Hearing Outcomes in Cisplatin or Cetuximab Combined with Radiation for Patients with HPV-Associated Oropharyngeal Cancer in NRG/RTOG 1016

PURPOSE/OBJECTIVE(S)

NRG/RTOG 1016 was a noninferiority phase 3 trial comparing the efficacy of radiation with either cisplatin (RT+Cisp) or cetuximab (RT+Cetux) for patients with HPV+ oropharyngeal cancer (OPC). Perceived hearing handicap was included as a patient-reported outcome (PRO) secondary endpoint. The primary hypothesis was that perceived hearing handicap would be greater for patients receiving RT+Cisp compared to RT+Cetux.

MATERIALS/METHODS

Perceived hearing handicap was measured at baseline, end of treatment, 3, 6, and 12-months post-treatment using the Hearing Handicap Inventory for Adults Screening Version (HHIA-S), a 10-item self-assessment questionnaire designed to measure patients' reactions to their hearing loss. Total HHIA-S scores range from 0 to 40; higher total score indicates more severe perceived hearing handicap. Hearing handicap categories (none, mild/moderate, and severe) were also analyzed. Mixed ordinal logistic models were used to analyze the raw HHIA-S scores and handicap categories (2-sided alpha 0.05).

RESULTS

Participation in the PRO assessments was optional, with 368 patients participating in the hearing PRO. No significant differences in patient/tumor characteristics were found between PRO participants/non-participants. Pre-treatment (mean [SD]) HHIA-S scores were not different for RT+Cisp (3.23 [6.28]) and RT+Cetux (4.77 [8.14]) groups. Post-treatment HHIA-S scores increased for RT+Cisp, and remained stable at the later follow-up time points. RT+Cetux scores remained stable from baseline. Change score from pre- to post-treatment was higher for RT+Cisp (4.32, 95% CI = [2.57, 6.07]) than RT+Cetux (0.08, 95% CI = [-1.15, 1.31]; p < 0.001). For hearing handicap category, post-treatment RT+Cisp had a significantly higher percentage of mild/moderate and severe cases (32%) compared to RT+Cetux (20%). From pre- to post-treatment, worsening of hearing handicap category from normal to mild/moderate or severe was greater for RT+Cisp (24%) than for RT+Cetux (9%). The conditional odds of being in a higher self-perceived hearing handicap category in the RT+Cisp arm were 3.57 (95% CI [2.04, 6.25]) times that in the RT+Cetux arm. Averaging over patients, the marginal odds ratio was 2.46 (95% CI [1.65, 3.66]).

CONCLUSION

Patients receiving concurrent RT+Cisp for HPV-associated OPC have significantly higher odds of worsening self-perceived hearing handicap after treatment than with RT+Cetux. This was consistent across time through one-year post-treatment. These findings inform hearing-related outcomes for patients with HPV-associated OPC.

Planning Target Volume Margin Quantification of Retroperitoneal Tumors Using Robotic Stereotactic Body Radiotherapy with Spine Tracking

PURPOSE/OBJECTIVE(S)

Stereotactic body radiotherapy treatment (SBRT) is an effective modality for treating primary and oligometastatic malignant lesions. Appropriate planning target volume (PTV) margins are essential when delivering SBRT to maximize target prescription coverage while minimizing dose to surrounding organs-at-risk. Spine tracking uses boney spinal anatomy as a surrogate for tumor localization during treatment delivery on robotic linear accelerator platforms that employ intrafraction kV x-ray imaging. The aim of this study was to quantify the PTV margin needed when spine tracking was used for tumor localization when treating retroperitoneal metastatic lesions with robotic SBRT.

MATERIALS/METHODS

A single institution chart review was performed and identified 16 patients with retroperitoneal tumors treated stereotactically over 19 courses in 103 fractions. Daily cone-beam computed tomography (CBCT) images that were registered based on tumor position at the time of treatment were analyzed. Rigid registrations were re-performed aligning the position of the spine on the CBCT relative to its position on the planning CT. Shifts from the treatment position were recorded and per-patient mean shifts and standard deviations were calculated. Van Herk's margin recipe was used to determine the additional PTV margin required if spine tracking was used instead of soft tissue alignment. Patient tumors were stratified and compared based on proximity to the vertebral column (≤1 cm vs >1 cm) and location within the retroperitoneum (superior vs inferior to the renal artery). Student's t-test was used to compare statistical differences of shifts based on location.

RESULTS

The additional margins calculated by van Herk's margin recipe to adequately cover the target volumes within the 95% isodose surface for 90% of the entire patient cohort in the vertical, longitudinal, and lateral directions were 2.7, 2.8, and 2.8 mm, respectively. When tumors were stratified by proximity to the vertebral column, average longitudinal (p<0.001) and total shifts (p<0.001) were statistically significant. Isometric PTV expansions of 3, 4, and 5 mm would have encompassed 55%, 76%, and 86% of the maximum total shifts for lesions >1 cm from the vertebral column versus 94%, 100%, and 100% for lesions ≤1 cm. When stratified by location within the retroperitoneum, isometric PTV expansions of 3, 4, and 5 mm would have encompassed 82%, 94%, and 100% of the maximum total shifts for lesions superior to the renal artery versus 78%, 94%, and 98% for lesions inferior to the renal artery.

CONCLUSION

When treating retroperitoneal tumors with robotic SBRT, a minimum isometric margin expansion between 3 to 5 mm when creating the PTV is recommended if spine tracking is used for intrafraction tumor localization. Target volumes adjacent to the vertebral column may have PTV margins decreased to ≤4 mm without compromising target coverage.

The KRAS-Variant and Cetuximab in HPV-Positive Oropharyngeal Cancer in NRG/RTOG 1016

PURPOSE/OBJECTIVE(S)

NRG/RTOG 1016 was a non-inferiority phase III trial comparing radiation with cisplatin versus cetuximab monotherapy for patients with HPV-positive oropharyngeal squamous cell carcinoma (SCC). The trial did not meet the non-inferiority criteria for overall survival (OS) and had significantly worse progression-free survival (PFS) and locoregional failure (LRF) in patients treated with cetuximab. Based on prior evidence that HNSCC patients with a germ-line mutation in KRAS (the KRAS-variant) had a positive response to radiation with cisplatin plus cetuximab without increased toxicity, samples from RTOG 1016 were used to test the protocol-specified hypothesis that KRAS-variant patients will have better outcomes when receiving IMRT + cetuximab monotherapy compared to IMRT + cisplatin.

MATERIALS/METHODS

The KRAS-variant was tested in 562 samples at MiraDx, a CLIA-certified laboratory. OS, PFS, LRF, and distant metastases (DM) were as defined per the RTOG 1016 protocol, and hazard ratios (HRs) were estimated by (cause-specific) Cox models. Negative binomial regression was used to model the number of treatment-related acute and late (≤ and > 180 days from end of treatment, respectively) grade 3-5 adverse events. To assess the predictive role of the KRAS-variant, all models included KRAS, assigned treatment, and their interaction, with the interaction tested at two-sided 0.05. HRs and toxicity ratios are expressed as IMRT + cetuximab / IMRT + cisplatin.

