using alpha-adrenergic agonists, e.g. phenylpropanolamine, to increase outlet resistance by stimulating smooth muscle of the urethra and bladder neck. c) In nocturnal enuresis reduction of nocturnal urine output with the anti-diuretic hormone (ADH) analogue DDAVP (1-deamino, 8-arginine vasopressin) is beneficial. d) Bladder emptying may be facilitated in patients with retention and 'overflow' incontinence by alpha-adrenergic antagonists, which reduce outlet resistance, and perhaps by parasympathomimetics, e.g. bethanecol. e) In postmenopausal women, systemic oestrogen replacement reduces filling symptoms including urge incontinence. Evidence for oestrogen replacement alone in GSI is lacking, but combination with alpha-agonists is beneficial in milder GSI. For the future, tolterodine and other new anticholinergics offer the hope of treatment for DI with fewer of the side effects that limit the use of established drugs. Better understanding of the pathophysiology of DI may provide new targets for drug therapy, such as hyperpolarisation of detrusor muscle membrane. Alpha-agonists may find a greater role in the future, as may ADH analogues for noctural symptoms.

Overactive detrusor

Detrusor overactivity poses a major challenge to physicians from many specialities. Progress in our understanding of the pathogenesis of detrusor overactivity is slow but steady. Advances in treatment continue to be made, both with new agents and new methods of delivering older drugs. Neuromodulation is showing great promise as experience increases, and developments in bladder augmentation offer hope for lower morbidity treatments in future.

Treatment of a coronary artery to superior vena cava fistula resulting from early closure of a Possis Perma-Flow graft

The Perma-Flow graft used in bypass surgery achieves more complete revascularization when paucity of native conduits exists. We report a coronary artery to superior vena cava fistula as a complication of this graft, leading to severe right heart failure. The fistula was successfully occluded percutaneously, improving the patient's clinical situation.

Definition of the stage of host cell genetic restriction of replication of human immunodeficiency virus type 1 in monocytes and monocyte-derived macrophages by using twins

Using identical (ID) twins, we have previously demonstrated that host cell genes exert a significant impact on productive human immunodeficiency virus (HIV) infection of monocytes and macrophages (J. Chang et al., J. Virol. 70:7792-7803, 1996). Therefore, the stage in the replication cycle at which these host genetic influences act was investigated in a study using 8 pairs of ID twins and 10 pairs of sex- and age-matched unrelated donors (URDs). In the first phase of the study, blood monocytes and monocyte-derived macrophages (MDM) of ID twins and URDs were infected with 15 HIV type 1 strains. Four well-characterized primary isolates and HIV-BaL were then examined in more detail. The host cell genetic effect in MDM was exerted predominantly prior to complete reverse transcription, as the HIV DNA level and p24 antigen levels were concordant (r = 0.91, P = 0.0001) and similar between the pairs of ID twin pairs (r = 0.96, P = 0.0001) but discordant between URD pairs (r = 0.11, P = 0.3) in both phases of the study. To further examine genetic influence on viral entry, we examined the proportion of CCR5 membrane expression on MDM. As expected, there was wide variability in proportion of MDM expressing CCR5 among URDs (r = 0. 58, P = 0.2); however, this variability was significantly reduced between ID twin pairs (r = 0.81, P = 0.01). Differences in viral entry did not necessarily correlate with CCR5 expression, and only very low levels of CCR5 expression restricted HIV entry and production. In summary, the host cell genetic effect on HIV replication in macrophages appears to be exerted predominantly pre-reverse transcription. Although CCR5 was necessary for infection, other unidentified host genes are likely to limit productive infection.

Serologic survey for selected infectious disease agents in raccoons from Illinois

The determination of serologic titers to infectious organisms is a valuable tool for quantitating exposure to disease organisms. Raccoons (Procyon lotor) were live-trapped from September 1989 to October 1993 and samples collected from two distinct locations in west-central Illinois (USA); a state recreational facility (Park) and privately owned farming property (Farm). Sera were submitted for testing Leptospira interrogans (serovars bratislava, canicola, grippotyphosa, hardjo, icterohemmorhagiae, and pomona), canine distemper virus (CDV), pseudorabies virus (PV), and Toxoplasma gondii. Two-hundred and twenty-two (48%) of 459 raccoons were seropositive for L. interrogans. Eighty-five (23%) out of 368 raccoons were seropositive for canine distemper virus. Eighty-two (17%) of 479 raccoons raccoons were seropositive for pseudorabies virus. One hundred and eight-four (49%) of 379 raccoons were seropositive for T. gondii. A significant difference (P < 0.05) in seroprevalence for L. interrogans between the park (43%) and farm (52%) areas was found. A correlation between increasing age and seroprevalence was found for L. interrogans, CDV, PV, and T. gondii. Furthermore, there was a significant difference in seroprevalence for T. gondii during the spring trapping seasons (73%), when compared with the fall (33%). This type of information on exposure to infectious agents is important for developing control programs to manage raccoon-human and raccoon-domestic animals interactions.

A comparison of the angiotensin II antagonists valsartan and losartan in the treatment of essential hypertension

We compared the angiotensin II receptor antagonist valsartan to losartan as an antihypertensive agent in an 8-week trial. Adults with uncomplicated essential hypertension (baseline seated diastolic blood pressure < 115 mm Hg and > or = 95 mm Hg) were randomized to receive 80 mg valsartan, 50 mg losartan, or placebo once daily. After 4 weeks doses of active medication and placebo were doubled. Seated systolic and diastolic blood pressures were measured and the response rate evaluated. Tolerability was assessed by the incidence of adverse events. Both angiotensin II receptor antagonists produced similar significant reductions in mean blood pressures at 4 and 8 weeks compared to placebo. Valsartan produced a significantly higher number of responders (62%) than losartan (55%, P = .02) at the 8 week treatment endpoint. The incidence of adverse experiences (AE) was similar in all three groups, with headache and dizziness reported most often. Valsartan (80/160 mg) monotherapy in this trial was as effective and well tolerated as 50/100 mg losartan in treating mild to moderate essential hypertension, and at 160 mg has a significantly higher responder rate than 100 mg losartan.

Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO4(2)-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and without kerosene space heaters

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.

Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO4(2)-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and without kerosene space heaters

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.