Nap polysomnography in infants with laryngomalacia as a tool to predict treatment strategy

PURPOSE

This study aimed to investigate the role of nap polysomnography (NPSG) in predicting treatment strategies for infants with moderate to severe laryngomalacia and to explore the association between obstructive sleep apnea (OSA) severity, weight gain, and laryngomalacia severity.

METHODS

A retrospective analysis was conducted on infants diagnosed with moderate to severe laryngomalacia who underwent NPSG between January 2019 and June 2023. Clinical variables, NPSG parameters, and treatment decisions were collected. Weight gain rate and its correlation with NPSG indices were assessed. Logistic regression analyses were performed to predict treatment strategies based on NPSG findings.

RESULTS

Of the 39 infants included (median age: 3.3 months), 77% exhibited OSA, with 69% having moderate to severe OSA [apnea-hypopnea index (AHI) > 5/h]. Weight gain rate correlated negatively with indices of OSA severity, including the hypopnea index (HI) and the AHI. In a multiple logistic regression analysis incorporating the severity of OSA (AHI), weight gain rate, and laryngomalacia severity, only AHI predicted the decision for surgical or non-invasive ventilation treatment (OR = 2.1, CI95 [1.6; 2.8], p ≤ 10-4). The weight gain rate was predicted (r2 = 0.28) by the AHI and the presence of retractions of auxiliary inspiratory muscles.

CONCLUSION

This study underscores the importance of NPSG in assessing infants with moderate to severe laryngomalacia. The AHI from NPSG emerged as a potential predictor for treatment decisions and weight gain rate, emphasizing its clinical relevance. These findings advocate incorporating NPSG into the diagnostic and management process for infants with laryngomalacia.

Coping Strategies and Workplace Supports for Peers with Substance Use Disorders

Introduction: Substance use disorder (SUD) peers provide support and navigation through a fragmented treatment system for people who use drugs (PWUD) and those in recovery. While barriers to peers' work are well established, from role ambiguity to stigma surrounding substance use, little research has focused on factors that facilitate peers' work. Methods: We conducted in-depth semi-structured interviews (N=20) with peers as part of an evaluation of a larger project related to the opioid crisis in Western New York. Participants were recruited from a regional peer network via flyers, emails, and a brief presentation. Interviews were conducted in person or by phone, audio recorded, and transcribed. Transcripts were analyzed using thematic content analysis. Results: Peers emphasized two factors: healthy personal coping strategies and strong workplace supports. Coping strategies included a sense of community, setting appropriate boundaries, and self-care routines. At the workplace, peers valued mental and emotional support, as well as professional relationships and organizational policies that made their work easier and supported self-care. For a few peers, professional relationships included advocating on behalf of PWUD by sharing personal experiences of SUD. Conclusions: Peers valued peer colleagues and peer-led organizations, noting how shared experiences of substance use and recovery enabled a unique support system. For peers who lack such support at work, the authors suggest peer networks as an alternative. We also recommend organizational policies and practices to facilitate peers' work, such as promoting peer input and feedback, but further research is needed to measure effects on peer retention and job satisfaction.

Relationship between video head impulse test, ocular and cervical vestibular evoked myogenic potentials, and compartmental magnetic resonance imaging classification in menière's disease

OBJECTIVES/HYPOTHESIS

Currently, it is possible to assess in vivo the morphology of each compartment of the endolymphatic spaces 4 hours after an intravenous administration of gadolinium on magnetic resonance imaging (MRI). The aim of this study was to assess the correlation between otolithic and ampullar functions (cervical vestibular evoked myogenic potential [cVEMP], ocular vestibular evoked myogenic potential [oVEMP], video head impulse test [VHIT]) and delayed inner ear MRI based on a compartmental, anatomically based classification that included the cochlea, the saccule, the utricle, and the ampullas.

STUDY DESIGN

Retrospective case-control study.

METHODS

In this retrospective study, we performed three-dimensional fluid-attenuated inversion recovery sequences with delayed acquisition in 26 healthy subjects and 31 definite Menière's disease (MD) patients. Each subject was then graded on MRI on the basis on cochlear, saccular, utricular, and ampullar hydrops in MD patients. All patients underwent pure-tone audiometry, VHIT, cVEMP, and oVEMP testing.

