Low-dose daily subcutaneous interleukin-2 in combination with highly active antiretroviral therapy in HIV+ patients: a randomized controlled trial

PURPOSE

Previous studies with intermittent interleukin-2 (IL-2) therapy using intermediate and high levels of IL-2 have demonstrated significant increases in the CD4 + T cell count in HIV-infected patients. Intermittent regimens are amenable to outpatient use, but severe adverse events are frequently experienced with intermediate- and high-dose levels of IL-2. Therefore in this study, the effect of daily, subcutaneous low-dose IL-2 therapy on safety and immunological endpoints was investigated to determine whether immunological benefit could be achieved without toxicity in HIV-infected patients also receiving highly active antiretroviral therapy (HAART).

METHOD

A total of 115 patients were enrolled in the trial. Fifty-six asymptomatic HIV-infected patients who had CD4 + T cell counts less than 300 cells/microL at screening and a stable HIV viral load received low-dose IL-2 (1.2 million IU [MIU]/m 2 beginning dose) once daily in conjunction with HAART (IL-2 group). Fifty-nine patients received HAART alone (control group).

RESULTS

A dramatic effect of IL-2 on the natural killer (NK) cell population was observed with mean increases of 156 cells/microL in the IL-2 group compared to 19.93 cells/microL in the control group (p <.001). Additionally, IL-2-treated patients experienced a statistically significant increase in the mean percentage of CD4 + T cells (3.52% increase) when compared to control patients (1.33% increase) (p <.001). The expanded CD4 + T cell population was primarily of the naive phenotype, with mean increases of 4.53% for the IL-2 group and 0.31% for the control group (p <.001 for between-group difference). In addition, a higher proportion of IL-2-treated patients (67%) compared to control patients (33%) achieved increases of greater than 50% in the CD4+ T cell count (p =.08). Adverse events of grade 3 or grade 4 toxicity were infrequent in the current study and were substantially lower by comparison to those in studies of intermittent dose IL-2 therapy. Also, negligible changes in the HIV viral load from baseline to final measurement were observed in both groups. A trend toward a reduced number of modifications of antiretroviral therapy was apparent in the IL-2 group when compared to control patients.

CONCLUSION

Daily, low-dose subcutaneous IL-2 therapy in conjunction with HAART is safe and well tolerated and is effective in expanding lymphocyte cell types including NK cells and naive T cells in individuals who have <300 CD4+ T cells.

In vivo assessment of antiviral reactivity in chronic HIV infection

PURPOSE AND METHOD

Chronic infection with HIV renders individuals incapable of mounting an effective host antiviral response, as defined by in vitro assays. Therefore, to determine whether antiviral reactivity could be detected in vivo, we interrupted effective antiviral treatment prospectively in nine chronically infected aviremic individuals. Low-dose interleukin-2 (IL-2) was administered before and after treatment interruption to compensate for any potential IL-2 production deficiency. In vivo antiviral reactivity was monitored subsequent to the interruption of antiviral therapy via viral and lymphocyte dynamics. The study was terminated when the plasma HIV RNA concentration reached a plateau, defined as four successive determinations that were <25% from the mean.

RESULTS

Plasma viral relapse occurred in all participants; reaching a peak concentration within 2.5 weeks. However, over the subsequent 2 weeks viremia was reduced an order of magnitude coincident with a 2-fold lymphocytosis of the CD8 + T cell subset. A second treatment interruption resulted in attenuation of the peak and trough virus concentrations by <10-fold in 3 of 4 participants, while the CD8 + T cell concentrations remained elevated.

CONCLUSION

These findings indicate that chronic HIV infection prior to successful antiviral therapy does not preclude host antiviral reactivity. In addition, in vivo antiviral reactivity as revealed by viral and lymphocyte dynamics after antiviral treatment interruption can be useful to monitor the efficacy of different therapies.

PU.1 inhibits GATA-1 function and erythroid differentiation by blocking GATA-1 DNA binding

