Effects of Candesartan vs Lisinopril on Neurocognitive Function in Older Adults With Executive Mild Cognitive Impairment: A Randomized Clinical Trial

IMPORTANCE

Observational studies have suggested that angiotensin receptor blockers are associated with a unique cognitive protection. It is unclear if this is due to reduced blood pressure (BP) or angiotensin receptors type 1 blockade.

OBJECTIVE

To determine neurocognitive effects of candesartan vs lisinopril in older adults with mild cognitive impairment (MCI).

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial included participants aged 55 years or older with MCI and hypertension. Individuals were withdrawn from prior antihypertensive therapy and randomized in a 1 to 1 ratio to candesartan or lisinopril from June 2014 to December 2018. Participants underwent cognitive assessments at baseline and at 6 and 12 months. Brain magnetic resonance images were obtained at baseline and 12 months. This intent-to-treat study was double-blind and powered for a sample size accounting for 20% dropout. Data were analyzed from May to October 2019.

INTERVENTIONS

Escalating doses of oral candesartan (up to 32 mg) or lisinopril (up to 40 mg) once daily. Open-label antihypertensive drug treatments were added as needed to achieve BP less than 140/90 mm Hg.

MAIN OUTCOMES AND MEASURES

The primary outcome was executive function (measured using the Trail Making Test, Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research tool) and secondary outcomes were episodic memory (measured using the Hopkins Verbal Learning Test-Revised) and microvascular brain injury reflected by magnetic resonance images of white matter lesions.

RESULTS

Among 176 randomized participants (mean [SD] age, 66.0 [7.8] years; 101 [57.4%] women; 113 [64.2%] African American), 87 were assigned to candesartan and 89 were assigned to lisinopril. Among these, 141 participants completed the trial, including 77 in the candesartan group and 64 in the lisinopril group. Although the lisinopril vs candesartan groups achieved similar BP (12-month mean [SD] systolic BP: 130 [17] mm Hg vs 134 [20] mm Hg; P = .20; 12-month mean [SD] diastolic BP: 77 [10] mm Hg vs 78 [11] mm Hg; P = .52), candesartan was superior to lisinopril on the primary outcome of executive function measured by Trail Making Test Part B (effect size [ES] = -12.8 [95% CI, -22.5 to -3.1]) but not Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research score (ES = -0.03 [95% CI, -0.08 to 0.03]). Candesartan was also superior to lisinopril on the secondary outcome of Hopkins Verbal Learning Test-Revised delayed recall (ES = 0.4 [95% CI, 0.02 to 0.8]) and retention (ES = 5.1 [95% CI, 0.7 to 9.5]).

CONCLUSIONS AND RELEVANCE

These findings suggest that in older adults with MCI, 1-year treatment with candesartan had superior neurocognitive outcomes compared with lisinopril. These effects are likely independent of the BP-lowering effect of candesartan.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01984164.

Respiratory Syncytial Virus-Associated Hospitalizations Among Young Children: 2015-2016

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalized acute respiratory illness (ARI) among young children. With RSV vaccines and immunoprophylaxis agents in clinical development, we sought to update estimates of US pediatric RSV hospitalization burden.

METHODS

Children <5 years old hospitalized for ARI were enrolled through active, prospective, population-based surveillance from November 1, 2015, to June 30, 2016, at 7 US pediatric hospital sites. Clinical information was obtained from parent interviews and medical records. Midturbinate nasal and throat flocked swabs were collected and tested for RSV by using molecular diagnostic assays at each site. We conducted descriptive analyses and calculated population-based rates of RSV-associated hospitalizations.

RESULTS

Among 2969 hospitalized children included in analyses, 1043 (35%) tested RSV-positive; 903 (87%) children who were RSV-positive were <2 years old, and 526 (50%) were <6 months old. RSV-associated hospitalization rates were 2.9 per 1000 children <5 years old and 14.7 per 1000 children <6 months old; the highest age-specific rate was observed in 1-month-old infants (25.1 per 1000). Most children who were infected with RSV (67%) had no underlying comorbid conditions and no history of preterm birth.

