Effects of preterm birth, maternal ART and breastfeeding on 24-month infant HIV-free survival in a randomized trial

BACKGROUND

IMPAACT 1077BF/FF compared the safety/efficacy of two HIV antiretroviral therapy (ART) regimens to zidovudine (ZDV) alone during pregnancy for HIV prevention. PROMISE found an increased risk of preterm delivery (<37 weeks) with antepartum triple ART (TDF/FTC/LPV+r or ZDV/3TC/LPV+r) compared to ZDV alone. We assessed the impact of preterm birth, breastfeeding and antepartum ART regimen on 24-month infant survival.

METHODS

We compared HIV-free and overall survival at 24-months for liveborn infants by gestational age, time-varying breastfeeding status, and antepartum ART arm at 14 sites in Africa and India. Kaplan-Meier survival probabilities and Cox proportional hazards ratios (HR) were estimated.

RESULTS

3,482 live-born infants (568 [16 3%] preterm and 2,914 [83 7%] term) were included. Preterm birth was significantly associated with lower HIV-free survival (0·85; 95% CI: 0·82-0·88) and lower overall survival (0·89; 95% CI: 0·86-0·91) versus term birth (0·96; 95% CI: 0·95-0·96). Very preterm birth (<34 weeks) was associated with low HIV-free survival (0·65; 95% CI: 0·54-0·73) and low overall survival (0·66; 95% CI: 0·56-0·74). Risk of HIV infection or death at 24-months was higher with TDF-ART than ZDV-ART (adjusted HR 2·37; 95% CI: 1·21-4·64). Breastfeeding initiated near birth decreased risk of infection or death at 24 months (adjusted HR 0·05; 95% CI: 0·03-0·08) compared to not breastfeeding.

CONCLUSION

Preterm birth and antepartum TDF-ART were associated with lower 24-month HIV-free survival compared to term birth and ZDV-ART. Any breastfeeding strongly promoted HIV-free survival, especially if initiated close to birth. Reducing preterm birth and promoting infant feeding with breastmilk among HIV/ARV-exposed infants remain global health priorities.

Association Between Anterior Nasal and Plasma SARS-CoV-2 RNA Levels and Hospitalization or Death in Nonhospitalized Adults With Mild-to-Moderate COVID-19

BACKGROUND

There is little information regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA as a predictor for clinical outcomes in outpatients with mild-to-moderate coronavirus disease 2019 (COVID-19).

METHODS

Anterior nasal (AN) and plasma SARS-CoV-2 RNA data from 2115 nonhospitalized adults who received monoclonal antibodies (mAbs) or placebo in the ACTIV-2/A5401 trial were analyzed for associations with hospitalization or death.

RESULTS

One hundred two participants were hospitalized or died through 28 days of follow-up. Higher day 0 (pretreatment) AN RNA was associated with increasing risk of hospitalization/death (risk ratio [RR], 1.24 per log10 copies/mL [95% confidence interval {CI}, 1.04-1.49]) among placebo recipients, ranging from 3% to 16% for <2 to ≥6 log10 copies/mL. Although only 1% had quantifiable levels, there was a similar trend across day 0 plasma RNA categories. Higher day 3 AN RNA was associated with subsequent hospitalization/death among placebo recipients (RR, 1.42 per log10 copies/mL [95% CI, 1.00-2.03]), but not mAb recipients (RR, 1.02 per log10 copies/mL [95% CI, 0.68-1.56]). The proportion of treatment effect (reduction in hospitalizations/deaths after day 3 for mAb vs placebo) explained by day 3 AN RNA was 8%.

CONCLUSIONS

SARS-CoV-2 RNA levels are predictive of hospitalization/death in the natural history setting, but AN RNA levels may not be a reliable surrogate marker of mAb treatment effect in COVID-19 trials. Clinical Trials Registration. NCT04518410.

Safety and Efficacy of Combination SARS-CoV-2 Neutralizing Monoclonal Antibodies Amubarvimab Plus Romlusevimab in Nonhospitalized Patients With COVID-19

BACKGROUND

Development of safe and effective SARS-CoV-2 therapeutics is a high priority. Amubarvimab and romlusevimab are noncompeting anti-SARS-CoV-2 monoclonal antibodies with an extended half-life.

OBJECTIVE

To assess the safety and efficacy of amubarvimab plus romlusevimab.

DESIGN

Randomized, placebo-controlled, phase 2 and 3 platform trial. (ClinicalTrials.gov: NCT04518410).

SETTING

Nonhospitalized patients with COVID-19 in the United States, Brazil, South Africa, Mexico, Argentina, and the Philippines.

PATIENTS

Adults within 10 days onset of symptomatic SARS-CoV-2 infection who are at high risk for clinical progression.

INTERVENTION

Combination of monoclonal antibodies amubarvimab plus romlusevimab or placebo.

MEASUREMENTS

Nasopharyngeal and anterior nasal swabs for SARS-CoV-2, COVID-19 symptoms, safety, and progression to hospitalization or death.

RESULTS

Eight-hundred and seven participants who initiated the study intervention were included in the phase 3 analysis. Median age was 49 years (quartiles, 39 to 58); 51% were female, 18% were Black, and 50% were Hispanic or Latino. Median time from symptom onset at study entry was 6 days (quartiles, 4 to 7). Hospitalizations and/or death occurred in 9 (2.3%) participants in the amubarvimab plus romlusevimab group compared with 44 (10.7%) in the placebo group, with an estimated 79% reduction in events (P < 0.001). This reduction was similar between participants with 5 or less and more than 5 days of symptoms at study entry. Grade 3 or higher treatment-emergent adverse events through day 28 were seen less frequently among participants randomly assigned to amubarvimab plus romlusevimab (7.3%) than placebo (16.1%) (P < 0.001), with no severe infusion reactions or drug-related serious adverse events.

LIMITATION

The study population was mostly unvaccinated against COVID-19 and enrolled before the spread of Omicron variants and subvariants.

CONCLUSION

Amubarvimab plus romlusevimab was safe and significantly reduced the risk for hospitalization and/or death among nonhospitalized adults with mild to moderate SARS-CoV-2 infection at high risk for progression to severe disease.

PRIMARY FUNDING SOURCE

National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

878. Association between Anterior Nasal and Plasma SARS-CoV-2 RNA Levels and Hospitalization or Death for Non-Hospitalized Adults with Mild-to-Moderate COVID-19

Background

Data are currently limited on the performance of SARS-CoV-2 RNA levels as predictors or surrogate markers for clinical outcomes in outpatients with mild-to-moderate COVID-19.