RESULTS

The prevalence of the KRAS-variant was 16% with similar patient and tumor characteristics and well-balanced treatment arms for variant and non-variant patients. Median follow-up was 8.6 years. There was no significant interaction between KRAS and treatment for OS (p = 0.99), PFS (p = 0.56), LRF (p = 0.09), or DM (p = 0.19) (Table 1). In KRAS-variant patients the mean acute and late toxicity ratios were 0.53 (95% CI 0.36, 0.80) and 1.62 (95% CI 0.57, 4.62). In non-variant patients, the mean acute and late toxicity ratios were 0.80 (95% CI 0.67, 0.95) and 0.55 (95% CI 0.35, 0.87), respectively. The interaction of KRAS and treatment was not significant for acute (p = 0.07) or late toxicity (p = 0.07).

CONCLUSION

While this study does not directly refute prior evidence that KRAS-variant patients benefit from radiation + cisplatin and cetuximab, this study does not support the hypothesis that the KRAS-variant is a predictive biomarker of improved outcome in HPV+ oropharyngeal SCC patients treated with IMRT + cetuximab alone, and suggests that for KRAS-variant patients, potential benefits in LRF and acute toxicity with cetuximab may be offset by worse DM and worse late toxicity.

Pentoxifylline and Vitamin E in Preventing Pneumonitis Using Stereotactic Ablative Radiotherapy in Previously Irradiated Patients

PURPOSE/OBJECTIVE(S)

Despite radiotherapeutic advancements, patients with non-small cell lung cancer (NSCLC) experience recurrence rates from 30-40% (1) (2). For these cases, stereotactic ablative radiotherapy (SABR) is an attractive retreatment option as studies have reported upwards of 96% local control rates at 3 years follow up (3) (4). However, thoracic reirradiation poses threat for radiation-induced pneumonitis. Particularly, the rate of grade 3 pneumonitis from institutional data was 30% in patients undergoing SABR for recurrent thoracic malignancies (4). Prior studies have tried to mitigate SABR toxicities with administration of pentoxifylline (Ptx) and vitamin E (VE), which has reduced lung damage in breast cancer patients (5) (6). The addition of Ptx and VE in retreatment of NSCLC may similarly reduce radiation-induced pneumonitis. The purpose of this study is to prospectively evaluate the efficacy of Ptx and VE in reducing grade 3 pneumonitis in patients undergoing SABR with loco-regionally recurrent lung cancer or new lung primary tumors in the setting of prior thoracic radiation. We hypothesize that these patients will experience rates of grade 3 pneumonitis lower than 30% at 3, 6, and 12-months post-treatment follow up.

MATERIALS/METHODS

Patients who received radiation for a prior thoracic malignancy with a diagnosis of a recurrent or new NSCLC were recruited from our institution. Ptx and VE were administered at the time of simulation, approximately 1 week prior to starting treatment and continued for 12 weeks after the completion of treatment. SABR was delivered using standard stereotactic techniques to a dose of 5000 cGy at 1000 cGy per fraction over 2 weeks. The following demographic information was collected: baseline performance status, time interval between initial radiation and retreatment radiation, central or peripheral recurrent tumor, and pre-treatment FEV1. Patients were assessed clinically and radiographically for grades of pneumonitis at 3, 6, and 12-months post treatment.

RESULTS

Demographic and follow-up data were collected from the initial cohort of 40 patients. There were no statistically significant correlations between pretreatment characteristics and pneumonitis. 92% of participants were medication compliant. Crude rates of pneumonitis at any time point were grade 1 (23%), grade 2 (10%), and grade 3 (2%). Only one of our patients experienced grade 3 pneumonitis. The rate of grade 3 pneumonitis in our Ptx and vitamin E treated cohort was significantly less than 30% at 3-months (p = 0.001), 6-months (p = 0.001), and 12-months (p = 0.014) post-treatment.

CONCLUSION

Thus, we conclude that Ptx and VE are safe interventions that may prophylactically reduce rates of grade 3 pneumonitis for patients receiving subsequent SABR for recurrent NSCLC. Additional studies should be performed to evaluate the use in of Ptx and VE in the retreatment setting.

The association of hypertension, hypertension duration, and control with incident heart failure in black and white adults

Associations between hypertension and some cardiovascular diseases are stronger in black vs white adults. We examined associations of hypertension, hypertension duration, and control with incident heart failure (HF) in black and white REasons for Geographic And Racial Differences in Stroke study participants (n = 25 770) who were followed for incident HF hospitalization (n = 947) from enrollment in 2003-2007 through 2015. Hypertension was defined, using updated US guidelines, as systolic or diastolic blood pressure (BP) ≥130/80 mm Hg or antihypertensive medication use. Duration was assessed at baseline, and control was defined as treated BP < 130/80 mm Hg. Compared with no hypertension, hypertension was associated with higher risk of incident HF (HRwhites 1.90 [95% CI 1.49, 2.41], HRblacks 2.36 [95% CI 1.53, 3.65]), HF with preserved ejection fraction (HRwhites 2.01 [95% CI 1.34, 3.01], HRblacks 2.70 [95% CI 1.25, 2.53]), and HF with reduced/mid-range ejection fraction (HRwhites 1.69 [95% CI 1.23, 2.33], HRblacks 2.29 [95% CI 1.26, 4.15]). Hypertension duration <10 years and ≥10 years were associated with higher risk for incident HF compared with no hypertension. Although risk of incident HF was highest among participants with uncontrolled BP, even controlled BP vs no hypertension was associated with increased risk of HF (HRwhites 1.93 [95% CI 1.44, 2.58], HRblacks 2.01 [95% CI 1.22, 3.29]). Interactions with race were not statistically significant. The risk of HF associated with hypertension, even with shorter duration or controlled BP, suggests that both prevention and therapeutic management of hypertension are important in reducing HF risk.

Long-term molecular analysis of tuberculosis strains in alabama, a state characterized by a largely indigenous, low-risk population

With a tuberculosis case detection rate of 5.9 per 100,000 population in 2001, Alabama ranked twelfth highest in the United States. However, cases among foreign-born and human immunodeficiency virus-infected individuals remain low in Alabama. To understand the endemic statewide disease pattern, tuberculosis strains were studied for clustering in a long-term population-based study from January 1994 to May 2000. IS6110 restriction fragment length polymorphism analysis was performed for 1,834 strains. Spoligotyping was used as a secondary typing method for the 37% of isolates displaying a restriction fragment length polymorphism pattern with <6 IS6110 copies. A total of 721 (41%) patients provided isolates that composed 114 clusters, each containing isolates from 2 to 136 patients, suggesting that recent transmission accounted for 35% of tuberculosis cases. Demographic, behavioral, and clinical characteristics of patients with clustered versus nonclustered isolates stratified by low-copy-number strains (<6 IS6110 copies) versus high-copy-number strains (> or =6 IS6110 copies) were evaluated. Younger age, black race, a history of alcohol abuse, and homelessness were predictors of clustering of low-copy-number, strains and younger age, urban residency, alcohol abuse, homelessness, noninjection drug use, and a history of incarceration and/or cavitary disease were predictors of clustering of high-copy-number strains. By identifying local characteristics of tuberculosis clustering through molecular fingerprinting, control programs can distribute their limited resources to impact the transmission of tuberculosis in high-risk populations and evaluate strain distribution across geographical areas.