CONCLUSIONS

During the 2015-2016 season, RSV infection was associated with one-third of ARI hospitalizations in our study population of young children. Hospitalization rates were highest in infants <6 months. Most children who were RSV-positive had no history of prematurity or underlying medical conditions, suggesting that all young children could benefit from targeted interventions against RSV.

Racial Disparity in Cerebrospinal Fluid Amyloid and Tau Biomarkers and Associated Cutoffs for Mild Cognitive Impairment

IMPORTANCE

Prior evidence suggests that racial differences exist in tau biomarkers in mild cognitive impairment (MCI) and Alzheimer disease (AD). Whether this reported disparity is associated with a differential level of neurodegeneration and disease stage or with underlying mechanisms separate from amyloid or tau is unclear.

OBJECTIVES

To compare cerebrospinal fluid (CSF) biomarkers in African American and white individuals with normal cognition and MCI, to estimate race-based cutoffs for these biomarkers that maximize diagnostic discrimination between normal cognition and MCI, and to study the association of demographic characteristics, cognitive performance, and common vascular risk factors with these differences.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study conducted from March 1, 2016, through January 31, 2019, included participants in the Brain Stress Hypertension and Aging Research Program cohort undergoing baseline assessment. Participants were 50 years or older and recruited from the Atlanta, Georgia, area.

EXPOSURES

Self-reported race and cognitive status categorized using modified Petersen criteria and clinical consensus diagnosis.

MAIN OUTCOMES AND MEASURES

Levels of β-amyloid 1-42 (Aβ1-42), tau, and phosphorylated tau 181 (pTau181), the ratio of tau or pTau181 to Aβ1-42, and hippocampal volume on magnetic resonance imaging of the brain.

RESULTS

Data from 362 study participants were analyzed (mean [SD] age, 65.6 [7.9] years), of whom 152 (42.0%) were African American, 230 (63.5%) were women, and 189 (52.2%) had MCI. After adjustment for demographic characteristics and cognitive performance, lower mean (SE) levels were observed in African American vs white individuals with MCI for tau (52.40 [5.90] vs 78.98 [5.02] pg/mL; P = .001) and pTau181 (15.42 [2.06] vs 25.24 [1.75] pg/mL; P = .001) and a lower pTau181 to Aβ1-42 ratio (0.07 [0.02] vs 0.14 [0.01]; P = .003). There were no racial differences in the normal cognition group or in hippocampal volumes in the MCI group. Cutoffs for CSF biomarkers were higher for Aβ1-42 in African American relative to white individuals (208 [95% CI, 126-321] vs 197 [95% CI, 183-245] pg/mL) and lower for tau (51 [95% CI, 31-59] vs 59 [95% CI, 56-92] pg/mL) and pTau181 (12 [95% CI, 12-19] vs 20 [95% CI, 12-27] pg/mL) levels. Cutoffs for the pTau181 to Aβ1-42 ratio were 0.05 (95% CI, 0.03-0.12) for African American participants and 0.05 (95% CI, 0.05-0.13) for white participants.

CONCLUSIONS AND RELEVANCE

This study found that African American individuals had lower levels of tau-based biomarkers that were not likely explained by the degree of disease stage or neurodegeneration reflected by hippocampal volumes. This study suggests that race is an important factor when interpreting CSF biomarkers, especially in the clinical diagnosis of prodromal AD. It appears that using the pTau181 to Aβ1-42 ratio may ameliorate these differences.

UTILITY OF EXECUTIVE FUNCTION TO IDENTIFY EARLY COGNITIVE IMPAIRMENT IN AFRICAN AMERICANS

Within diverse cohorts, African Americans (AA) demonstrate higher rates of Alzheimer’s dementia (AD) and Alzheimer’s dementia combined with multiple comorbid conditions. AA are also two times more likely to develop late-onset AD than whites and less likely to be diagnosed. Yet, our understanding of this disparity in cognition remains limited. Cognitive impairment (CI) and dementia are both underdiagnosed and underreported in primary care patients. The lack of early detection of cognitive and functional decline in high risk populations results in failure to provide care and interventions to members of vulnerable groups. This talk will focus on research that seeks to identify a more sensitive cognitive marker for early identification of cognitive impairment for AA and advances this objective by linking the cognitive marker to AD cerebral spinal fluid biomarkers (Aβ1-42, p-tau) and testing whether this association differs between AA and whites.