Methods

This exploratory analysis used data from 2205 non-hospitalized adults who enrolled between August 2020 and July 2021 and participated in placebo-controlled evaluations of two monoclonal antibody (mAb) agents (bamlanivimab [n=317] or amubarvimab/romlusevimab [n=837]), and an open-label cohort of bamlanivimab recipients [n=1051] as part of the ACTIV-2/A5401 platform trial. SARS-CoV-2 RNA levels were measured in anterior nasal (AN) swabs and plasma at day 0 (pre-treatment) and AN at day 3. We fit regression models to estimate the association between RNA level or detection and subsequent hospitalization/death within 28 days of enrollment.

Results

One-hundred four participants (53/571 [9%] on placebo and 51/1634 [3%] on mAb) died or were hospitalized through day 28. Median AN RNA levels were lower at day 3 compared to day 0 in both placebo (2.5 vs 4.0 log₁₀ copies/mL [cp/mL]) and mAb (2.3 vs 4.9) groups. For placebo recipients, higher Day 0 AN RNA was associated with an increasing risk of hospitalization/death, ranging from 3% to 16% for < 2 and ≥ 6 log₁₀ cp/mL, respectively. Although only 1% had quantifiable plasma SARS-CoV-2 RNA, there was a similar trend for day 0 plasma RNA: 5% hospitalizations/death for undetectable RNA, 16% for detectable but not quantifiable RNA, and 80% for ≥ 2 log₁₀ cp/mL. Among 485 placebo recipients with days 0 and 3 AN RNA results, the risk of subsequent hospitalization/death was highest among those with ≥ 5.0 log₁₀ cp/mL at both days [8/78; 10%] and lowest for those with unquantifiable levels at both days [0/124; 0%]. Higher AN RNA at day 3 (adjusted for day 0 RNA) was associated with subsequent hospitalization/death among placebo recipients (relative risk (RR): 1.4 per log₁₀ cp/mL; 95%CI: 1.0, 2.1), but not mAb recipients (RR: 1.0; 95%CI: 0.7, 1.6).

Conclusion

These findings suggest that AN and plasma SARS-CoV-2 RNA levels are predictive of hospitalization/death in the natural history setting. However, different associations for mAb and placebo recipients raises concerns for using AN RNA as a surrogate for clinical outcomes in mAb trials.

Disclosures

Kara W. Chew, M.D., M.S., Merck Sharp & Dohme: Grant/Research Support|Pardes Bioscences: Advisor/Consultant Joseph J. Eron, MD, GSK: Advisor/Consultant|Merck: Advisor/Consultant Jonathan Z. Li, MD, MMSc, Abbvie: Advisor/Consultant|Merck: Grant/Research Support William A. Fischer, II, MD, Janssen: Adjudication Committee (Influenza)|Merck: Advisor/Consultant|Ridgeback Biopharmaceuticals: Research funding provided to the University of North Carolina|Roche: Advisor/Consultant|Syneos: Adjudication committee (Influenza) Paul Klekotka, MD, PhD, Eli Lilly: Employee|Eli Lilly: Stocks/Bonds David A. Margolis, MD MPH, Brii Biosciences: Stocks/Bonds David A. Wohl, M.D., Gilead: Advisor/Consultant|Gilead: Grant/Research Support|Lilly: Grant/Research Support|ViiV: Advisor/Consultant|ViiV: Grant/Research Support Eric S. Daar, M.D., Gilead: Advisor/Consultant|Gilead: Grant/Research Support|Merck: Advisor/Consultant|ViiV: Advisor/Consultant|ViiV: Grant/Research Support Davey M. Smith, M.D., M.A.S., Arena Pharmaceuticals: Advisor/Consultant|Bayer Pharmaceuticals: Advisor/Consultant|Brio Clinical.: Advisor/Consultant|Fluxergy: Advisor/Consultant|Kiadis: Advisor/Consultant|Linear Therapies: Advisor/Consultant|Matrix BioMed: Advisor/Consultant|Model Medicines: Advisor/Consultant|Signant Health: Advisor/Consultant|VxBiosciences: Advisor/Consultant Judith S. Currier, M.D., MSc, Merck: Advisor/Consultant.

Pharmacokinetics of Tenofovir Alafenamide With Boosted Protease Inhibitors in Pregnant and Postpartum Women Living With HIV: Results From IMPAACT P1026s

BACKGROUND

Tenofovir alafenamide (TAF) is a key component of HIV treatment, but pharmacokinetic data supporting the use of TAF during pregnancy are limited. In this study, we report pharmacokinetic, safety, and birth outcomes for TAF 25 mg with a boosted protease inhibitor in pregnant women living with HIV.

METHODS

IMPAACT P1026s was a multicenter, nonrandomized, open-label, phase IV prospective study. Pregnant women living with HIV receiving TAF 25 mg with a boosted protease inhibitor were eligible. Intensive pharmacokinetic assessments were performed during the second and third trimesters and 6-12 weeks postpartum. Maternal and cord blood samples were collected at delivery. Infant washout samples were collected through 5-9 days postbirth. Comparisons of paired pharmacokinetic data between pregnancy and postpartum were made using geometric mean ratios (GMR) [90% confidence intervals (CIs)] and Wilcoxon signed-rank tests with P < 0.10 considered significant.

RESULTS

Twenty-nine women were enrolled from the United States (median age 31 years and weight 84.5 kg during the third trimester; 48% Black, 45% Hispanic/Latina). TAF AUCtau did not significantly differ in the second [GMR 0.62 (90% CI: 0.29 to 1.34); P = 0.46] or third trimester [GMR 0.94 (90% CI: 0.63 to 1.39); P = 0.50] vs. postpartum and were comparable with historical data in nonpregnant adults. TAF was only quantifiable in 2/25 maternal delivery samples and below the limit of quantification in all cord blood and infant washout samples, likely because of the short half-life of TAF.

CONCLUSION

TAF AUCtau did not significantly differ between pregnancy and postpartum. These findings provide reassurance as TAF use during pregnancy continues to expand.

Effect on growth of exposure to maternal antiretroviral therapy in breastmilk versus extended infant nevirapine prophylaxis among HIV-exposed perinatally uninfected infants in the PROMISE randomized trial

Background

Malnutrition is highly prevalent in HIV-exposed perinatally uninfected infants (HEUs) increasing the risk of morbidity and mortality throughout the life course. We set out to compare the effect of postnatal exposure to maternal antiretroviral therapy (mART) in breastmilk versus infant Nevirapine prophylaxis (iNVP) on somatic growth of HEUs in the randomized PROMISE trial.