Molecular typing of Mycobacterium tuberculosis strains with a common two-band IS6110 pattern

We conducted a program of population-based molecular typing of all Mycobacterium tuberculosis isolates obtained in Alabama since 1994. Of 2452 isolates, 1013 (41%) had fewer than 6 bands of IS6110; 348 (14%) had a single two-band pattern (JH2). With conventional epidemiologic methods, we identified three groups of related patients with JH2 isolates. Spoligotyping and pattern of variable number of tandem repeats identified 10 molecular groups; two found by conventional methods were subdivided.

Molecular differentiation of Mycobacterium tuberculosis strains without IS6110 insertions

By using standard restriction fragment length polymorphism, 6 zero-copy IS6110 Mycobacterium tuberculosis isolates were identified from 1180 Maryland isolates as part of the National Tuberculosis Genotyping and Surveillance Network Project. By using various genotyping methods, we demonstrated that this zero band cluster can be differentiated into six genotypes.

Expression, autoregulation, and DNA binding properties of the Mycobacterium tuberculosis TrcR response regulator

The TrcRS two-component system of Mycobacterium tuberculosis is comprised of the TrcS histidine kinase and the TrcR response regulator, which is homologous to the OmpR class of DNA binding response regulators. Reverse transcription-PCRs with total RNA showed that the trcR and trcS two-component system genes are transcribed in broth-grown M. tuberculosis. Analysis of the trcR and trcS genes using various SCOTS (selective capture of transcribed sequences) probes also confirmed that these genes are expressed in broth-grown cultures and after 18 h of M. tuberculosis growth in cultured human primary macrophages. To determine if the TrcR response regulator is autoregulated, a trcR-lacZ fusion plasmid and a TrcR expression plasmid were cotransformed into Escherichia coli. Upon induction of the TrcR protein, there was a >500-fold increase in beta-galactosidase activity from the trcR-lacZ fusion, indicating that TrcR is involved in transcriptional autoactivation. Gel mobility shift assays with the trcR promoter and TrcR established that the response regulator was autoregulating via direct binding. By use of a delimiting series of overlapping trcR PCR fragments in gel mobility shift assays with TrcR, an AT-rich region of the trcR promoter was shown to be essential for TrcR binding. Additionally, this AT-rich sequence was protected by TrcR in DNase I protection assays. To further analyze the role of the AT-rich region in TrcR autoregulation, the trcR promoter was mutated and analyzed in lacZ transcriptional fusions in the presence of TrcR. Alteration of the AT-rich sequence in the trcR promoter resulted in the loss of trcR transcriptional activation in the presence of TrcR. This report indicates that the M. tuberculosis TrcR response regulator activates its own expression by interacting with the AT-rich sequence of the trcR promoter.

Predictive model to identify positive tuberculosis skin test results during contact investigations

CONTEXT

Budgetary constraints in tuberculosis (TB) control programs require streamlining contact investigations without sacrificing disease control.

OBJECTIVE

To develop more efficient methods of TB contact investigation by creating a model of TB transmission using variables that best predict a positive tuberculin skin test among contacts of an active TB case.

DESIGN, SETTING, AND SUBJECTS

After standardizing the interview and documentation process, data were collected on 292 consecutive TB cases and their 2941 contacts identified by the Alabama Department of Public Health between January and October 1998. Generalized estimating equations were used to create a model for predicting positive skin test results in contacts of active TB cases. The model was then validated using data from a prospective cohort of 366 new TB cases and their 3162 contacts identified between October 1998 and April 2000.

MAIN OUTCOME MEASURE

Tuberculin skin test result.

RESULTS

Using generalized estimating equations to build a predictive model, 7 variables were found to significantly predict a positive tuberculin skin test result among contacts of an active TB case. Further testing showed this model to have a sensitivity, specificity, and positive predictive value of approximately 89%, 36%, and 26%, respectively. The false-negative rate was less than 10%, and about 40% of the contact workload could be eliminated using this model.

CONCLUSIONS

Certain characteristics can be used to predict contacts most likely to have a positive tuberculin skin test result. Use of such models can significantly reduce the number of contacts that public health officials need to investigate while still maintaining excellent disease control.

Value of Mycobacterium tuberculosis fingerprinting as a tool in a rural state surveillance program

OBJECTIVE

This study demonstrates the value of Mycobacterium tuberculosis fingerprinting used in conjunction with traditional epidemiologic methods to identify smoldering outbreaks of tuberculosis in endemic areas where background rates of tuberculosis are high.

METHODS

IS6110 DNA fingerprinting was performed on isolates of M tuberculosis from verified cases of tuberculosis in Alabama from 1994 to 1998. A statewide database groups isolates into "clusters" and tracks them cumulatively over time. A large cluster was identified and was secondarily investigated using traditional epidemiologic methods.

RESULTS

Twenty-five isolates were found to be identical by fingerprinting analysis. Patients were living within 10 counties across the state, and 12 cases were localized to a single county. This represented an ongoing, statewide tuberculosis outbreak previously unrecognized by local and state health officials. Secondary investigation of the cases revealed the primary sites of transmission to be a correctional facility and two homeless shelters.

CONCLUSIONS

Population surveillance using M tuberculosis fingerprinting was successfully utilized to detect a significant and smoldering tuberculosis outbreak. Measures are currently in place to identify and prevent further transmission in the involved locations.

Identification of a contaminating Mycobacterium tuberculosis strain with a transposition of an IS6110 insertion element resulting in an altered spoligotype

Molecular fingerprinting with the IS6110 insertion sequence is useful for tracking transmission of Mycobacterium tuberculosis within a population or confirming specimen contamination in the laboratory or through instrumentation. Secondary typing with other molecular methods yields additional information as to the relatedness of strains with similar IS6110 fingerprints. Isolated, relatively rare, random events within the M. tuberculosis genome alter molecular fingerprinting patterns with any of the methods; therefore, strains which are different by two or more typing methods are usually not considered to be closely related. In this report, we describe two strains of M. tuberculosis, obtained from the same bronchoscope 2 days apart, that demonstrated unique molecular fingerprinting patterns by two different typing methods. They were closely linked through the bronchoscope by a traditional epidemiologic investigation. Genetic analysis of the two strains revealed that a single event, the transposition of an IS6110 insertion sequence in one of the strains, accounted for both the differences in the IS6110 pattern and the apparent deletion of a spacer in the spoligotype. This finding shows that a single event can change the molecular fingerprint of a strain in two different molecular typing systems, and thus, molecular typing cannot be the only means used to track transmission of this organism through a population. Traditional epidemiologic techniques are a necessary complement to molecular fingerprinting so that radical changes within the fingerprint pattern can be identified.