The Impacts of Residential Location on the Risk of HIV Virologic Failure Among ART Users in Durban, South Africa

Using a case-control study of patients receiving antiretroviral treatment (ART) in 2010-2012 at McCord Hospital in Durban, South Africa, we sought to understand how residential locations impact patients' risk of virologic failure (VF). Using generalized estimating equations to fit logistic regression models, we estimated the associations of VF with socioeconomic status (SES) and geographic access to care. We then determined whether neighborhood-level poverty modifies the association between individual-level SES and VF. Automobile ownership for men and having non-spouse family members pay medical care for women remained independently associated with increased odds of VF for patients dwelling in moderately and severely poor neighborhoods. Closer geographic proximity to medical care was positively associated with VF among men, while higher neighborhood-level poverty was positively associated with VF among women. The programmatic implications of our findings include developing ART adherence interventions that address the role of gender in both the socioeconomic and geographical contexts.

751. Acute Respiratory Illness Hospitalizations Among Young Children: Multi-Center Viral Surveillance Network, United States, 2015–2016

Background

Viral infections are a significant cause of severe acute respiratory illnesses (ARI) in young children. Understanding the current epidemiology of these viruses is important for informing treatment and prevention measures. We describe the New Vaccine Surveillance Network (NVSN) and report preliminary results from 2015 to 2016.

Methods

Prospective active surveillance for hospitalized ARI was conducted from November 1, 2015 to June 30, 2016 among children <5 years of age at seven pediatric hospital sites (figure) using a broad case definition based on admission diagnoses. Parent interviews and medical chart reviews were performed, and mid-turbinate nasal and throat flocked swabs and/or tracheal aspirates were tested for adenovirus, human metapneumovirus (HMPV), influenza, parainfluenza viruses (PIV) 1–3, respiratory syncytial virus (RSV), and rhinovirus/enterovirus using molecular diagnostic assays at each site. Asymptomatic controls <5 years of age were also enrolled.

Results

Among 2,974 hospitalized children with ARI whose specimens were tested for viruses, 2,228 (75%) were <2 years old, with 745 (25%) 0–2 months, and 309 (10%) 3–5 months old. The majority were male (58%; n = 1,732) and 63% (n = 1,093) had no documented comorbid conditions. The median length of stay was 2 days; 1,683 (57%) received supplemental oxygen, 435 (15%) were admitted to intensive care, 95 (3%) required mechanical ventilation, and 1 (<1%) died. Viruses were detected in 2,242 (75%) children with ARI, with >1 virus detected in 234 (8%). RSV was detected in 1,039 (35%) children with ARI, HMPV in 245 (8%), influenza in 104 (4%), and PIV-1, PIV-2, and PIV-3 in 49 (2%), 2 (<1%), and 78 (3%), respectively. Rhinovirus/enterovirus was detected in 849 (29%) and adenovirus in 118 (4%) children with ARI, but were also detected in 18% (n = 227) and 5% (n = 60), respectively, of the 1,243 controls tested; the other viruses were more rarely detected in controls.

Conclusion

During the 2015–2016 season, viral detections were common in young children hospitalized for ARI at seven US sites. NVSN combines clinical data with current molecular laboratory techniques to describe respiratory virus epidemiology in cases of hospitalized pediatric ARI in order to inform current and future prevention, treatment, and healthcare utilization measures.

Disclosures

N. Halasa, Sanofi Pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee. J. Englund, Gilead: Consultant and Investigator, Consulting fee and Research support. Novavax: Investigator, Research support. GlaxoSmithKline: Investigator, Research support. Alios: Investigator, Research support. MedImmune: Investigator, Research support. J. V. Williams, Quidel: Board Member, Consulting fee. GlaxoSmithKline: Consultant, Consulting fee.

Prevalence of Human Papillomavirus Among Females After Vaccine Introduction-National Health and Nutrition Examination Survey, United States, 2003-2014

Background

Human papillomavirus (HPV) vaccine was recommended in 2006 for routine vaccination of US females aged 11-12 years. Most vaccine used through 2014 was quadrivalent vaccine (4vHPV), which prevents HPV-6, -11, -16, and -18 infection. To evaluate vaccine impact, we measured HPV prevalence in the National Health and Nutrition Examination Survey (NHANES).