RESULTS

Cochlear, saccular, utricular, and ampullar hydrops were found on MRI in 88%, 91%, 50%, and 8.5% respectively. We found no significant correlation between the presence of saccular hydrops versus cVEMP, utricular hydrops versus oVEMP, and ampullar hydrops versus VHIT. However, the severity of endolymphatic hydrops on MRI was correlated to the degree of hearing loss.

CONCLUSIONS

We proposed a compartmental, anatomically based classification for endolymphatic hydrops on MRI, which included the whole vestibular compartment. Using this classification, we observed increasing morphological changes as the disease evolved, affecting first the saccule, then the utricle, and finally the ampullas. The severity of vestibular endolymphatic hydrops is only correlated to hearing loss severity.

LEVEL OF EVIDENCE

3 Laryngoscope, 130:E444-E452, 2020.

Spina bifida occulta and aperta: a review of current treatment paradigms

Spina bifida remains a challenging neurosurgical entity to manage despite both an increased awareness of the disease as well as a decreased incidence due to folic acid supplementation. We review the spectrum of neural tube defects, which are the second most common serious congenital defect and the most common of the central nervous system, and discuss the latest management paradigms. The challenges of timely diagnosis and treatment of spina bifida occulta and the latest advances in fetal repair of spina bifida aperta (myelomeningocele) will be discussed. The authors review the literature and share their experience with managing neural tube defects.

Genetic mapping of quantitative trait loci for resistance to Haemonchus contortus in sheep

This paper presents results from a mapping experiment to detect quantitative trait loci (QTL) for resistance to Haemonchus contortus infestation in merino sheep. The primary trait analysed was faecal worm egg count in response to artificial challenge at 6 months of age. In the first stage of the experiment, whole genome linkage analysis was used for broad-scale mapping. The animal resource used was a designed flock comprising 571 individuals from four half-sib families. The average marker spacing was about 20 cM. For the primary trait, 11 QTL (as chromosomal/family combinations) were significant at the 5% chromosome-wide level, with allelic substitution effects of between 0.19 and 0.38 phenotypic standard deviation units. In general, these QTL did not have a significant effect on faecal worm egg count recorded at 13 months of age. In the second stage of the experiment, three promising regions (located on chromosomes 1, 3 and 4) were fine-mapped. This involved typing more closely spaced markers on individuals from the designed flock as well as an additional 495 individuals selected from a related population with a deeper pedigree. Analysis was performed using a linkage disequilibrium-linkage approach, under additive, dominant and multiple QTL models. Of these, the multiple QTL model resulted in the most refined QTL positions, with resolutions of <10 cM achieved for two regions. Because of the moderate size of effect of the QTL, and the apparent age and/or immune status specificity of the QTL, it is suggested that a panel of QTL will be required for significant genetic gains to be achieved within industry via marker-assisted selection.

Cell type-dependent control of NF-Y activity by TGF-beta

Transforming growth factor beta (TGF-beta) is a pluripotent cytokine that regulates cell growth and differentiation in a cell type-dependent fashion. TGF-beta exerts its effects through the activation of several signaling pathways. One involves membrane proximal events that lead to nuclear translocation of members of the Smad family of transcriptional regulators. TGF-beta can also activate MAPK cascades. Here, we show that TGF-beta induces nuclear translocation of the NF-YA subunit of the transcription factor NF-Y by a process that requires activation of the ERK cascade. This results in increased binding of endogenous NF-Y to chromatin and TGF-beta-dependent transcriptional regulation of the NF-Y target gene cyclin A2. Interestingly, the kinetics of NF-YA relocalization differs between epithelial cells and fibroblasts. NIH3T3 fibroblasts show an elevated basal level of phosphorylated p38 and delayed nuclear accumulation of NF-YA after TGF-beta treatment. In contrast, MDCK cells show low basal p38 activation, higher basal ERK phosphorylation and more rapid localization of NF-YA after induction. Thus, NF-Y activation by TGF-beta1 involves ERK1/2 and potentially an interplay between MAPK pathways, thereby opening the possibility for finely tuned transcriptional regulation.

The European working time directive: implications for subspecialty acute care

The requirements of the new deal for junior doctors' hours has meant that many smaller trusts are unable to provide adequate cover on-call for medical and surgical subspecialties. The care of the acute subspecialty patients has, therefore, shifted to general teams in many trusts. We assessed what impact this had upon the outcome of acute urological cases in our district general hospital by prospectively monitoring acute renal colic admissions over a 12-month period and surveyed the provision of services in other regional hospitals. The shift in care of the acute urological patient was associated with considerable morbidity for patients admitted in our hospital. The additional financial burden due to this morbidity was estimated to be 33000 pounds/annum. The implementation of the new deal must be achieved with every care to minimise the clinical and financial costs of withdrawing acute subspecialty services.