The lineage-specific transcription factors GATA-1 and PU.1 can physically interact to inhibit each other's function, but the mechanism of repression of GATA-1 function by PU.1 has not been elucidated. Both the N terminus and the C terminus of PU.1 can physically interact with the C-terminal zinc finger of GATA-1. It is demonstrated that the PU.1 N terminus, but not the C terminus, is required for inhibiting GATA-1 function. Induced overexpression of PU.1 in K562 erythroleukemia cells blocks hemin-induced erythroid differentiation. In this system, PU.1 does not affect the expression of GATA-1 messenger RNA, protein, or nuclear localization. However, GATA-1 DNA binding decreases dramatically. By means of electrophoretic mobility shift assays with purified proteins, it is demonstrated that the N-terminal 70 amino acids of PU.1 can specifically block GATA-1 DNA binding. In addition, PU.1 had a similar effect in the G1ER cell line, in which the GATA-1 null erythroid cell line G1E has been transduced with a GATA-1-estrogen receptor fusion gene, which is directly dependent on induction of the GATA-1 fusion protein to effect erythroid maturation. Consistent with in vitro binding assays, overexpression of PU.1 blocked DNA binding of the GATA-1 fusion protein as well as GATA-1-mediated erythroid differentiation of these G1ER cells. These results demonstrate a novel mechanism by which function of a lineage-specific transcription factor is inhibited by another lineage-restricted factor through direct protein-protein interactions. These findings contribute to understanding how protein-protein interactions participate in hematopoietic differentiation and leukemogenesis. (Blood. 2000;96:2641-2648)

Inhibitory effect of cystic fibrosis sputum on adenovirus-mediated gene transfer in cultured epithelial cells

Effective gene transfer to the airway epithelial cells of individuals with cystic fibrosis (CF) requires gene therapy vectors to effectively penetrate the mucous lining of the airways of these patients. In this study, we examined the effects of the aqueous sol fraction of sputum recovered from CF patients (CF sol) on adenovirus (Ad)-mediated gene transfer to cultured epithelial cells. Sputum collected from patients with CF was separated into aqueous sol and gel fractions by ultracentrifugation and the sol fraction from different individuals was pooled. To determine if CF sol affects Ad-mediated transfection, Fisher rat thyroid (FRT) epithelial cells or normal human bronchial epithelial (NHBE) cells were infected with an Ad encoding beta-galactosidase (Ad2/betagal-2) in the presence or absence of the pooled CF sol. Transfection efficiency was determined by measuring beta-Gal activity. CF sol significantly inhibited Ad2-mediated gene transfer in a dose-dependent manner when the vector was incubated with CF sol prior to exposure to the cells. In contrast, preincubation of the cells with the sol was without effect. The inhibition of Ad-mediated gene transfer by CF sol was not related to its low pH, was abrogated by preadsorption with an Ad2 serotype vector, and was neutralized by heat treatment, but was not affected by treatment with protease inhibitors. Analysis of CF sol fractions from seven different individuals with CF showed inhibition of Ad-mediated gene transfer in four of the seven samples tested and, further, the inhibitory effect was correlated with the presence of Ad-specific antibodies. We conclude that preexisting adenovirus-specific antibodies present in some of the patient samples were the predominant factor inhibiting Ad-mediated gene transfer.

Gamma knife radiosurgery for trigeminal neuralgia: experience at the Barrow Neurological Institute

Forty-three patients with trigeminal neuralgia (TN) unresponsive to pharmacologic treatment and/or prior invasive procedures underwent stereotactic radiosurgery with the Gamma Knife (GK). Outcome was evaluated by a standardized questionnaire mailed to each patient. The mean follow-up was 9 months. Fifteen patients (35%) reported no trigeminal pain and were no longer taking medication. Three patients (7%) experienced occasional pain, but were no longer taking medication. In 15 patients (35%), pain improved and was adequately controlled by medication, often in lower dosages than preoperatively. Pain was reduced in 9 patients (21%), but their symptoms were still inadequately controlled by drug therapy, and 1 patient (2%) reported no pain relief after treatment. Three patients (7%) described new facial numbness, but in none was this bothersome. GK radiosurgery for TN appears to have minimal morbidity, although the success rate may be slightly lower than that of other operative procedures. More patients and longer follow-up are needed before drawing final conclusions regarding efficacy and complications.

Autoantibodies to the flavoprotein subunit of succinate dehydrogenase: analysis of specificity in autoimmune thyroid disease

OBJECTIVE

Thyroid-associated ophthalmopathy is a progressive eye disorder affecting the extraocular muscle and orbital connective tissue and is considered to have an autoimmune aetiology. A recent study reported a close relationship between serum antibodies against the flavoprotein subunit of succinate dehyhdrogenase (SDHFp) and active thyroid-associated ophthalmopathy involving eye muscle damage. The aim of the present study was to develop a sensitive and quantitative radiobinding assay for the detection of antibodies to the flavoprotein subunit of succinate dehydrogenase and to use this to determine the distribution of antibodies in different patient groups.

DESIGN AND PATIENTS

Serum samples from the following patient groups were analysed: 20 systemic lupus erythematosus; 20 Addison's disease; 26 autoimmune hypothyroidism; 28 Graves' hyperthyroidism; 12 pretibial myxoedema; 25 thyroid-associated ophthalmopathy. Sera from 20 healthy subjects were used as controls. [35S]-labelled succinate dehydrogenase flavoprotein was produced in an in vitro transcription-translation system and subsequently used in immunoprecipitation experiments with sera from patient and control groups to test for the presence of antibodies to the flavoprotein.