Methods

We analyzed HPV DNA types detected in self-collected cervicovaginal specimens and demographic, sexual behavior, and self-reported vaccination data from females 14-34 years old. We estimated HPV prevalence in the prevaccine (2003-2006) and vaccine eras (2007-2010 and 2011-2014).

Results

Among 14- to 19-year-olds, 4vHPV-type prevalence decreased from 11.5% (95% confidence interval [CI], 9.1%-14.4%) in 2003-2006 to 3.3% (95% CI, 1.9%-5.8%) in 2011-2014, when ≥1-dose coverage was 55%. Among 20- to 24-year-olds, prevalence decreased from 18.5% (95% CI, 14.9%-22.8%) in 2003-2006 to 7.2% (95% CI, 4.7%-11.1%) in 2011-2014, when ≥1-dose coverage was 43%. Compared to 2003-2006, 4vHPV prevalence in sexually active 14- to 24-year-olds in 2011-2014 decreased 89% among those vaccinated and 34% among those unvaccinated. Vaccine effectiveness was 83%.

Conclusions

Within 8 years of vaccine introduction, 4vHPV-type prevalence decreased 71% among 14- to 19-year-olds and 61% among 20- to 24-year-olds. Estimated vaccine effectiveness was high. The decrease in 4vHPV-type prevalence among unvaccinated females suggests herd protection.

Novel Predictors of Poor Retention Following a Down-Referral from a Hospital-Based Antiretroviral Therapy Program in South Africa

Worldwide, HIV care is becoming increasingly decentralized. For patients in care at centralized facilities, this requires down-referral to local clinics for their HIV care. Information on the real-world experience and predictors of retention in care at the time of down-referral is lacking. We sought to evaluate the effect of patient-level factors on retention in care surrounding a period of down-referral to new clinics for patients with and without virologic failure (VF) on their first-line ART. We conducted a secondary analysis of a case-control study of people living with HIV attending the Sinikethemba (SKT) Clinic at McCord Hospital in Durban, South Africa. Cases (VF) and controls (no VF) responded to a questionnaire focused on individual-level factors. Subsequently, participants self-reported either changing service provider (retained in care), were unable to be reached, died or reported not attending a new provider visit (not retained in care). Multivariate logistic regression was conducted with factors associated with not being retained in care in a univariate analysis. In all, 458 patients were enrolled in the parent study (158 cases and 300 controls) with a median age of 38 years old and with 65% women. A total of 436 (95%) participants successfully established care at the down-referral clinic. In the multivariate analysis, not being pleased with the clinic (SKT), lower adherence scores, and shorter duration of ART predicted failure of down-referral. Down-referral was successful even for patients with VF. Individual-level factors could act as predictors for patients at increased risk for poor retention during the down-referral process to a local clinic.

Experimental evidence for a minimalist account of English resumptive pronouns

In this article we provide evidence for a Minimalist account of English-type resumptive pronouns. Our findings provide empirical support for syntactic theories that, like Minimalist accounts, allow for competition among derivations. According to our account, resumptive pronouns are spell-outs of traces. For reasons of economy, the resumptive pronoun surfaces only when the derivation with the trace is precluded by syntactic principles. This account predicts that resumptive pronouns should only improve violations of constraints on representation, and not violations of constraints on movement. We tested this prediction by conducting an acceptability judgment task with 36 native speakers of English. The results bore out our prediction; subjects preferred the resumptive pronoun over the trace in cases where the trace itself was illicit, but not in cases where only the movement operation was illicit.