Preventable childhood tuberculosis in Alabama: implications and opportunity

Childhood tuberculosis (TB) cases indicate recent community transmission and thus reflect the effectiveness of TB control efforts, particularly the contact investigation.

OBJECTIVE

To evaluate all preventable childhood TB cases and implications in the context of TB morbidity trends.

DESIGN

Statewide morbidity trends are presented from 1983 to 1997. Since 1992, each child TB case is classified as either preventable or not preventable, based on a standard definition.

MAIN OUTCOME MEASURES

Case characteristics (preventable and not preventable), TB disease rates over time, and reasons for preventable case classification.

SETTING

Alabama TB control program, from January 1, 1983 through December 31, 1997.

RESULTS

For the period 1983-1997, nonwhite children had a higher disease rate (rate ratio: 5.7; 95% confidence interval: 4.3,7.6) than white children. Since 1990, the overall child rate has increased significantly despite a decline in the adult rate. Among 120 child cases diagnosed from 1992 to 1997, 25 (21%) were classified as preventable. The causes were contact investigation interview failure (12/25 = 48%), delay to evaluation (16%), source case noncompliance with previously prescribed preventive therapy (16%), and source case diagnosed out of state (16%) with no initial investigation performed in Alabama. All preventable cases identified were black children; the proportion of preventable cases did not vary by age group or sex. During 1996, the case rate for nonwhite children exceeded that of adult whites.

CONCLUSIONS

Childhood TB in Alabama for nonwhites is rising despite a national downward trend. TB is clearly a disproportionate disease burden for the state's African American population, and the median case age is falling. Additional research and improved training in contact investigation are required to assess this situation and effectively intervene.

Spot sputum screening: evaluation of an intervention in two homeless shelters

SETTING

Two homeless shelters in Birmingham, Alabama.

OBJECTIVE

To interrupt tuberculosis transmission and evaluate the utility of spot sputum screening.

DESIGN

Two shelters participated in the study between May 1996 and February 1997. A spot sputum specimen was collected on a given evening from each overnight client. Information was obtained regarding symptoms and tuberculin skin test (TST) status. There were four screenings during two rounds, with TST in round one only.

RESULTS

Of 127 persons involved in the study, 120 (95%) provided specimens, and four tuberculosis cases were identified (4/127, 3.1%). Symptoms were infrequently reported. RFLP analysis (IS6110) confirmed a two-band cluster in three of the four cases; another matching two-band strain was found in a drug rehabilitation client staying in one shelter. Secondary RFLP typing (pTBN12) confirmed the homeless cluster. Costs were $1311 per case identified. Among 92 clients with a prior TST, 40% reported a positive result (37/92). Of 21 PPD tests read, 11 were > or =10 mm (52%).

CONCLUSION

Spot sputum screening is effective in identifying unsuspected tuberculosis cases in shelters. It has acceptable costs, is logistically simple and efficient. Symptom screening was not useful in this general homeless population. RFLP analysis showed cloning of the two-band strain. Given the evidence for ongoing transmission, sputum screening should be considered in shelter settings.

In vitro evidence of two-component system phosphorylation between the Mycobacterium tuberculosis TrcR/TrcS proteins

Two-component regulatory proteins, histidine kinases and response regulators, function in bacteria as sensing and adaptive factors in response to a wide range of environmental stimuli. Conserved histidine and glycine regions of histidine kinase sensor proteins were used to design degenerate oligonucleotide primers for amplification of DNA fragments from Mycobacterium tuberculosis. Two adjacent genes, trcR and trcS, which encode a response regulator and a histidine kinase, respectively, have been identified. Full-length and truncated TrcR and TrcS proteins have been expressed in Escherichia coli. Difficulties in expressing recombinant full-length TrcS and a truncated N -terminal form of TrcS reveal that the transmembrane domains are toxic to E. coli. Overexpressed truncated C-terminal transmitter domains of TrcS have been autophosphorylated in vitro and have transphosphorylated both the full-length recombinant TrcR protein and the N -terminal receiver/regulator domain of TrcR. In vitro autophosphorylation of TrcS requires the presence of Mn2+or Ca2+as a divalent cation cofactor and subsequent transphosphorylation of TrcR is evident in the presence of TrcS-phosphate and Ca2+. Transphosphorylation between these two proteins provides evidence that these M. tuberculosis genes encode functional two-component system regulatory proteins that are members of a signal transduction circuit.

Restriction fragment length polymorphism screening of Mycobacterium tuberculosis isolates: population surveillance for targeting disease transmission in a community

SETTING

Alabama State Tuberculosis Control Program, USA.

OBJECTIVE

To combine molecular screening data with routine information to assess transmission of Mycobacterium tuberculosis and improve control efforts.

DESIGN

Since January 1994, samples from tuberculosis cases statewide have been systematically analyzed by IS6110 restriction fragment length polymorphism (RFLP). All cases during 1994-1995 with a predominate RFLP pattern were evaluated and risk factors assessed. pTBN12 was used to evaluate a large cluster in the Birmingham-Jefferson County (BJC) area.

RESULTS

Statewide, a common two-band pattern was found, named JH2 (99/566, 17.5%). The most important risk associated with this pattern was homelessness (odds ratio, 8.9; P < 0.001). In the BJC area, the homeless accounted for 29% (51/175) of new cases diagnosed during the study period. For the BJC homeless, there were 13 unique RFLP patterns, and JH2 was predominant (29/33, 88%) among three clusters. Secondary analysis of the homeless JH2 cluster revealed a large group that included 19 of 24 (79%) isolates analyzed. Compared with the BJC non homeless (n = 124), the homeless were younger (P < 0.001), of male gender (P < 0.001), black race (P = 0.002), and were heavy alcohol (P < 0.001) and non-injection drug (P = 0.001) users.

CONCLUSIONS

By screening tuberculosis cases statewide, a common two-band RFLP pattern was identified. Its predominance is explained by an ongoing tuberculosis epidemic among Birmingham's homeless population, highlighting RFLP as a tool for population surveillance. The pattern differences observed by pTBN12 typing clearly demonstrate that the isolates might be related but are not clonal.

Low serum antimycobacterial drug levels in non-HIV-infected tuberculosis patients

BACKGROUND

Despite the use of directly observed therapy (DOT) by tuberculosis control programs, patient treatment failure, relapse, and acquired drug resistance remain problematic in a small number. We investigated serum drug levels in non-HIV-infected tuberculosis patients who were receiving DOT by the health department and did not respond to treatment as expected.

METHODS

The indications for checking levels were as follows: (1) slow clinical response or failure to convert the sputum culture within 12 weeks; (2) treatment failure, early disease relapse < 13 months since being declared cured; (3) relapse, late disease reactivation > or = 13 months since being declared cured; and (4) acquired drug resistance while receiving DOT. Baseline characteristics of control subjects who responded to therapy as expected were compared. Venous blood for analysis was obtained at 2 h after directly observed ingestion and measured by high-performance liquid chromatography.