Methods and findings

We randomized 2431 mothers with HIV and their 2444 HEUs from six African countries and India 6–14 days after delivery to mART or iNVP for prevention of breastmilk HIV transmission. The mART regimen contained tenofovir/emtricitabine (99%) plus lopinavir/ritonavir. Infant growth parameters were compared at postnatal week 10, 26, 74 and 104 using World Health Organization (WHO) z-scores for length-for-age (LAZ), weight-for-age (WAZ), and head circumference-for-age (HCAZ). Week 26 LAZ was the primary endpoint measure. Student T-tests compared mean LAZ, WAZ, and HCAZ; estimated mean and 95% confidence interval (CI) are presented.

Maternal and infant baseline characteristics were comparable between study arms. The estimated median breastfeeding duration was 70 weeks. After a mean follow-up of 88 weeks, mean LAZ and WAZ were below the WHO reference population mean at all timepoints, whereas mean HCAZ was not. The mART and iNVP arms did not differ for the primary outcome measure of LAZ at week 26 (p-value = 0.39; estimated mean difference (95%CI) of -0.05 (-0.18, 0.07)) or any of the other secondary growth outcome measures or timepoints (all p-values≥0.16). Secondary analyses of the primary outcome measure adjusting for week 0 LAZ and other covariates did not change these results (all p-values≥0.09). However, infants assigned to mART were more likely to have stunting compared to iNVP infants at week 26 (odds ratio (95% CI): 1.28 (1.05, 1.57)).

Conclusions

In HEUs, growth effects from postnatal exposure to mART compared to iNVP were comparable for measures on length, weight and head circumference with no clinically relevant differences between the groups. Despite breastfeeding into the second year of life, length and weight were below reference population means at all ages in both arms. Further investment is needed to optimize postnatal growth of infants born to women with HIV.

Clinical trial registration

ClinicalTrials.gov number NCT01061151.

Pregnancy Outcomes of Women Conceiving on Antiretroviral Therapy (ART) Compared to Those Commenced on ART During Pregnancy

Background

Globally, the number of infected women of childbearing age living with human immunodeficiency virus (HIV) and conceiving on antiretroviral therapy (ART) is increasing. Evidence of ART safety at conception and during pregnancy and adverse pregnancy outcomes remains conflicting. The Promoting Maternal and Infant Survival Everywhere (PROMISE) 1077 breastfeeding (BF) and formula feeding (FF) international multisite trials provide an opportunity to examine the impact of ART at conception on pregnancy outcomes with subsequent pregnancies.

Methods

The PROMISE 1077BF/1077FF trials were designed to address key questions in the management of HIV-infected women who did not meet clinical guidelines for ART treatment during the time of the trials. After the period of risk of mother-to-child transmission was over, women were randomized to either continue or discontinue ART. We compared subsequent pregnancy outcomes of nonbreastfeeding women randomized to continue ART following delivery, or breastfeeding women randomized to continue ART following breastfeeding cessation who conceived while on ART to women randomized to discontinue ART, who restarted ART after pregnancy was diagnosed.

Results

Pregnancy outcomes of 939 subsequent pregnancies of 826 mothers were recorded. The intention-to-treat analyses showed increased incidence of low birth weight (<2500 g) for women who conceived while on ART (relative risk, 2.65 [95% confidence interval {CI}, 1.20–5.81]), and also a higher risk of spontaneous abortion, stillbirth, or neonatal death (hazard ratio, 1.40 [95% CI, .99–1.98]) compared to women who restarted ART after they were found to be pregnant during trial follow-up.

Conclusions

We found an increased risk for adverse pregnancy outcomes in women conceiving on ART, emphasizing the need for improved obstetric and neonatal care for this group.

Clinical Trials Registration

NCT01061151.

Pharmacokinetics of tenofovir alafenamide with and without cobicistat in pregnant and postpartum women living with HIV

OBJECTIVE

To evaluate the pharmacokinetics of tenofovir alafenamide (TAF) 10 mg with cobicistat and 25 mg without boosting in pregnant and postpartum women with HIV and to characterize TAF placental transfer and infant washout pharmacokinetics.

DESIGN

Open-label, multicenter phase IV prospective study of TAF pharmacokinetics during pregnancy, postpartum, delivery, and infant washout.

METHODS

Pregnant women receiving TAF 10 mg with cobicistat or TAF 25 mg without boosting as part of clinical care had intensive pharmacokinetic assessments performed during the second and third trimesters, and 6-12 weeks postpartum. Maternal and cord blood samples were collected at delivery, and washout pharmacokinetic samples were collected in infants. TAF concentrations were quantified using liquid chromatography/mass spectrometry. Comparisons between pregnancy and postpartum were made using geometric mean ratios (90% confidence intervals) and Wilcoxon signed-rank tests.

RESULTS

Thirty-one pregnant women receiving TAF 10 mg with cobicistat-boosting and 27 women receiving TAF 25 mg without boosting were enrolled. TAF exposures did not significantly differ between pregnancy and postpartum when administered as 10 mg with cobicistat. Antepartum TAF exposures with the 25 mg dose were 33-43% lower in comparison with postpartum, but comparable with those measured in nonpregnant adults. TAF was below the lower limit of quantitation in 43 of 44 cord blood, 41 of 45 maternal blood at delivery, and all infant washout samples.

CONCLUSION

TAF exposures were comparable or higher than those measured in nonpregnant adults during pregnancy and postpartum. These findings provide reassurance on adequate TAF exposures during pregnancy, and support efforts to expand the use of TAF in pregnant women with HIV.

Barriers to Health Insurance Pre- and Post-Affordable Care Act Implementation in Providence, RI

The impact of healthcare reform under the Affordable Care Act (ACA) on individuals living in cities has not yet been quantified by local Departments of Health. This makes it difficult for safety net sources of healthcare, such as free clinics, to plan for the future. Therefore, members of Clinica Esperanza/Hope Clinic conducted a survey in predominantly Latino communities of South and West Providence, RI, using a convenience sample method (N = 206). Survey results were compared to a prior survey conducted in the same communities prior to ACA implementation. Despite gains due to Obamacare, a much higher level of uninsurance was reported in this survey than has been reported statewide. In 2014, as compared to 2010, 48% vs. 95% of respondents reported being uninsured, and more held private (20% vs. 5%) or government-subsidized health insurance (32% vs. 1%). Undocumented immigration status and cost were the two most commonly reported reasons for remaining uninsured under the ACA. First-generation immigrants living in urban centers are still reporting significantly higher rates of uninsurance (48%) than the general population in RI (7.4%).