Dose-response relationships for disposition and hepatic sequestration of polyhalogenated dibenzo-p-dioxins, dibenzofurans, and biphenyls following subchronic treatment in mice

Humans are exposed to mixtures of polyhalogenated dibenzo-p-dioxins, dibenzofurans, and biphenyls mainly through the diet. Many of these chemicals are dioxin-like and their relative toxicity is related to their ability to bind and activate the Ah receptor. The present study examines the structure-activity relationship for disposition of these chemicals in female B6C3F1 mice following subchronic exposures. Mice were treated 5 days/week for 13 weeks by oral gavage with different doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD),2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1-PeCDF), 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF), octachlorodibenzofuran (OCDF), 3,3',4,4',5-pentachlorobiphenyl (126), 3,3',4,4',5,5'-hexachlorobiphenyl (169), 2,3,3',4,4'-pentachlorobiphenyl (105), 2,3',4,4',5-pentachlorobiphenyl (118), and 2,3,3',4,4',5-hexachlorobiphenyl (156). All of the chemicals examined exhibited dose-dependent increases in the liver/fat concentrations except PCBs 105, 118, and 156. While TCDD is the most potent toxicant in this class of chemicals, 4-PeCDF, PeCDD, OCDF, TCDF, and PCB126 were sequestered in hepatic tissue to a greater extent than was TCDD. The high affinity for hepatic tissue supports the presence of an inducible hepatic binding protein for some dixin-like chemicals. The differences in disposition between these chemicals suggests that pharmacokinetic differences between congeners is important in the relative potency of these chemicals.

Relatives children say

In an experiment designed to elicit restrictive relatives clauses, 28 children ranging in age from 2; 2 to 3; 10 provided a corpus of communicatively appropriate relative clauses. In evaluating this corpus, we found that most children produced mostly adult relative clauses most of the time. Detailed study of these utterances uncovered a few error patterns, which we analyzed in light of several considerations (e.g. the overall frequency of an error type, its distribution across children and items, its relation to the construction under study, and the similarity of the error to what children do elsewhere). Only one error pattern, namely some children's production of inappropriate relative pronouns, is argued to reflect a systematic feature of language development. We conclude that children's ability to represent the syntactic structure of the embedded clause is on target very early.

Determination of 2,3,7,8-chlorine-substituted dibenzo-p-dioxins and -furans at the part per trillion level in United States beef fat using high-resolution gas chromatography/high-resolution mass spectrometry

As part of the U.S. EPA Dioxin Reassessment Program, the 2,3,7,8-chlorine-substituted dibenzo-p-dioxins and furans were measured at part per trillion (ppt) levels in beef fat collected from slaughter facilities in the United States. This is the first statistically designed national survey of these compounds in the U.S. beef supply. Analyte concentrations were determined by high-resolution gas chromatography/high-resolution mass spectrometry, using isotope dilution methodology. Method limits of detection on a whole weight basis were 0.05 ppt for TCDD and 0.10 ppt for TCDF, 0.50 ppt for the pentas (PeCDDs/PeCDFs)/hexas (HxCDDs/HxCDFs)/heptas (HpCDDs/HpCDFs), and 3.00 ppt for the octas (OCDD/OCDF). Method detection and quantitation limits were established on the basis of demonstrated performance criteria utilizing fortified samples rather than by conventional signal-to-noise or variability of response methods. The background subtraction procedures developed for this study minimized the likelihood of false positives and increased the confidence associated with reported values near the detection limits. Mean and median values for each of the 2,3,7,8-Cl-substituted dioxins and furans are reported, along with the supporting information required for their interpretation. The mean toxic equivalence values for the samples are 0.35 ppt (nondetects = 0) and 0.89 ppt (nondetects = 1/2 LOD).

Hypothyroidism--a possible etiology of open-angle glaucoma

BACKGROUND

Recent studies have shown an association between hypothyroidism and primary open-angle glaucoma (POAG). When hypothyroidism occurs, accumulation of hyaluronic acid within the trabecular meshwork may cause an increase in outflow resistance and intraocular pressure (IOP). This increase may be reversible with use of systemic treatment.

METHODS

A hypothyroid patient is described whose IOP inversely varied with the use or the discontinuation of systemic hypothyroid medications.

RESULTS

The patient's IOP was controlled when she complied with systemic treatment.

CONCLUSIONS

In some cases, hypothyroidism may contribute to the genesis of open-angle glaucoma. Systemic treatment alone may be adequate to prevent progression of a glaucomatous diseased state. It may be prudent to investigate the presence of undiagnosed hypothyroidism in individuals with poorly controlled POAG, in individuals with normal-tension glaucoma, and in newly diagnosed cases.