RESULTS

Twenty-four patients receiving daily or twice-weekly standard therapy with isoniazid (INH, 300 or 900 mg) and rifampin (RMP, 600 mg) were identified; 22 had drug levels evaluated at 2 h. For INH, 15 of 22 patients (68%) had levels less than the reported target range. For RMP, 14 of 22 patients (64%) had low levels. Among the 14 patients receiving INH, 900 mg, and RMP, 600 mg, 4 (29%) had very low levels of both. Use of a combination INH/RMP tablet was associated with lower INH levels (p=0.04); however, RMP levels were higher (p<0.02). Alcohol use was associated with significantly higher RMP (p<0.01) serum concentrations.

CONCLUSIONS

Important questions remain concerning the utility and timing of serum drug measurements. However, if a patient is not responding to therapy as expected and one is assured that the Mycobacterium tuberculosis organism is susceptible to the drugs given and that the patient is taking the medication as prescribed, drug level monitoring should be considered.

Early bactericidal activity of isoniazid in pulmonary tuberculosis. Optimization of methodology. The DATRI 008 Study Group

Early bactericidal activity (EBA) of antituberculosis drugs is the rate of decrease in the concentration of tubercle bacilli sputum during the initial days of therapy. The study reported here was designed to optimize the methodology for obtaining precise EBA measurements. The study compared the results with two versus five treatment days; overnight sputum collections with early morning collections; and quantitative smears for acid-fast bacilli (AFB) with quantitative cultures. Isoniazid (INH) was used as a model drug. Among 28 smear-positive patients enrolled in the study in five cities in the United States, 16 were evaluable (INH-susceptible tuberculosis [TB] and adequate sputum collections). The mean baseline bacterial load was 6.69 log10 cfu/ml (SE = 0.24). Quantitative culture of 10- or 12-h sputum collections obtained on two baseline days and treatment Day 5 was the optimal method for EBA measurement. The mean 5-d EBA was 0.21 log10 cfu/ml/d (SE = 0.03; p < 0.001) and the EBA appeared to be constant during the first five treatment days. On the basis of these data, multiarm studies of investigational drugs will require 25 evaluable subjects per arm to detect (80% power and two-tailed alpha of 0.05) an EBA at least 50% as large as the EBA of INH. In countries with a low incidence of TB, the usefulness of this methodology for rapidly assessing new antituberculosis agents may be limited by the relatively large number of subjects required to compare EBA values across treatment arms.

Transmission of Mycobacterium tuberculosis to recipients of single lung transplants from the same donor

Recipients of organ transplants are at increased risk for infection both because of immunosuppression and because of the transfer of microbes through the donor organs. We report two cases of M. tuberculosis disease in recipients of single lung transplants who shared a common donor. Both recipients developed pulmonary tuberculosis, one having fever and pulmonary infiltrates and the other having subclinical disease with M. tuberculosis organisms being recovered from bronchoalveolar lavage. Restriction fragment length polymorphism analysis on both isolates of M. tuberculosis revealed a common source. The donor of both lungs had a normal chest radiograph and no known prior history of M. tuberculosis infection of disease. These cases are the first report of two single lung recipients developing pulmonary tuberculosis from a common donor.

Laboratory contamination of Mycobacterium tuberculosis cultures

The purpose of this study was to investigate possible laboratory contamination of Mycobacterium tuberculosis cultures which resulted in the misdiagnosis of tuberculosis. We have investigated three cases in which a patient's culture was positive for M. tuberculosis but there was not a high clinical suspicion for disease. In each instance, another patient with clinically obvious pulmonary tuberculosis had specimens cultured concurrently within the same clinical laboratory. The isolates from both the obvious cases of tuberculosis and the suspect cases were obtained through the State of Alabama TB Laboratory, but these isolates originated at a commercial laboratory, a community hospital laboratory, and at a university hospital. MTB isolates were fingerprinted by probing for the insertion sequence IS6110. With each of the three pairs of isolates (case and suspicious case), identical IS6110 banding patterns were found suggesting identical MTB strains. Because the patients were geographically separated, it is strongly suspected that laboratory contamination of M. tuberculosis cultures resulted in the three suspect cases being diagnosed with tuberculosis. These findings indicate that positive M. tuberculosis cultures resulting from laboratory contamination can occur.

Childhood tuberculosis in Alabama: epidemiology of disease and indicators of program effectiveness, 1983 to 1993

An 11-year review of childhood tuberculosis in Alabama was made in order to define indicators of program effectiveness in interrupting community transmission. Minority (nonwhite) children, 96% of whom were black, had the highest risk of disease (odds ratio, 5.5; 95% confidence interval, 3.9, 7.7). Of 171 cases, 71% (n = 122) occurred in blacks and 2% (n = 3) occurred in Asian-Pacific islanders. Age 0 to 4 years (107 of 171) compared with age 5 to 14 years (64 of 171) was an additional risk factor for the development of tuberculosis (odds ratio, 3.4; 95% confidence interval 2.5, 4.7)), whereas gender was not. Males accounted for 49% of cases (83 of 171). During the period 1983 to 1993 there was no trend of increasing or decreasing numbers among child cases (trend test P = 0.94) despite significant changes by year. The purified protein derivative test had a 9% (8 of 89) false negative rate and was significantly more likely to be negative in children younger than 1 year (4 of 12 vs. 4 of 77; P = 0.01). During the 2-year interval 1992 to 1993, 19% of cases were thought to be preventable. We believe that the PPD skin test is useful and an improved contact investigation is essential to preventing childhood tuberculosis. Miniepidemics of transmission of tuberculosis from adults to a large group of children partially explain the observed disease pattern.

Drug-resistant tuberculosis in adults: implications for the health care worker

In recent years, several outbreaks of drug-resistant tuberculosis have occurred in U.S. hospitals. In response to this recognized risk of tuberculosis exposure in health care facilities, the Centers for Disease Control and the Occupational Safety and Health Administration have issued guidelines or policy procedures for minimizing risks of tuberculosis transmission within these facilities. Some of the recommendations outlined in these governmental documents have been controversial. In this review the guidelines/policies and the debate surrounding them are discussed as they affect the health care worker who cares for adult patients with tuberculosis.

Immunology of tuberculosis

TB is a chronic, necrotizing infection caused by M. tuberculosis. The clinical manifestations of disease are the result of a balance between the host response and bacterial virulence. Cellular immunity is responsible for effective control of infection, but cytokines released during the process of cellular immunity may also cause harm to the host. Humoral immunity plays little part in protection against TB. Individuals with defective cellular immunity are much more susceptible to disease from M. tuberculosis and are more likely to have a disseminated form of TB.