Group 2 metabotropic glutamate receptors induced long term depression in mouse striatal slices

We studied the roles of mGlu2/3 receptors (mGlu2/3) in glutamatergic transmission at corticostriatal synapses in mice brain slices. Perfusion of the selective mGlu2/3 agonists LY354740 and L-CCG1 caused the long term depression (LTD) of evoked synaptic responses. Photonic and electronic microscopy showed mGlu2/3 on axonal fibers and glial processes but not on striatal dendrites. mGlu2/3-LTD was independent of synaptic activity and insensitive to specific antagonists of dopamine D1, D2, GABA(B), N-methyl-D-aspartate or adenosine A1 receptors. Manipulation of the cAMP/protein kinase A cascade had no effect on the mGlu2/3-LTD. In contrast, MEK1-2 inhibitors reduced both mGlu2/3 initial depression and LTD suggesting the involvement of the mitogen activated kinase pathway in mGlu2/3-LTD.

Intrathoracic desmoid tumor mimicking primary lung neoplasm

Most reported thoracic desmoid tumors originate from the chest wall. However, intrathoracic desmoid tumors are rare. The pathogenesis of these tumors is unclear but antecedent trauma and operation have been implicated. Desmoid tumors can present either with pain or be incidentally detected on radiographic studies. We describe the case of a 60-year-old woman with an intrathoracic desmoid detected on a routine screening chest roentgenogram who underwent complete surgical resection of the tumor.

Seed size variation and predation of seeds produced by wild and crop-wild sunflowers

The movement of pollen between crop and wild sunflowers (both Helianthus annuus) has led to concerns about the possible introduction of crop transgenes into wild populations. The persistence of crop traits in wild populations will depend in part on the relative fitness of crop-wild hybrid vs. wild plants. Using seeds from two large experimental field plots, we found that seeds produced by crop-wild plants were twice the size of wild seeds and differed in coloration. Head diameter, date of flowering, identity of mother plant, and levels of predispersal predation explained some variation in mean seed size. We hypothesized that postdispersal vertebrate seed predation would be affected by seed size, with hybrid seeds preferentially eaten. In each of three field trials, significantly more hybrid seeds were eaten (62% of hybrid seed; 42% of wild seed). Within the category of wild seeds, larger seeds were preferentially eaten; however among hybrid seeds, predation was not significantly related to seed size. In this study, differential predation thus reduces hybrid fitness and would presumably slow the spread of transgenes into wild populations.

The swallowing and voicing characteristics of pharyngeal dystonia: a single case report

This paper describes the swallowing difficulty and abnormal voicing characteristics of a subject with pharyngeal dystonia. This rare form of dystonia, considered to be a neurological condition resulting in involuntary spasm of the muscles of the pharynx, has not been documented in terms of its effects on the acoustic properties of the voice. This study revealed that during pharyngeal spasm, there are significant delays in voice onset time, a reduction in fundamental frequency, an increased percentage of sub-harmonics and variability in the amplitude perturbation quotient as well as shimmer. There was also evidence of these characteristics during periods of 'spasm-free' voice production, suggesting that the condition might be more consistent than what the subject described. Resonance disturbances were observed in spasm, which might explain the 'hollow' and affected voice quality. The subject also reported severe swallowing difficulties during the periods of spasm, characterised by a tight constriction at the level of the subject's throat. It is clear that an abnormality at the level of the cricopharyngeal muscle has a dual effect on the acoustic properties of the voice and on swallowing.