Short communication: Biological and genetic characterization of HIV type 1 subtype B and nonsubtype B transmitted viruses: usefulness for vaccine candidate assessment

Due to the extraordinary degree of genetic diversity of HIV-1 and the structural complexity of its envelope glycoproteins, designing an effective vaccine is difficult, requiring the development of viral reagents to assess vaccine-elicited neutralizing antibodies. The aim of this study was to improve on our previously developed panel of HIV-1 strains of different genetic forms, focusing on strains from acute and recently acquired infections as the most representative of the transmitted viruses. HIV-1 primary isolates were expanded in peripheral blood mononuclear cells. Viral stocks of 40 ml each were produced. Syncytium-inducing (SI) phenotype, coreceptor use, and TCID(50)/ml were determined. Near full-length HIV-1 genomes were amplified by RT-nested PCR in four overlapping segments. Phylogenetic analyses were performed with neighbor-joining trees and bootscanning. Forty-four HIV-1 strains were included in the panel. Twenty-four (54.1%) strains were from early infections (16 acute and 8 recent); of them, 21 (87%) were sexually transmitted. NSI/R5 phenotype was detected in 37 (84.1%) viruses and SI/R5,X4 in another 7 (15.9%). TCID(50)/ml ranged between 10(4) and 10(6.6). Twelve different genetic forms constituted this panel: subtypes A1, B, C, F1, and G; circulating recombinant forms CRF02_AG, CRF14_BG, and CRF24_BG; and unique recombinant forms CRF02_AG/A3, BF1, CRF12_BF/B, and DF1G. In conclusion, in this study, we report the development of a comprehensive and well-characterized panel of HIV-1 isolates for assessing neutralization in HIV vaccine research. This panel is available for distribution through the Programme EVA Centre for AIDS Reagents, National Institute for Biological Standard and Control (NIBSC).

Zoonotic transmission of Streptococcus equi subsp. zooepidemicus from a dog to a handler

This is, to the best of our knowledge, the first case report to describe the apparent transmission of Streptococcus equi subsp. zooepidemicus from an infected dog to a handler who subsequently developed severe systemic infection. Characterization of the haemolytic streptococci isolated from both the patient and the dog, by phenotypic and molecular analysis, confirmed the canine and human isolates were identical.

Incidence of non-B subtypes of HIV-1 in Galicia, Spain: high frequency and diversity of HIV-1 among men who have sex with men

An increase in HIV transmission among men who have sex with men (MSM) has been reported in eight regions of Spain from 2003 to 2007. In order to study the incidence of HIV-1 genetic forms in Galicia, northwest of Spain, in particular the spread of HIV-1 variants among MSM, 93 newly diagnosed HIV-1 patients, including those with acute and recently acquired infections, were studied for a year from August 2008 to August 2009. Thirty eight (41%) were MSM. Of them, nine (24%) were infected by non-B viruses, including seven different genetic forms. The analysis of transmission clusters showed that 23 (60%) MSM grouped in different clusters and mostly in large clusters. Resistance mutations were detected in six (16%) MSM.

Development of a panel of well-characterized human immunodeficiency virus type 1 isolates from newly diagnosed patients including acute and recent infections

The aim of this study was the development of a panel constituted by well-defined HIV-1 strains of different genetic forms, with a particular focus on isolates from acute and recent infections. Fourteen HIV-1 isolates, including four from acute and five from recent infections, were expanded in peripheral blood mononuclear cells. SI phenotype, coreceptors use, and TCID(50)/ml were determined. V3 net charge was calculated. Near full-length genomes were amplified by RT-nested PCR in four overlapping segments. Phylogenetic analyses were performed with neighbor-joining trees and bootscanning. Analysis of cysteine residues, lengths of variable regions, and potential N-linked glycosylation sites in gp120 and gp41 was performed. Viral stocks were produced. Thirteen strains were NSI/R5 and one SI/R5,X4. TCID(50)/ml ranged between 10(4.6) and 10(6). V3 net charge was <+5 in 12 sequences and +5 in two sequences. Near full-length HIV-1 genomes analysis identified viruses of the following genetic forms: eight subtype B, three subtype C, two CRF02_AG, and one subtype G. Cysteine residues that form the V1,V2,V3, and V4 loops were highly conserved. The number of potential N-linked glycosylation sites in gp120 and gp41 ranged between 24-29 and 4-6, respectively. Seven potential N-linked glycosylation sites in gp120 and three in gp41 were conserved. V1, V2, V4, and V5 variable regions exhibited substantial length variation. In addition, an analysis of transmitted and natural resistance to current antiretroviral drugs in these strains was performed. It is worth mentioning that the 13S mutation in the V3 sequence, associated with resistance to maraviroc, was observed in a subtype B strain that harbored resistance mutations to nucleoside reverse transcriptase inhibitors and to T20. The availability of a panel including strains from acute and recent infections should be a valuable resource for optimizing and standardizing vaccine candidate assessment. Near full-length genome characterization may be necessary for evaluating clade-specific reactivities.

Long-term monitoring of genotypic and phenotypic resistance to T20 in treated patients infected with HIV-1

The aim of this study was to investigate the susceptibility to T20 and the dynamics of amino acid changes in HR1 and HR2 of gp41 of HIV-1 obtained from plasma, peripheral blood mononuclear cells (PBMC), and primary isolates (PI) in four highly antiretroviral-experienced patients. These patients received T20 plus an antiretroviral regimen and were followed-up over a period of 40-72 weeks. In one non-responder patient, N43D substitution was detected at 12 weeks of treatment, in association with a value of T20-IC50 of 10 microg/ml (10-fold increase). Double mutations N42T + N43D were observed in plasma RNA at 32 weeks and remained detectable up to 16 weeks after the withdrawal of the drug. The S138A substitution in HR2 was observed in plasma RNA at 32 weeks, and both in plasma RNA and in PI DNA at 40 weeks, associated with an increase of the T20-IC50 to 25 microg/ml (25-fold increase). Mutations V101G and E137K, not reported previously, were also observed in the HR2 region. Whether these new substitutions play a role in T20 resistance needs to be examined. In three temporary responders, coinciding with viral load rebound, G36D, and N42T substitutions were observed at 12, 24, and 40 weeks. G36D mutation was associated with a value of T20-IC50 of 5 microg/ml. The HR2 S138A mutation was detected after the detection of HR1 substitutions and was associated with an increase in the level of T20-IC50 to 125 microg/ml (125-fold increase) All these data reinforce the role of gp41 amino acids 36-45 and the potential influence of the HR2 S138A mutation in the genotypic/phenotypic resistance to T20.

Development of interface in hydroxyapatite implanted in the middle ear of the rat: a light and scanning microscopy study

OBJECTIVE

The aim of this work is to study the chronology in the biological covering of the hydroxyapatite bioprostheses in the healthy middle ear of the rat.

STUDY DESIGN AND SETTING

Dense hydroxyapatite is implanted into the middle ear of 45 Long-Evans rats, between stapes and tympanic membrane. The sample was divided into 3 groups for morphologic, functional, and chemical studies at 15 days, 3 months, and 6 months after surgery, respectively.