The use of monozygotic and dizygotic twins to estimate the effects of inheritance on the levels of immunoglobulin isotypes and antibodies to phosphocholine

In the elderly there is a pronounced increase in susceptibility to infectious disease. Evidence for particular immune deficits that result in susceptibility to specific agents is lacking, however, and there is little information on the degree to which differences in the susceptibility among the elderly are due to genetic versus environmental effects. A strong association has been observed between eventual fatal pneumonia and elevated levels of IgM antibody to phosphocholine (PC) levels at age 70. In this study we evaluated the heritability of IgM and IgG antibody levels to phosphocholine in the elderly using monozygotic and dizygotic male twins. We observed genetic regulation of serum levels of IgM antibody to PC, a finding which suggests that susceptibility of the elderly to fatal pneumonia may be heritable. Levels of total IgM were under separate genetic control and there was no genetic effect on IgG and IgA levels or levels of IgG antibody to phosphocholine.

A 'safe-site' for Salmonella typhimurium is within splenic polymorphonuclear cells

Following oral or systemic infection with Salmonella typhimurium, the focus of infection is in the liver and spleen. The majority of Salmonella surviving in the liver and spleen by 4 h post infection are already in an environment where they are largely protected from subsequent killing. Previous studies have shown that the majority of surviving Salmonella are intracellular. In the present study we sought to determine the cell type containing most of the cell-associated Salmonella liberated from the spleen. We enriched for Salmonella-containing cells by Ficoll-Hypaque separation followed by fluorescence-activated cell sorting. Approximately 85% of the total intracellular Salmonella were found in Mac-1+/J-11d+ cell fractions of the Ficoll-Hypaque band and pellet. By microscopic examination of stained cells from the sorted cell populations, it was evident that virtually all of the Salmonella were in polymorphonuclear cells (PMN). The numbers of Salmonella observed microscopically were similar in numbers to Salmonella colony forming units detected by plating. Salmonella containing PMN in the Ficoll band generally contained a single bacterium, while those from the probably less healthy cells in the Ficoll pellet generally contained several Salmonella.

T helper/inducer (CD4+) cells prestimulated with PPD induce monocytes to produce interleukin-1 beta

We obtained peripheral blood mononuclear cells (PBMC) from four healthy, tuberculin purified protein derivative (PPD) reactive donors and cultured these cells in media containing PPD (low dose = 200 ng/ml or high dose = 1 micrograms/ml). Five days after the addition of PPD, T cells were isolated, washed, and added to autologous adherent cell cultures at a 1:1 ratio. Adherent cells were then cultured for 24 h in media only (baseline), media plus lipopolysaccharide (LPS, 2 micrograms/ml; positive control), or media containing the prestimulated T cells. After 24 h, supernatants were harvested and interleukin 1 beta (IL-beta) levels were assayed by radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). The results show that T cells prestimulated with low dose PPD (200 micrograms/ml) did not induce IL-1 production by adherent cells (mean increase over baseline 0.2 +/- 1.3 standard deviation [SD] ng/ml, P = 0.61). However, T cells prestimulated with high dose PPD (1 microgram/ml) did induce adherent cells to secrete IL-1 beta (mean increase over baseline 1.7 +/- 0.62 [SD] ng/ml, P = 0.01), but this induction was abolished when cell-to-cell contact was prevented by use of double well chambers (mean increase over baseline 0.1 +/- 0.36 [SD] ng/ml, P = 0.69). Prestimulated T helper (CD4+) cells were able to induce monocytes to secrete IL-1 beta but prestimulated CD8+ T cells were not. These data suggest that when T helper (CD4+) cells are sufficiently activated they acquire the ability to induce monocytes to secrete IL-1 beta. Cell-to-cell contact between monocytes and T cells is required. This function of activated T cells may be important in the normal cellular immune response.

A 'safe-site' for Salmonella typhimurium is within splenic cells during the early phase of infection in mice

Salmonella typhimurium infection in mice is focused on the spleen and liver, and prolonged infection can lead to sepsis and death. After intravenous infection with a moderate dose of S. typhimurium, the few bacteria that survive in the spleen and liver grow in a 'safe-site' where they are protected from immune destruction. In this study, we demonstrated that the lack of killing of resident salmonella in the spleen and liver was not because the salmonella were transformed within the host and became resistant to killing, or because the infected mice lost the ability to kill salmonella. We showed that the salmonella were within an intracellular 'safe-site' that protected them from killing. Brief treatment of salmonella-infected mice with gentamicin reduced the numbers of salmonella in the blood but had no effect on the numbers in the liver and spleen, suggesting an intracellular location of the salmonella. After dissociation of spleen cells from recently infected mice, 60% of the salmonella remained cell associated. These cell-associated salmonella, unlike cell-free salmonella, were resistant to killing by gentamicin. The cell-associated salmonella were rendered susceptible to gentamicin after sonication, providing confirmation of their previous intracellular location.

In vitro natural killer and lymphokine-activated killer activity in patients with bronchogenic carcinoma

The authors examined peripheral blood mononuclear cells from 45 patients with bronchogenic carcinoma to determine natural killer (NK) and lymphokine-activated killer (LAK) activity after in vitro incubation with media alone or media plus interferon gamma (IFN, 200 U/ml) and/or interleukin-2 (IL-2, 100 U/ml). Our results show that lymphocytes from patients with bronchogenic carcinoma can acquire LAK activity, but the level of activity acquired was significantly lower compared with lymphocytes from 25 control subjects when IL-2 cultures were supplemented with 10% autologous human serum (AHS) (15.6% +/- 2.1% specific release versus 26.0% +/- 2.9% specific release, P = 0.004). The LAK activity, defined as cytotoxicity of an NK-resistant cell line, of the patients' lymphocytes was augmented when cells were cultured with both IL-2 and IFN compared with IL-2 alone (P = 0.0001, paired t-test). Control subjects were unchanged (P = 0.09). There was no significant difference between groups of patients with different histologic types of tumor or different stages of disease. The NK activity, defined as killing of NK-sensitive K-562 target cells, of the patients' lymphocytes was not significantly different from that of the controls' lymphocytes (42.8% +/- 3.0% specific release versus 49.3% +/- 3.3% specific release, P = 0.16). These studies indicate the feasibility of IL-2 and IFN therapy in patients with bronchogenic carcinoma.

Corticosteroids in asthma

The use of corticosteroids in the treatment of asthma has significantly decreased the morbidity and mortality from this disease. However, corticosteroids have devastating side effects when given frequently or for prolonged periods. High doses of systemic corticosteroid preparations should be used only during bouts of acute bronchospasm, whereas the lowest possible dose needed to control symptoms is recommended for the treatment of chronic asthma. Aerosolized steroids offer an alternative to systemic preparations and have less associated morbidity. Various corticosteroid preparations have various potencies and durations of action that need to be considered. Patients with coexisting liver disease require preparations that do not need hepatic hydroxylation, whereas patients with congestive heart failure require preparations that minimize salt retention. When asthma and pregnancy coexist, it is vital that symptoms of bronchospasm are controlled to protect the fetus. During stressful situations, such as surgery, it is important to consider the possibility of hypothalamic-pituitary-adrenal axis suppression if the asthmatic patient has been previously treated with corticosteroids.