Epstein-Barr virus-associated high-grade B-cell lymphoma of mucosal-associated lymphoid tissue in a 9-year-old Boy

We report an unusual case of Epstein-Barr virus (EBV)-associated mucosal-associated lymphoid tissue (MALT) lymphoma involving the lungs, kidneys, and axillary lymph nodes in a child with congenital hypoadrenalism and panhypopituitarism. The patient presented with an aggressive clinical course and histologic evolution. Initial biopsies (1994) of the lung and kidney revealed histologic features of low-grade B-cell MALT lymphoma with lymphoepithelial lesions within the renal tubules and bronchial epithelium. Subsequent biopsies (1996, 1997, and 1999) revealed progressively greater cytologic atypia, polymorphism, and necrosis; an increased mitotic rate; and a preponderance of large cells, indicative of progression from a low-grade to a high-grade MALT lymphoma. Immunophenotyping of the lung and lymph node lesions revealed identical surface marker profiles: cells were CD19(+), CD20(+), immunoglobulin (Ig) G(+), kappa(+), lambda(-), CD5(-), CD10(-), CD23(-), and IgM(-), and also negative for T-cell markers. Genotypic analysis demonstrated the presence of immunoglobulin heavy chain rearrangement and monoclonality of EBV in the lung lesion by Southern blot hybridization and polymerase chain re()action (PCR). The clinicopathologic features suggest that these lesions might represent an immunosupression-related continuum of low-grade to high-grade MALT lymphomas. Infection with EBV may have contributed to this tumor's aggressive clinical and histologic evolution.

Congenital acute T lymphoblastic leukaemia: report of a case with immunohistochemical and molecular characterisation

A newborn infant with congenital T cell lymphoblastic leukaemia presented with hepatosplenomegaly and pancytopenia at birth and died on the 21st day of multi-organ failure. Biopsy and necropsy examination showed extensive atypical lymphoid infiltrates in the lungs, liver, spleen, kidneys, lymph nodes, and bone marrow. Immunohistochemically, the lymphoid cells were TdT+, CD3+, CD45RO+, and CD10-, CD79a-, CD20-. Genotypic analysis using polymerase chain reaction showed T cell receptor gamma chain gene rearrangement and absence of immunoglobulin heavy chain gene rearrangement. This appears to be the first documented case of congenital T cell lymphoblastic leukaemia. The case had unusual histological and immunogenotypic features, disseminated early, and pursued a highly aggressive course. Consideration of the diagnosis is of paramount importance. The immunophenotypic studies and molecular characterisation of such congenital leukaemias are critical in arriving at a definite diagnosis.

A comparison of thoracic and lumbar epidural techniques for post-thoracoabdominal esophagectomy analgesia

PURPOSE

To compare thoracic epidural analgesia (TEA) using a bupivacaine/fentanyl mixture and lumbar epidural analgesia (LEA) with morphine, in respect to the time to extubation and the quality of post-operative analgesia, in patients having thoracoabdominal esophagectomy.

METHODS

Twenty two patients scheduled for elective thoracoabdominal esophagectomy were randomized to TEA or LEA. Postoperatively, the TEA group received Patient Controlled Epidural Analgesia (PCEA) with bupivacaine 0.125% and 5 microg x ml(BI) fentanyl, and the LEA group received PCEA with 0.2 microg x ml(BI) morphine. A blinded observer assessed criteria for tracheal extubation and the time of tracheal extubation was recorded. Early extubation was defined as tracheal extubation within four hours postoperatively. Visual analogue pain scores at rest (Static Visual Analogue Pain Scores, SVAPS) and with movement (Dynamic Visual Analogue Pain Scores, DVAPS) were recorded at 1, 6, 12, 18 and 24 hr post-extubation. Failure of the epidural protocol (FEP) was defined as a request for additional analgesia.

RESULTS

Tracheal extubation was achieved in 70% of the LEA and 100% of the TEA at four hours postoperatively (P=NS). However, the TEA group achieved earlier extubation times when assessed with log rank testing (P = 0.01). By six hours post-extubation FEP had occurred in 50% of the LEA group but in none of the TEA group (P = 0.01). Mean SVAPS and DVAPS were lower in the TEA than in the LEA group at all measured times (P < 0.01).

CONCLUSION

This study has demonstrated superior pain control in patients undergoing thoraco-abdominal esophagectomy treated with TEA than with LEA, particularly for pain with movement. Tracheal extubation occurred earlier in the TEA group, but this difference was not significant at four hours postoperatively.

Neuropathies masquerading as an epidural complication

PURPOSE

The purpose of this report is to emphasise the role of the Acute Pain Service in managing local anaesthetic epidural infusions for postoperative pain management, the importance of vigilant monitoring, and to offer some guidelines to using local anaesthetic epidural infusions.