RESULTS

The short-term studies reveal that the prostheses is surrounded by a fibrous epithelial tissue referred as the interface; it presents a marked inflammatory reaction that decreases gradually in the medium-term and long-term studies; in this way, we observe a progressive adhesion between implant and the contact tissues.

CONCLUSIONS AND SIGNIFICANCE

This model has enabled us to study the cell reaction produced by the contact of the prostheses with bone and soft tissue and their impact on the functional qualities of the prostheses.

Management of N0 neck in laryngeal carcinoma. Impact on patient's survival

Management of patients with carcinoma of the larynx should systematically include an appropriate treatment of lymph nodes according to the TNM stage. One of the most controversial points of the treatment in these patients is the management of the clinically negative neck (N(0)). A retrospective study of 295 patients with laryngeal carcinoma and N(0) neck undergoing treatment in our centre between 1983 and 1993 is presented. We observed a significant decrease in the survival of clinically N(0) patients with histologically affected lymph nodes. Lymphadenopathy was more frequently detected in patients with supraglottic tumours (38 per cent) when compared to glottic tumours (16 per cent). In our experience, routine bilateral and unilateral dissection of N(0) necks in all supraglottic tumours and in T3-T4 glottic tumours, respectively, is the most beneficial approach for patients in terms of survival.

Cirugía endoscópica nasosinusal: revisión de 1.093 casos

We present a serie of 1,093 patients that underwent, along 10 years, endoscopic surgery due to paranasal sinus pathology in a third level hospital. The technique used is described, the long term results analysed, as well as the minor and major complications specially the CSF fistulas and their cause.

Ventral approach to the rat middle ear for otologic research

OBJECTIVE

To describe a simple approach to the rat middle ear because there are few clear descriptions of this technique with minimal morbidity and mortality.

STUDY DESIGN AND SETTING

Six male Long-Evans rats were used in this study. We designed a cervical approach to the middle ear with the purpose of creating an experimental model of ossiculoplasty that permits the postoperative survival of the animal.

RESULTS

It was possible in all cases to visualize the majority of structures of the tympanic cavity: promontory, round window, stapedial artery, stapes, incus, and tympanic membrane. There were no cases of postoperative infection or facial paralysis.

CONCLUSIONS AND SIGNIFICANCE

The ventral approach to the rat middle ear is a rapid and simple technique that makes the rat the animal of choice for many otologic investigations.

[Cervical lymph node involvement in laryngeal carcinoma: a retrospective study of 430 cases]

Cervical lymph node involvement in laryngeal tumors could be a market impact on the disease prognosis. We performed a retrospective study of 430 patients who underwent surgery to treat laryngeal carcinoma in our center over a 10-year period. The objective was to correlate clinical and pathological lymph node involvement with the site of origin and size of the tumor, the treatment and its impact on patient survival. We observed a significantly greater incidence of lymph node involvement in tumors originating from supraglottis, with a rate of occult lymph node metastases of 31%. Patients with lymphadenopathy that remained undetected in the absence of surgical treatment and those with nonmetastatic lymphadenopathy presented similar 5-year survival rates, 83% y 98% respectively. However, the 5-year survival decreased to 24% in the presence of metastatic lymph node involvement. These results support the proposal that treatment of laryngeal carcinoma should include the region of the cervical nodes as well.

Mouse erythrocytes as carriers for coencapsulated alcohol and aldehyde dehydrogenase obtained by electroporation in vivo survival rate in circulation, organ distribution and ethanol degradation

Alcohol dehydrogenase and aldehyde dehydrogenase (ADH and ALDH) have been coencapsulated into mouse erythrocytes by an electroporation technique. The optimal conditions were achieved as follows: 420 V, four pulses of 1 ms every 15 min. at 37 degrees C, completed by resealing: 1 h at 37 degrees C. An encapsulation yield ranging from 11-12% was obtained for ADH+ALDH-loaded erythrocytes. Carrier cell recovery was 52%. Electroporated-RBCs observed under Scanning electron microscopy exhibited a tendency toward invaginated sphero-stomatocytes. These invaginations were not found in electroporated/resealed RBCs. The intravenous administration of 51Cr-RBCs manifested a bimodal pharmacokinetic profile: an initial phase (t1/2alpha) with a rapid decrease of plasma 51Cr-RBCs followed by a slow and prolonged elimination phase (t1/2beta). The values corresponding to in vivo survival rate during the elimination phase indicated that the survival rate of 51Cr-electroporated loaded-RBCs was slightly lower (t1/2beta, 4.5 days) than 51Cr-native RBCs (t1/2beta, 5.3 days). The mean clearance values from blood of electroporated 51Cr-RBCs (unloaded and loaded) were higher (0.51 %51Cr/day and 0.54 %51Cr/day, respectively) than the obtained for native 51Cr-RBCs (0.18 %51Cr/day). The target organs for electroporated RBCs proved to be the same as for native RBCs. However, electroporated RBCs showed highest accumulation in liver, spleen and lung, since they were promptly recognized by the reticuloendothelium system. Mice induced to the state of acute ethanol intoxication and treated with ADH+ALDH-RBCs clearly showed a lower level of ethanol concentration in plasma (less than 43% ethanol) than the intoxicated mice treated with native RBCs. En consequence the clearance values of ethanol from blood in intoxicated mice treated with ADH+ALDH-RBCs (0.39 ml/min) were higher than the treated with native RBCs (0.20 ml/min). The results obtained suggest that ADH+ALDH-loaded erythrocytes could be used as a potential carrier system for in vivo removal of high levels of ethanol from blood caused by excessive alcohol consumption.

In vitro and in vivo study of glutamate dehydrogenase encapsulated into mouse erythrocytes by a hypotonic dialysis procedure

Glutamate dehydrogenase (GDH) has been encapsulated into mouse erythrocytes by a hypotonic dialysis/isotonic resealing method. Although a low GDH entrapment yield was achieved (3.8%), this percentage appeared sufficient enough to metabolize high quantities of ammonia. Carrier cell recovery yield was 56%. Due to the decrease in cell volume and haemoglobin content, constant mean cell haemoglobin concentration (MCHC) values were obtained. The osmotic fragility curves (OFC) indicated that dialyzed/resealed-RBCs are more resistant to hypotonic haemolysis than native-RBCs. The successful in vitro ammonia degradation by GDH-RBCs was reflected in its total disappearance from the incubation medium at around 48 h. In contrast, initial ammonia levels were not affected during the incubation in the presence of native-RBCs and remained constant. Two different methods were used for the preparation of hyperammonaemic mice model. Since the intraperitoneal (i.p.) administration of ammonium acetate produced high ammonia levels that lasted only a few minutes, the i.p. administration of urease was chosen, given that it generated elevated ammonia levels for longer periods of time. Hyperammonaemic mice quickly removed high levels of circulating ammonia in the presence of GDH-RBCs, whereas in the presence of native-RBCs ammonia was slowly metabolized. These results suggest that loaded GDH-erythrocytes can be used as a potential carrier systems for the in vivo removal of high levels of ammonia from blood.