Human B cell differentiation by Fc fragment. III. Effect of IL-1 and IL-2 on differentiation of human B lymphocytes induced by Fc fragments of human IgG

The human Fc fragment of IgG, when added to blood mononuclear cells in vitro, induces B cell differentiation after 6 days of culture. This activity requires the presence of T cells and monocytes. This work explores the roles of interleukin 1 (IL-1) and interleukin 2 (IL-2) in B cell differentiation induced by Fc fragments. Peripheral blood mononuclear cells (PBMC) from normal donors were examined for plasma cell differentiation following stimulation with Fc fragment (15 and 30 micrograms/ml) with or without IL-1 (6 U/ml) or IL-2 (2 U/ml). Results indicate that both IL-1 and IL-2 accelerated B cell differentiation by the Fc fragment to 3 days of culture, compared to 6 days required with the Fc fragment alone. The time required for differentiation was not further shortened when both IL-1 and IL-2 were present in culture; both IL-1 and IL-2 were able to partially induce B differentiation alone at 6 days of culture. The importance of IL-2 in B cell differentiation was further supported by the finding that antibodies specific for the IL-2 receptor blocked B cell differentiation induced by Fc fragments, with or without additional IL-1 or IL-2. The depletion of monocytes also blocked B cell differentiation and the requirement for monocytes could not be replaced by exogenous IL-1; however, Fc fragments were shown to induce monocytes to secrete IL-1 beta after 24 hr in culture. These results suggest that accelerated differentiation of B cells into plasma cells requires a double signal provided by Fc fragments and IL-1 or IL-2. Monocytes are necessary for Fc fragment-induced differentiation and cannot be replaced by either IL-1 or IL-2.

Interleukin-2 augmentation of interleukin-1 and prostaglandin E2 production

Some of the major side effects of interleukin-2 (IL-2) therapy in the treatment of malignancies may be related to increased interleukin-1 (IL-1) and/or prostaglandin E2 (PGE2) production. We examined the effect of recombinant (rIL-2) on the in vitro production of IL-1 beta and PGE2 by unstimulated and LPS-activated human blood mononuclear cells (PBMC). We also compared the effect of rIL-2 on IL-1 beta production by adherent and nonadherent blood mononuclear cell populations. Cultures of PBMC (5 x 10(6)/ml) were incubated for 24 hr in media only (control, 1,000 U/ml rIL-2, 2 micrograms/ml LPS, or both LPS and rIL-2. Supernatants obtained from these cultures were analyzed for levels of IL-1 beta and PGE2 by radioimmunoassays. The addition of rIL-2 caused an increase in IL-1 beta production in 13 of 13 control PBMC cultures and in 11 of 13 LPS-stimulated cultures, which were significant increases as determined by paired t tests. When PBMC were fractionated into plastic adherent and nonadherent populations, the rIL-2 induced increases in IL-1 beta production were more consistent in control (six of seven cases) and LPS (seven of seven cases) cultures of plastic nonadherent cells than in control (three of seven cases) and LPS (four of seven cases) cultures of plastic adherent cells. Recombinant IL-2 did not increase PGE2 production in control PBMC cultures (none of four cases), but did so in LPS-stimulated PBMC cultures (three of four cases]. These results suggest that rIL-2 may increase IL-1 production in vivo and thus possibly account for some of the side effects of this therapy.

Expression of myelomonocytic antigens on chronic lymphocytic leukemia B cells correlates with their ability to produce interleukin 1

We analyzed the expression of myelomonocytic-associated antigens on lymphocytes from B cell chronic lymphocytic leukemia (B-CLL) patients. Blood mononuclear cells were depleted of monocytes by one-step Percoll density gradient centrifugation and tested for antigen expression by fluorescent microscopy and flow cytometry. The reactivity of patient lymphocytes was as follows: 26 of 31 were positive for CD14 (Myr), 22 of 31 for a monocyte Fc receptor (MFC-1), 22 of 31 for CD11b (C3bi receptor), eight of 31 for CD15 (Leu-M1), five of 18 for CD13 (My 7), seven of 18 for My 9, and five of 30 for Mo 2. The B lymphocytes of B-CLL patients were also tested for the ability to produce interleukin 1 (IL-1) after depletion of monocytes and T lymphocytes. In 13 of 17 cases, B lymphocytes of patients produced IL-1 as detected in a mouse thymocyte proliferation assay and, in selected cases, a radioimmunoassay specific for IL-1 beta. The 13 cases that produced IL-1 were also positive for the expression of one or more myelomonocytic-associated antigens, whereas the four cases that did not produce IL-1 lacked expression of these antigens. In conclusion, the malignant B cells of B-CLL patients frequently express a variety of antigens generally considered specific for myelomonocytic cells, and expression of these antigens is associated with the ability to produce IL-1.

Analysis of the monocyte Fc receptors and antibody-mediated cellular interactions required for the induction of T cell proliferation by anti-T3 antibodies

The induction of human T cell proliferation by antibodies that cross-link T3 antigens is dependent on functional interactions of anti-T3 antibodies with monocyte Fc receptors. In this report, we used a panel of anti-T3 antibodies of differing heavy chain isotype and a variety of other monoclonal antibodies to analyze several features of the antibody-mediated interactions between T cells and monocytes that are required for mitogenesis. Whereas three IgG2a anti-T3 antibodies were mitogenic for cells from all individuals, IgM and IgG2b anti-T3 antibodies did not induce T cell proliferation in any donor and could block the proliferative responses induced by other mitogenic anti-T3 antibodies. Dose-response analyses with four IgG1 anti-T3 antibodies demonstrated donor heterogeneity as reported by other investigators. However, in contrast to these previous reports, high concentrations of IgG1 anti-T3 antibodies were found to be mitogenic for all donors, indicating that this heterogeneity is based on relative rather than absolute defects in low responder monocytes. Cell mixing experiments in which monocytes from two different low responder donors were co-cultured with T cells and IgG1 anti-T3 antibodies did not identify any complementary defects, suggesting that the low responder phenotype results from a relatively restricted polymorphism. To assess the nature of the signals required for inducing T cell proliferation, nonmitogenic anti-T3 antibodies were co-cultured with other pan-T cell antibodies having the IgG2a isotype. The combination of signals from T3 antigen cross-linkage and those independently generated by other IgG2a antibodies bound to monocyte Fc receptors did not induce T cell proliferation. Hence, it appears that the T3 antigen or closely associated structures must be clustered at the monocyte membrane for mitogenesis. Finally, in competitive inhibition experiments, the isotype specificity of monocyte Fc receptors involved in the induction of T cell proliferation was examined. Two distinct Fc receptor sites, one that binds murine IgG2a and IgG3 antibodies and a second that binds murine IgG1 antibodies, were identified. Murine IgM or IgG2b did not appear to bind either of these receptor sites. Taken together, these data indicate that human monocytes have two distinct Fc receptor sites, which must specifically and directly interact with T cell-bound anti-T3 antibodies for mitogenesis.