CLINICAL FEATURES

A 34-yr-old man with long-standing insulin dependent diabetes mellitus underwent a total proctocolectomy for inflammatory bowel disease. A T9-10 epidural catheter was placed prior to induction of general anaesthesia. Postoperatively, a continuous epidural infusion of fentanyl/bupivacaine was used for postoperative pain management. Total lithotomy time was four hours. On day four he was noted to have complete right sided femoral and left sided lateral femoral cutaneous nerve of thigh neuropathies. A computerised tomography scan and a magnetic resonance imaging excluded a central lesion. Electromyelography confirmed peripheral nerve injuries.

CONCLUSION

This patient's neurological deficits were not due to the epidural analgesia. However, epidural infusion of local anaesthetic caused a delay in recognising a potential neurological complication. When using local anaesthetic epidural infusions, it is important to exclude other causes of motor block before attributing it to the local anaesthetic.

Preoperative factors of prognostic significance in gastric cancer

This study was undertaken to investigate the ability of local anatomical and primary histological features of gastric cancers, as well as DNA analysis, to predict prognosis. Using multivariate analysis, results indicate that location of a tumor in the gastric cardia, poor differentiation, involvement of adjacent organs, and aneuploidy are all independent predictors of survival. All of the factors studied can be determined by endoscopic procedures preoperatively on patients with gastric cancers and could be helpful in selecting some patients for perioperative adjunctive therapies.

O6-methylguanine-DNA methyltransferase in normal and malignant tissue of the breast

An important component of high-dose chemotherapy/autologous bone marrow support regimens for adjuvant treatment of breast cancer is carmustine. Preclinical studies have shown that the level of the DNA repair protein O6-methylguanine-DNA methyltransferase is correlated with the resistance of cultured human tumor cells to this drug, but little is known about transferase levels of breast tissue in vivo. We measured the DNA repair activity in 80 tissue samples from 65 patients, including normal, abnormal, benign, and malignant specimens. Wide interindividual variations was observed and average transferase levels were similar in normal and benign tissue. However, transferase levels were significantly elevated in stage I-IV disease. In addition, the frequency of samples with no detectable transferase was greatly reduced in this malignant group, and transferase was positively correlated with the presence of positive nodes, a marker for disease progression. In contrast, transferase levels were not correlated with age or estrogen receptor status, and the levels in normal tissue did not vary between patients with benign or malignant disease. These results suggest that this DNA repair activity may be increased in breast cancer relative to normal tissue and encourage further study of the predictive value of transferase measurements in high-dose chemotherapy/autologous bone marrow transplant for breast cancer.

Let us now revisit prepaid group practice

American medicine will soon enter health care reform. The Clinton Administration's Task Force on Health Care Reform is likely to introduce change that relies heavily on managed care, a field now dominated by the health insurance industry. Physicians can manage health care themselves by forming Prepaid Group Practices (PGPs). PGPs combine health insurance functions with physician managed health care. They can negotiate directly with health care purchasers, thereby abrogating the commercial health insurance industry.

The value of flow cytometric analysis in patients with gastric cancer

Tumors in the gastric cardia and the body/antrum were studied to determine the effect of ploidy and S-phase fractions on patient survival. Forty-two percent of tumors were located in the cardia and 58% in the body/antrum. Nodal metastases occurred more often with cardia tumors than with body/antrum tumors (86% vs 65%). Aneuploidy occurred more frequently in patients with cardia tumors than in patients with body/antrum tumors (39% vs 20%). Metastasis to lymph nodes was more common in patients with aneuploidy than in patients with diploidy (31% vs 7%). S-phase fractions were not different between aneuploid and diploid tumors. More patients with diploid cancer were alive at 5 years than were patients with aneuploid tumors (90% vs 10%). We conclude that primary cellular differences in gastric tumors of the cardia or body/antrum determine patient survival.

Prognostic Factors in Node-Negative Breast Cancer

One hundred patients with node-negative breast cancer were examined to analyze the influence of tumor size, nuclear grade, and DNA content determined by flow cytometry on overall survival. Patients with diploid cancers lived significantly longer than those with aneuploid cancers (126 +/- 8 vs 80 +/- 11 months). Patients with an S-phase fraction less than 10% lived significantly longer than those with S-phase fractions 10% or greater (122 +/- 8 vs 85 +/- 10 months). Tumor size had the major impact on survival, and multivariate analysis of variance by the Cox proportional hazards model showed the greatest effect on prognosis. Tumor grade did not significantly influence overall survival.