A statistical survey of dioxin-like compounds in United States beef: a progress report

The USEPA and the USDA have completed the first statistically designed survey of the occurrence and concentration of CDDs and CDFs in the fat of beef animals raised for human consumption in the United States. Back fat was sampled from 63 carcasses at federally inspected slaughter establishments nationwide. The sample design called for sampling beef animal classes in proportion to national annual slaughter statistics. All samples were analyzed using a modification of EPA method 1613, using isotope dilution, High Resolution GC/MS to determine the rate of occurrence of 2,3,7,8-substituted CDDs/CDFS. The whole weight method detection limits ranged from 0.05 ng kg-1 for TCDD to 3 ng kg-1 for OCDD. The results of this survey showed a mean concentration (reported as I-TEQ, lipid adjusted) in U.S. beef animals of 0.35 ng kg-1 and 0.89 ng kg-1 when either non-detects are treated as 0 value or assigned a value of 1/2 the detection limit, respectively.

In vitro and in vivo evaluations of A-80556, a new fluoroquinolone

A-80556 is a novel fluoroquinolone with potent antibacterial activity against gram-positive, gram-negative, and anaerobic organisms. A-80556 was more active than ciprofloxacin, ofloxacin, lomefloxacin, and sparfloxacin against gram-positive bacteria. A-80556 was particularly active against Staphylococcus aureus (MIC for 90% of isolates [MIC90], 0.12 microgram/ml, relative to fluoroquinolone-susceptible strains) and Streptococcus pneumoniae (MIC90, 0.12 microgram/ml). A-80556 was also the most active of the quinolones tested against ciprofloxacin-resistant S. aureus, with an MIC90 of 4.0 micrograms/ml; that of ciprofloxacin was > 128 micrograms/ml. However, the significance of this activity is not known. A-80556 was slightly less active against Escherichia coli (MIC90, 0.06 microgram/ml) and other enteric organisms than ciprofloxacin (MIC90 for E. coli, < or = 0.03 microgram/ml). A-80556 was slightly less active against Pseudomonas aeruginosa (MIC90, 4.0 micrograms/ml) than ciprofloxacin (MIC90, 2.0 micrograms/ml) and more active against Acinetobacter spp. (respective MIC90s, 0.12 and 0.5 microgram/ml). A-80556 was also the most active compound against anaerobes. Against Bacteroides fragilis, the MIC90 of A-80556 was 2.0 micrograms/ml; that of ciprofloxacin was 16 micrograms/ml. The in vivo efficacy of A-80556 in experimental models with both gram-positive and gram-negative infections was consistent with the in vitro activity and pharmacokinetics and oral absorption in mice.

Basal-level expression of the yeast HSP82 gene requires a heat shock regulatory element

Previous studies have shown that heat shock factor is constitutively bound to heat shock elements in Saccharomyces cerevisiae. We demonstrate that mutation of the heat shock element closest to the TATA box of the yeast HSP82 promoter abolishes basal-level transcription without markedly affecting inducibility. The mutated heat shock element no longer bound putative heat shock factor, either in vitro or in vivo, but still resided within a nuclease-hypersensitive site in the chromatin. Thus, constitutive binding of heat shock factor to heat shock elements in S. cerevisiae appears to functionally direct basal-level transcription.

In vitro and in vivo activities of clarithromycin against Mycobacterium avium

There is no effective therapy to treat Mycobacterium avium complex infection in patients with acquired immune deficiency syndrome. Clarithromycin (A-56268; TE-031) is a new macrolide which is twofold more active than erythromycin against most aerobic bacteria. In addition, higher levels in serum and tissue are achieved with clarithromycin than with erythromycin. In this study, clarithromycin, erythromycin, difloxacin, temafloxacin, ciprofloxacin, rifampin, amikacin, and ethambutol were tested in vitro and in vivo against the M. avium complex. The MICs for 90% of strains tested were 4 micrograms/ml for clarithromycin, 64 micrograms/ml for erythromycin, 32 micrograms/ml for difloxacin, 8 micrograms/ml for temafloxacin, 4 micrograms/ml for ciprofloxacin, 4 micrograms/ml for rifampin, 32 micrograms/ml for amikacin, and 32 micrograms/ml for ethambutol. Beige mice were infected intravenously with 10(7) CFU of M. avium ATCC 25291. Treatment was started on day 6 after infection and was administered twice a day at 8-h intervals for 9 days. Clarithromycin was the most effective compound in these tests and was effective in reducing the viable bacterial counts in the spleen when it was administered subcutaneously or orally at a dose of 25 mg/kg. Amikacin was the only other compound which showed activity in vivo. The peak concentration in serum at which clarithromycin was active was approximately 1.0 microgram/ml.