In vivo survival of selected murine carrier red blood cells after separation by density gradients or aqueous polymer two-phase systems

In order to explore possibilities of using erythrocytes as carrier systems for delivery of pharmacological agents, we have studied the in vivo survival of murine carrier red blood cell populations enriched in young or old cells. Hypotonic-isotonic dialysis has been used to modify the cells as carrier systems and Percoll/albumin density gradients or counter-current distribution in aqueous polymer two-phase systems to separate them according to age. Hypotonic-isotonic dialysis produces a decrease in the red blood cell populations in vivo survival rate (from 9.5 to 7.8 days). Among the cells modified as carriers, the enriched young red blood cell populations show a higher in vivo survival (half-life 6.5-7.4 days) than populations made up of predominantly old red blood cells (half-life 4.7-6.2 days). Half-life of young or old circulating red blood cells was approximately one day longer when these cells were separated by counter-current distribution rather than by Percoll density gradients. Based on these results, hypotonic-isotonic dialysis of whole and enriched young or old red blood cell populations, with higher or lower survival rates, can be considered as a useful tool for modification of these cells as carriers. The final outcome of such changes can be translated into better control of plasma drug delivery during therapy.

[Retrospective study of complications of surgery for laryngeal cancer]

Surgery, alone or in combination with other therapeutic measures, is one of the main approaches to curing laryngeal cancer. The risk of complications is implicit in any surgical procedure. We describe our experience with general and local complications in surgery for laryngeal cancer and examine their relation to tumor extension and surgical technique. A review was made of a series of 431 patients who underwent surgery for laryngeal cancer over a 10-year period (1982-1991). Twenty-two patients (5.1%) had systemic complications, including upper gastrointestinal hemorrhage (n = 5), massive cervical hemorrhage (n = 5), and four renal failure. Minor complications were recorded in 77 cases (17.8%), predominantly pharyngocutaneous salivary fistula, which developed in 55 patients (13.8%). The incidence of local complications was significantly greater in patients with extensive local spread (T4). There were no differences among patients with regional spread. The surgical technique and type of pharyngoesophageal reconstruction played no role in the development of complications. Preoperative radiotherapy did not influence on the development of salivary fistulas.

[Oncologic surgery of the larynx after failure of radiotherapy]

The treatment of early-stage laryngeal cancer using either partial surgical techniques or irradiation still is controversial. The performance of rescue surgical procedures after irradiation is related to increased postsurgical complications and lower survival rates. We made a retrospective study of 73 patients who underwent rescue surgery after failure of radiotherapy in our department in the last 10 years. A statistical analysis was made of the complications and survival rate of these patients in accordance with tumor location and clinicopathological stage compared with patients who underwent surgery alone (n = 435). More rescue surgery was performed for glottic carcinomas (52/73) than for supraglottic carcinomas (21/73). No significant differences were found in the complication rate (23.6%) compared with the control group (19.6%). There was a significant reduction in survival in patients who underwent previous irradiation of supraglottic tumors compared with glottic tumors and the control group. In view of these results, we conclude that irradiation is not a good option as an initial treatment for supraglottic tumors and that the procedure of choice should be surgical.

In vitro study of alcohol dehydrogenase and acetaldehyde dehydrogenase encapsulated into human erythrocytes by an electroporation procedure

The optimal conditions for electroporated/resealed loading of alcohol dehydrogenase (ADH) and/or acetaldehyde dehydrogenase (ALDH) into human erythrocytes were established prior to the study, with the following characteristics: 300 V, 1 ms pulse time, eight pulses every 15 min and 1 h resealing at 37 degreesC. High encapsulation yield and carrier cell recoveries were achieved. Cell volumes increase while hemoglobin contents decrease; in consequence a decrease in cell hemoglobin concentration was observed. A lower hypotonic resistance of loading erythrocytes (throughout osmotic fragility curves) and unaltered oxygen transport capability (as given by oxygen equilibrium curves) were observed. The stability against time (up to 168 h-7 days) of encapsulated individual enzymes, either ADH- or ALDH-red blood cells (RBCs), was studied at 4 degreesC and 37 degreesC, in comparison with that of free enzyme solutions. Both enzymes were released from carrier RBCs to the incubation medium. The stability of carrier RBCs was studied under similar conditions. Non-significant variations in hematological parameters were observed. However, the hemoglobin derivative forms showed modifications. The continuous degradation of ethanol by ADH-RBCs and coencapsulated ADH- and ALDH-RBCs, as a function of time (up to 70 h) suggests the use of these carrier RBCs as agents for complete metabolization of ethanol. The mentioned properties bare the possibility of using ADH and ALDH as carrier systems in in vivo situations.

A comparative study by a single chromatographic procedure of glycolytic regulatory kinase isozymes in rat erythroid cells as a function of differentiation-maturation process

The isozymes of three glycolytic regulatory kinases: hexokinase, phosphofructokinase and pyruvate kinase are fractionated by a single ion exchange chromatographic procedure on DEAE-cellulose. Enriched-erythroblast bone marrow cells showed two heterogeneous peaks, each consisting of two overlapping peaks: one major and one minor peak, but only two isozymes were observed in reticulocytes and erythrocytes. Phosphofructokinase showed multiple isozymic forms in the three cell populations, but while in erythroblasts the main one eluted in the last fractions, in reticulocytes and erythrocytes it eluted in the early fractions. Pyruvate kinase showed a main early activity peak with a shoulder in erythroblasts, reticulocytes and erythrocytes but the response to the allosteric effectors (fructose-1,6-bisphosphate and ATP) suggests the presence of different pyruvate kinase isozymes in reticulocytes and erythrocytes.

Surface and metabolic properties of microcytic and macrocytic human anaemic red blood cells detected in polymer aqueous two-phase systems

Microcytic and macrocytic red blood cells from anaemic patients have been fractionated as a function of cell surface properties by the countercurrent distribution technique using charge-sensitive dextran/poly(ethylene glycol) aqueous two-phase systems. As deduced from the fractionation profiles, microcytic cells constitute a heterogeneous cell population with decreased surface charge properties while. macrocytic cells constitute a homogeneous cell population with behaviour similar to that of the control red blood cells. The specific activity of pyruvate kinase, an age-dependent enzyme, did not change along microcytic red blood cells fractionation profiles, suggesting that such cells have altered ageing properties. However, pyruvate kinase specific activity decreases from the left- to the right-hand side of the fractionation profile of macrocytic red blood cells, indicating that these cells follow the normal ageing process. Bisphosphoglycerate mutase specific activity did not change along the fractionation profile of any cell population under study, thus providing 2,3-bisphosphoglycerate during the life-span of the red blood cells from anaemic patients.