Expression of the amiloride-blockable Na+ channel by RNA from control versus aldosterone-stimulated tissue

The amiloride-blockable Na+ channel was expressed in Xenopus oocytes injected with total RNA isolated from the toad urinary bladder. This system was used to investigate mechanisms that mediate the natriferic action of aldosterone. Incubation of the epithelium with aldosterone for 3 h doubled its channel activity but did not increase the ability of isolated RNA to express functional channels in oocytes. A 20-h incubation with the hormone produced an additional increase of Na+ transport across the intact epithelium and also augmented the channel activity expressed in oocytes by nearly 10-fold. The data are in agreement with our model that aldosterone enhances the apical Na+ permeability of tight epithelia by a short term activation of pre-existing channels, followed by chronic induction of new channel protein. Blocking methyl transfer reactions, previously shown to inhibit the natriferic action of aldosterone in tight epithelia, did not alter the basal or aldosterone-induced response in oocytes.

Prefrontal sonic treatment: MR findings

The authors describe the use of MR in a patient who underwent prefrontal sonic treatment for relief of intractable headaches. MR demonstrated well-demarcated regions of encephalomalacia within the white matter of the frontal lobe (with relative sparing of cortex) in a characteristic conical volume that corresponded to the insonified regions.

Pathogenesis of acute pulmonary inflammation in strain 2 and strain 13 guinea pigs

An acute inflammatory response was elicited in the lungs of strain 2 and 13 guinea pigs following immunization and aerosol challenge with ovalbumin. The pulmonary inflammatory response, characterized by hemorrhage and influx of inflammatory cells, progressed from initiation at 12-hours postchallenge through resolution at 96-hours postchallenge. Inflammatory and immunoregulatory cells, recovered by bronchoalveolar lavage, showed quantitative changes in their relative contribution to the bronchoalveolar cell infiltrate over the course of inflammation. Changes in concentrations of macrophages and T cells, in particular, are discussed in terms of their possible contributions to initiation and resolution of acute pulmonary inflammation.

Effect of an inhibitor of DNA methylation on T cells. I. 5-Azacytidine induces T4 expression on T8+ T cells

Maturing thymocytes express a series of cell surface glycoproteins which can be identified by monoclonal antibodies. The stage II or common thymocyte expresses the phenotype T4+T8+T6+T3-. In response to unknown signals, but presumably involving interactions with products of the major histocompatibility complex, the thymocyte suppresses either the T8 or T4 gene, becoming committed to the T4+T8- or T4-T8+ phenotype. With maturation, the thymocyte also becomes T6-T3+. To study whether DNA methylation may be involved in regulating expression of these determinants in mature T cells, we treated cloned interleukin 2-dependent T8- and T4-bearing T cells with 5-azacytidine (5-azaC), a nucleoside analog which inhibits methylation of newly synthesized DNA. In this report, we show that T8+ T cells treated with 5-azaC express the phenotype T8+T4+T6-T3+. Treatment of the same cells with hydroxyurea, an inhibitor of DNA synthesis, failed to induce T4 on T8+ cells. These results suggest that expression of the T4 gene may be suppressed by DNA methylation in mature T8+ cells.

Effect of an inhibitor of DNA methylation on T cells. I. 5-Azacytidine induces T4 expression on T8+ T cells

Maturing thymocytes express a series of cell surface glycoproteins which can be identified by monoclonal antibodies. The stage II or common thymocyte expresses the phenotype T4+T8+T6+T3-. In response to unknown signals, but presumably involving interactions with products of the major histocompatibility complex, the thymocyte suppresses either the T8 or T4 gene, becoming committed to the T4+T8- or T4-T8+ phenotype. With maturation, the thymocyte also becomes T6-T3+. To study whether DNA methylation may be involved in regulating expression of these determinants in mature T cells, we treated cloned interleukin 2-dependent T8- and T4-bearing T cells with 5-azacytidine (5-azaC), a nucleoside analog which inhibits methylation of newly synthesized DNA. In this report, we show that T8+ T cells treated with 5-azaC express the phenotype T8+T4+T6-T3+. Treatment of the same cells with hydroxyurea, an inhibitor of DNA synthesis, failed to induce T4 on T8+ cells. These results suggest that expression of the T4 gene may be suppressed by DNA methylation in mature T8+ cells.