Coumamidines, new broad spectrum antibiotics of the cinodine type. III. Microbiologic activity of coumamidine gamma 1

The coumamidines are novel antibiotics with activity against a wide spectrum of aerobic Gram-positive and Gram-negative bacteria. All microbiological studies were performed on coumamidine gamma 1. The MIC90s (micrograms/ml) of coumamidine are as follows: Staphylococcus aureus 1.0, Streptococcus pyogenes 8, Enterobacteriaceae 2.0, Pseudomonas aeruginosa 8, Campylobacter jejuni and Campylobacter coli 1, Legionella pneumophila 8, Haemophilus influenzae 0.5, Neisseria gonorrhoeae 0.5. Coumamidine had MICs ranging from 8 to greater 0.5, Neisseria gonorrhoeae 0.5. Coumamidine had MICs ranging from 8 to greater than 64 for most anaerobes, except some Peptostreptococcus strains. The aminoglycoside super-sensitive strain, P. aeruginosa BMH 10, was also super-sensitive to coumamidine (MIC 0.2 micrograms/ml). Coumamidine was rapidly bactericidal for S. aureus. The viable bacterial count in logarithmic phase cultures was reduced to less than 10 cfu within 2 hours after exposure to 4 times the MIC (3.12 micrograms/ml) of coumamidine. The frequency of resistance development was less than 1 X 10(-9) for Escherichia coli and S. aureus when selected at 4 and 8 times the MIC. The Cmax in mouse serum after a single subcutaneous dose of 25 mg/kg of coumamidine was 4.5 micrograms/ml and t1/2 was 1 hour. Coumamidine is stable in serum. In mouse protection tests against S. aureus NCTC 10649 the ED50 was less than 0.6 mg/kg/day when it was administered subcutaneously at 1 and 5 hours after infection. Coumamidine was not absorbed after oral administration. The antibacterial spectrum, bactericidal activity, stability in serum and low frequency of resistance make this an interesting new class of antibiotics.

Histiocytosis X and acute monocytic leukemia. Biologic illustration of the monocyte phagocytic system

The concept of a mononuclear phagocytic system consisting of a continuum of cells arising from the bone marrow monoblast and terminating in the mature tissue macrophage is being actively investigated. The presentation of documented acute monocytic leukemia 18 months following the confirmed diagnosis of histiocytosis X in a 39-year-old man strongly supports the concept of the mononuclear phagocytic system lineage.

Digital subtraction angiography of the extremities using table translation

Digital subtraction angiography (DSA) of the extremities has been performed with both intravenous and intraarterial injections of contrast material. Intravenous studies are usually site specific and are limited by contrast material load; a complete intraarterial study with multiple injections of contrast material may be time consuming. A feasibility study to evaluate a DSA technique that would allow table translation and imaging of two contiguous regions following a single injection of contrast material--bolus-chase DSA--was performed. Forty-five examinations were performed, 13 intravenously and 32 intraarterially. Twelve intravenous and 16 intraarterial DSA examinations were totally satisfactory. Inadequate studies were predominantly caused by slow arterial clearance of contrast material in the distal calf and by operator error. Compared with conventional DSA, anatomic studies of lower-extremity vessels could be obtained faster and with lower contrast material loads using bolus-chase DSA.

Similar effects by valine and isoleucine on threonine deaminase

Isoleucine is known to be a very effective inhibitor and stabilizer of threonine deaminase. In contrast, valine has been reported to be a positive effector for the enzyme by action on a separate site. However, the apparent increase in activity caused by valine is due to stabilization of the enzyme. When stabilization is accomplished by other means, valine exerts only an inhibitory effect. Thus, valine, like isoleucine, both stabilizes and inhibits threonine deaminase and may well do so via the isoleucine site on the enzyme.