Chondrosarcoma of the temporal bone and otosclerosis

Chondrosarcoma constitutes 6% of all primary bone tumors and 11% of malignant primary bone tumors. Nevertheless, in a review of the tumor registry of the University of Michigan covering a period of 50 years, there were only 3 cases involving the temporal bone. A case of a woman with a chondrosarcoma of the temporal bone that was partially resected by means of an infratemporal approach at the skull base is presented. This patient had previously undergone surgical treatment for otosclerosis of the other ear. Several considerations regarding survival factors in this type of tumor are dealt with in terms of the histological features, therapeutic options and anatomic location. The possibility that this lesion may originate from the persistence of the cartilaginous inclusions that some authors consider to be involved in the origin of otosclerosis is discussed.

[Protocol for the endoscopic sinus surgery: comparative analysis of 200 cases]

A preliminary analysis was published in 1993 of 100 cases of endoscopic sinus surgery (ESS) carried out in our service following a protocol that included sinusitis, nasal polyps, and other endoscopic nasal procedures. Another 100 cases of ESS were analyzed for the present study and compared with the 1993 group. Comparative analysis showed improved results in the second series, with fewer minor complications and no major complications. These findings confirm the general opinion that endoscopic sinus surgery requires an adequate training period before optimal results are obtained.

Oxygenation capacity of hypotonized and crosslinked rat erythrocytes

Rat erythrocytes subjected to hypotonic-isotonic dialysis, or crosslinking with bifunctional reagents (glutaraldehyde and dimethyl suberimidate hydrochloride) show a high percentage of methemoglobin and decreased oxyhemoglobin content which implies a low oxygen carrying capacity. Such modified cells maintain reversible oxygen binding properties although, they present a high hemoglobin oxygen affinity (low P50) and a diminished cooperativity in binding oxygen to hemoglobin (low n). These results suggest a reduced capacity of liberating oxygen to tissues under low PO2. Changes produced in erythrocytes can not be restored even in the presence of energy (ATP), reduced glutathione and 2,3-bisphosphoglyceric acid during the dialysis process or after crosslinking/permeabilizing treatment.

Osteoma of the promontory: a case report

Osteomas of the middle ear are rare lesions. We report the case of a 20-year-old male with osteoma originating from the promontory coincident with tympanic membrane perforation. Histopathological diagnosis was performed by means of a superficial curettage during surgery, to avoid a cochlear fenestration. Postoperative closure of the air-bone gap after myringoplasty confirmed the presumed asymptomatic nature of these lesions.

[Synthetic implants in the reconstruction of the ossicular chain]

Experience has revealed a higher rate of functional failure of biocompatible prostheses used in the surgical reconstruction of the middle ear than was reported initially. The cause of these failures was analyzed in a retrospective study of 135 patients who underwent middle ear reconstructive procedures: 47 of them involved implantation of plastic prostheses. Proplast or Plastipore, and had a sufficient follow-up. We evaluated the prosthetic material and middle-ear conditions for which they were implanted.

Erythrocytes as carriers for recombinant human erythropoietin

PURPOSE

The aim of this work was to encapsulate recombinant human erythropoietin (rHuEpo) in human and mouse red blood cells (RBCs) to improve the stability of encapsulated rHuEpo.

METHODS

The encapsulation of rHuEpo was achieved by an hypotonic dialysis-isotonic resealing procedure. A radioimmunoassay method was used for the estimation of rHuEpo. The hypoosmotic resistance of carrier erytrhocytes was studied by osmotic fragility measurements. Cell morphology was observed under scanning electron microscopy. Encapsulated rHuEpo was identified by an immunogold labeling assay.

RESULTS

Encapsulation yields were 22% for human RBCs and 14% for mouse RBCs. Cell recovery was around 70%. Carrier-RBCs exhibited a tendency to spherocytic morphology, and showed the typical higher hypoosmotic resistance than normal RBCs. The presence of rHuEpo inside carrier RBCs was identified. The stability of encapsulated rHuEpo seems to be related to the experimental conditions used during the encapsulation procedure. An increase with time of released rHuEpo was observed in carrier-RBC suspensions.

CONCLUSIONS

The encapsulation of rHuEpo in RBCs has been achieved for the first time. These carrier RBC-preparations may serve as an alternative sustained cell delivery system for the in vivo administration of rHuEpo.

The influence of enzyme concentration on the encapsulation of glutamate dehydrogenase and alcohol dehydrogenase in red blood cells

Glutamate dehydrogenase (GDH) and alcohol dehydrogenase (ADH) have been encapsulated in sheep and human red blood cells (RBCs) by a hypotonic dialysis/isotonic resealing procedure. At a fixed enzyme level in the dialysis bag (100 units/ml of RBCs), a significant encapsulation yield was observed for ADH, both in human (17.2%) and sheep (47.9%) RBCs, whereas a very low entrapment of GDH was achieved (1-3%) in either species. Carrier cell recovery was 61-65% in humans and 30-34% in sheep. Because of the aggregation of GDH to large polymers at protein levels above 1 mg/ml, the yield of encapsulation and the specific activity in human carrier RBCs were compared at different enzyme concentrations. While entrapment was not affected by differences in ADH up to 13,000 units/ml of RBCs (38 mg/ml), the yield of GDH encapsulation significantly decreased as the enzyme level increased up to 750 units/ml of RBCs (15 mg/ml), thus demonstrating the importance of protein concentration in the encapsulation process for those enzymes that tend to aggregate.

Surface properties of crosslinked erythrocytes as studied by counter-current distribution in aqueous polymer two-phase systems

The bifunctional imidoester dimethyl suberimidate hydrochloride can stabilize rat red blood cells (RBCs) by membrane protein crosslinking, and in that way they can be used as carrier systems for exogenous substances. Counter-current distribution fractionation in charge-sensitive dextran-polyethyleneglycol two-phase systems has been used to detect slight changes in surface charge in stabilized cells. A decrease in the surface charge of crosslinked RBCs and an apparent masking of the age-related cell surface properties have been found to result from the protein crosslinking. Digitonin treatment used to permeabilize crosslinked RBCs produces a significant decrease of the cell surface charge while the age-related surface properties do not seem to be modified by the treatment.