Analysis of the monocyte Fc receptors and antibody-mediated cellular interactions required for the induction of T cell proliferation by anti-T3 antibodies

The induction of human T cell proliferation by antibodies that cross-link T3 antigens is dependent on functional interactions of anti-T3 antibodies with monocyte Fc receptors. In this report, we used a panel of anti-T3 antibodies of differing heavy chain isotype and a variety of other monoclonal antibodies to analyze several features of the antibody-mediated interactions between T cells and monocytes that are required for mitogenesis. Whereas three IgG2a anti-T3 antibodies were mitogenic for cells from all individuals, IgM and IgG2b anti-T3 antibodies did not induce T cell proliferation in any donor and could block the proliferative responses induced by other mitogenic anti-T3 antibodies. Dose-response analyses with four IgG1 anti-T3 antibodies demonstrated donor heterogeneity as reported by other investigators. However, in contrast to these previous reports, high concentrations of IgG1 anti-T3 antibodies were found to be mitogenic for all donors, indicating that this heterogeneity is based on relative rather than absolute defects in low responder monocytes. Cell mixing experiments in which monocytes from two different low responder donors were co-cultured with T cells and IgG1 anti-T3 antibodies did not identify any complementary defects, suggesting that the low responder phenotype results from a relatively restricted polymorphism. To assess the nature of the signals required for inducing T cell proliferation, nonmitogenic anti-T3 antibodies were co-cultured with other pan-T cell antibodies having the IgG2a isotype. The combination of signals from T3 antigen cross-linkage and those independently generated by other IgG2a antibodies bound to monocyte Fc receptors did not induce T cell proliferation. Hence, it appears that the T3 antigen or closely associated structures must be clustered at the monocyte membrane for mitogenesis. Finally, in competitive inhibition experiments, the isotype specificity of monocyte Fc receptors involved in the induction of T cell proliferation was examined. Two distinct Fc receptor sites, one that binds murine IgG2a and IgG3 antibodies and a second that binds murine IgG1 antibodies, were identified. Murine IgM or IgG2b did not appear to bind either of these receptor sites. Taken together, these data indicate that human monocytes have two distinct Fc receptor sites, which must specifically and directly interact with T cell-bound anti-T3 antibodies for mitogenesis.

Cushing's syndrome. Screening methods in hospitalized patients

We studied 18 patients with Cushing's syndrome and 25 patients in which Cushing's syndrome was excluded on follow-up to evaluate screening tests for Cushing's syndrome in hospitalized patients. Plasma cortisol values (at 8 AM) were found least helpful yielding 29% false-positive and 60% false-negative values. Diurnal variation of cortisol was present in 30% of patients with Cushing's syndrome and absent in 18% of patients without Cushing's syndrome. When corrected for total urinary creatinine, 24-hour urinary 17-hydroxycorticosteroids were specific (all patients without Cushing's syndrome had normal values) but not very sensitive (two of 12 patients with Cushing's syndrome had normal values). Similarly, 24-hour 17-ketosteroids were of little help with 17% false-positive and 35% false-negative values. Twenty-four-hour urinary free cortisol was both a sensitive and specific screening test for Cushing's syndrome (no false-positive and no false-negative results). We conclude that urinary free cortisol is the most efficient screening method for Cushing's syndrome in hospitalized patients.

Corticosteroid therapy in asthma

Corticosteroids are useful in the treatment of both allergic and idiosyncratic asthma. Although the mechanisms of corticosteroid action in asthma are poorly understood, several possible sites of action have been proposed. Corticosteroids alter the cellular and vascular inflammatory response to bronchial injury, affect catecholamine action on airways, and alter the production of eicosanoids, all of which aid in the resolution of bronchospasm in asthmatic patients. Corticosteroids should only be used for the treatment of asthma after therapeutic levels of methylxanthines and beta agonists have been achieved. Although the optimal doses of corticosteroids in asthma have not been defined, guidelines exist to aid in therapy. In the treatment of status asthmaticus, the intravenous route of administration is preferable. Short courses of corticosteroids may be useful in the treatment of chronic asthma. When long-term corticosteroid therapy is the only option for control of bronchospasm, alternate-day and/or aerosolized corticosteroids are preferable to daily corticosteroids and are associated with fewer side effects. Corticosteroids are useful in the pregnant asthmatic patient when bronchospasm cannot be controlled with bronchodilators. The major risk to the fetus in pregnant asthmatics is hypoxia from uncontrolled bronchospasm, and not from therapy. However, the lowest possible dose of systemic corticosteroids needed to control symptoms, with or without the use of aerosolized corticosteroids, is recommended. All asthmatics who have needed systemic or aerosolized corticosteroids within 6 months prior to surgery should receive preoperative and post-operative corticosteroid therapy. For patients not usually on systemic corticosteroids, conversion to oral prednisone, with a rapid taper is recommended. Side effects from short-term corticosteroid therapy are minimal, with hyperglycemia and psychosis being the major concerns. Long-term steroid therapy has significant side effects, however, and use should be minimized. Suppression of the HPA axis is one of the most potentially dangerous side effects of corticosteroids, and therefore any patient who has been treated with corticosteroids for longer than 4 weeks should be evaluated for possible adrenal suppression.

Golden Syrian hamsters: a new experimental model for adrenal compensatory hypertrophy

We report that adrenal compensatory hypertrophy occurs in the golden syrian hamster, an animal secreting cortisol as the primary adrenal glucocorticoid. This response is seen at 3, 6, 10, and 21 days after unilateral adrenalectomy. The response is present in hypophysectomized hamsters and when endogenous ACTH secretion is suppressed by administration of dexamethasone by im injection or by dexamethasone and ACTH using the Alzet osmotic pump. Administration of either aldosterone alone or in combination with dexamethasone and ACTH by Alzet pump completely blocks adrenal compensatory hypertrophy after unilateral adrenalectomy.

Aldosterone blocks adrenal compensatory hypertrophy in the rat

We report that adrenal compensatory hypertrophy occurs in intact and hypophysectomized anesthetized rats as well as in rats in which endogenous ACTH is suppressed by administration of dexamethasone or of dexamethasone plus low-dose ACTH. However, adrenal compensatory hypertrophy is blocked in intact and hypophysectomized animals when aldosterone alone or the combination of aldosterone, dexamethasone, and ACTH is administered using Alzet pumps. These data support previous reports that questioned the validity of the hypothesis that adrenal compensatory hypertrophy is controlled by the glucocorticoid-ACTH negative feedback system. These results require modification of current hypotheses concerning the mechanism of adrenal compensatory hypertrophy to allow for a central nervous system or other effect of aldosterone.

Strongyloidiasis manifested as asthma

We have described a case of infection with Strongyloides stercoralis manifested as asthma. As a result of treatment with corticosteroids, hyperinfection developed with aggravation of symptoms. The patient's condition improved only after thiabendazole therapy was instituted and corticosteroids were discontinued.