[Endoscopic approach of antrochoanal polyps]

Antrochoanal polyps represent a particular pathology among nasosinusal polyposis. Since KILLIAN'S first report in 1906, several pathogenic mechanisms and surgical techniques have been described. Surgical removal of an antrochoanal polyp by the classic Caldwell-Luc approach has been reviewed since the beginning of the use of nasosinusal functional endoscopic surgery. We present 12 cases of antrochoanal polyps removed by this technique in our hospital, during the last three years, analyzing the results and complications of this endoscopic approach. We conclude that functional endoscopic surgery of the sinus for removal of antrochoanal polyps, is a recommendable surgical technique due to its efficiency and low morbidity.

[Acquired stenosis of the nasopharynx]

A case of scarring stenosis of the nasopharynx occurring in the fifth decade without previous medical history is presented. Transpalatal resection with a prolonged stent, produced patent nasal cavities, but the different studies performed did not establish the etiological diagnosis. A final stage of rhinoscleroma was suspected.

Density gradient separation of L-asparaginase-loaded human erythrocytes

L-Asparaginase has been encapsulated in human red blood cells using a hypotonic dialysis process. Erythrocytes loaded with L-Asparaginase were separated into eight fractions using a discontinuous Percoll density gradient. A minor cell subpopulation of low density cells and a major subpopulation of denser erythrocytes was obtained after hypotonic dialysis treatment, in both the absence or presence of L-Asparaginase. The encapsulated L-Asparaginase activity per resealed erythrocyte was higher in low-density cells and decreased progressively with increasing in cellular density.

Biochemical characterization of human erythrocytes fractionated by counter-current distribution in aqueous polymer two-phase systems

The fractionation of normal human erythrocytes by counter-current distribution (CCD) in charge-sensitive dextran-polyethylene glycol two-phase systems was confirmed and extended to red blood cells from heterozygous beta-thalassaemic patients. The differences between the distribution profiles of normal (homogeneous) and abnormal (heterogeneous) red blood cells reflect their different surface-charge properties. As suggested by the decline of membrane sialic acid released after neuraminidase treatment and the specific activities of two age-dependent enzymes (membrane acetylcholinesterase and intracellular pyruvate kinase) in the distribution profiles (from the left- to the right-hand side fractions), the fractionation seems to be according to red blood cell age. A constancy of the 2,3-bisphosphoglycerate level was observed in ageing red blood cells.

Surface properties of crosslinked and crosslinked-permeabilized erythrocytes as studied by partitioning in aqueous polymer two-phase systems

Non-charge- and charge-sensitive dextran/polyethyleneglycol two-phase systems have been used to study the surface properties of red blood cells stabilized by crosslinking with dimethyl suberimidate and permeabilized with digitonin. While crosslinked red blood cells show similar hydrophobic- and charge-related surface properties as control cells, the digitonin treatment changes their surface properties. The changes in hydrophobicity are related to the cell total lipid and cholesterol content while the changes in the charge are related to the sialic acid released by neuraminidase.

Properties of hypotonized, crosslinked and crosslinked- permeabilized rat erythrocytes as potential carrier systems

The osmotic fragility curves of isotonic rat RBCs, studied at pH 8 to avoid the Hb insolubility, are similar to those in humans at pH 7.4. Hypotonized rat RBCs, either directly or dialysed (0-24 h), are more hemolysis-resistant than isotonic rat RBCs. The discocyte-stomatocyte-spherocyte transformation can be observed with scanning electron microscopy. Protein crosslinking with dimethyl suberimidate can stabilize RBCs. The crosslinking level (60%), the cellular yield (80%), the mechanical and hemolytic resistance and the protective effect of enzyme activities, were studied in crosslinked or crosslinked- permeabilized RBCs after digitonin treatment. The normal discocytic shape of RBCs under scanning electron microscopy becomes stomatocytic in crosslinked and crosslinked- permeabilized RBCs with an erosioned surface.

Changes in glycolytic enzyme activities in aging erythrocytes fractionated by counter-current distribution in aqueous polymer two-phase systems

Human and rat erythrocytes were fractionated by counter-current distribution in charge-sensitive dextran/poly(ethylene glycol) two-phase systems. The specific activities of the key glycolytic enzymes (hexokinase, phosphofructokinase and pyruvate kinase) declined along the distribution profiles, although the relative positions of the activity profiles were reversed in the two species. These enzymes maintained their normal response to specific regulatory effectors in all cell fractions. No variations were observed for phosphoglycerate kinase and bisphosphoglycerate mutase activities. Some correlations between enzyme activities (pyruvate kinase/hexokinase, pyruvate kinase/phosphofructokinase, pyruvate kinase/pyruvate kinase plus phosphoglycerate kinase, pyruvate kinase/bisphosphoglycerate mutase and phosphoglycerate kinase/bisphosphoglycerate mutase ratios) were studied in whole erythrocyte populations as well as in cell fractions. These results strongly support the fractionation of human erythrocytes according to cell age, as occurs with rat erythrocytes.

Comparison of the PREMIER cryptococcal antigen enzyme immunoassay and the latex agglutination assay for detection of cryptococcal antigens

A new enzyme immunoassay (EIA), PREMIER Cryptococcal Antigen, was compared with latex agglutination (LA) for the detection and quantitation of circulating capsular polysaccharide antigen from Cryptococcus neoformans. The clinical evaluation of PREMIER EIA as a screening assay, including 475 specimens with 120 LA and EIA positives, resulted in 99% sensitivity and 97% specificity. The clinical specimens included sera and cerebrospinal fluids as well as 10 rheumatoid factor-positive and 20 anti-nuclear antibody-positive serum samples. This monoclonal antibody-based assay detects serotypes A to D at 0.63, 0.63, 7.8, and 62 ng/ml, respectively. With three different known positive specimens, the assay was found to yield coefficients of variation of 2 to 12% for intra- and interassay comparisons of precision and reproducibility. The primary use for semiquantitative values derived with the LA or EIA is to follow the course of disease and monitor drug therapies. The present data suggest that the PREMIER EIA will be a valuable method for this purpose. We conclude that the PREMIER Cryptococcal Antigen EIA provides a rapid, convenient, and reliable antigen detection method for screening and semiquantitative determination of antigen levels.

Fractionation in two-phase systems of red cells during rat development: changes in pyruvate kinase and bisphosphoglycerate mutase activities in relation to red cell switching

An inverse relationship between 2,3-bisphosphoglycerate levels and the ratio calculated from pyruvate kinase and bisphosphoglycerate mutase activities has been observed in red populations of rats during animal development. Counter-current distribution in aqueous two-phase systems of these cells populations shows a displacement of distribution profiles towards the high-numbered cavities of the rotor as animal ages. Heterogeneity of cells after distribution is only observed during the switching process from fetal to adult red cells taking place along the postnatal stage of development. Values for the pyruvate kinase/bisphosphoglycerate mutase ratio in these fractions suggest the separation of fetal (liver) from adult (bone marrow) red cells.