RESULTS

Succinate dehydrogenase flavoprotein antibodies were detected in five of the 20 (25%) patients with Addison's disease, six of the 20 (30%) with systemic lupus erythematosus, five of the 26 (19%) with autoimmune hypothyroidsm, six of the 28 (21%) with Graves' hyperthyroidism, two of the 12 (17%) with pretibial myxoedema and three of the 25 (12%) with thyroid-associated ophthalmopathy. The frequencies of flavoprotein antibodies were significantly greater than controls (P-value < 0.05) for patients with systemic lupus erythematosus (P = 0.02), but not for patients with either Addison's disease (P = 0.05), pretibial myxoedema (P = 0.13), Graves' hyperthyroidism (P = 0.07), autoimmune hypothyroidism (P = 0.06) or thyroid-associated ophthalmopathy (P = 0.24). For the patients with thyroid-associated ophthalmopathy, the frequency of SDHFp antibodies did not appear to be related to the length of time from diagnosis: the group containing samples taken less than one year from diagnosis showed no increased frequency of SDHFp antibodies when compared to controls (P = 0.10), with three of the 18 (17%) patients being positive. With respect to seven patients with thyroid-associated ophthalmopathy diagnosed for more than a year, SDHFp antibodies were not detected in any of their serum samples. In addition, the clinical severity of the disease, as recorded by the NOSPECS classification, did not correlate with the frequency of SDHFp antibodies: P = 0.13, 0.33 and 0.38, respectively, for patients with Grade II, III and IV ophthalmopathy. Similar results were also found in the case of patients with pretibial myxoedema and eye disease: P = 0.06 for patients with Grade III ophthalmopathy and, SDHFp antibodies were not detected in any of the sera taken from patients with Grade IV ophthalmopathy. In addition, no association was found between disease duration and the frequency of antibodies to the flavoprotein in this patient group.

CONCLUSIONS

Our results indicate that succinate dehydrogenase flavoprotein antibodies are not a suitable marker for thyroid-associated ophthalmopathy, at least with the assay system used, as they can be found in patients who do not have eye disease and therefore lack the disease specificity required of a diagnostic tool.

Experimental analysis of chaotic neural network models for combinatorial optimization under a unifying framework

The aim of this paper is to study both the theoretical and experimental properties of chaotic neural network (CNN) models for solving combinatorial optimization problems. Previously we have proposed a unifying framework which encompasses the three main model types, namely, Chen and Aihara's chaotic simulated annealing (CSA) with decaying self-coupling, Wang and Smith's CSA with decaying timestep, and the Hopfield network with chaotic noise. Each of these models can be represented as a special case under the framework for certain conditions. This paper combines the framework with experimental results to provide new insights into the effect of the chaotic neurodynamics of each model. By solving the N-queen problem of various sizes with computer simulations, the CNN models are compared in different parameter spaces, with optimization performance measured in terms of feasibility, efficiency, robustness and scalability. Furthermore, characteristic chaotic neurodynamics crucial to effective optimization are identified, together with a guide to choosing the corresponding model parameters.

Do-not-resuscitate orders in the operating room: required reconsideration

Advances in medical technology are giving health care providers the tools with which to keep patients alive for longer and longer periods of time. However, in our struggle to keep patients alive, we must not forget that the patient is the one who controls his or her own destiny. Advance directives and do-not-resuscitate orders are becoming more commonplace as patients strive to make their wishes known to all who care for them. The use of such orders in the operating room has historically been a hotbed of controversy because it appears contrary to the necessity of surgery in the first place. Surgeons, anesthetists, operating room nurses, and others all have concerns regarding this issue, and they will be discussed here. The answer to the dilemma lies in a policy of "required reconsideration" to examine all factors of the do-not-resuscitate order and its applicability to the situation at hand.

Gamma knife radiosurgery for trigeminal neuralgia: the initial experience of The Barrow Neurological Institute

PURPOSE

To assess the efficacy and complications of Gamma Knife radiosurgery for trigeminal neuralgia.

METHODS AND MATERIALS

The Barrow Neurological Institute (BNI) Gamma Knife facility has been operational since March 17, 1997. A total of 557 patients have been treated, 89 for trigeminal neuralgia (TN). This report includes the first 54 TN patients with follow-up exceeding 3 months. Patients were treated with Gamma Knife stereotactic radiosurgery (RS) in uniform fashion according to two sequential protocols. The first 41 patients received 35 Gy prescribed to the 50% isodose via a single 4-mm isocenter targeting the ipsilateral trigeminal nerve adjacent to the pons. The dose was increased to 40 Gy for the remaining 13 patients; however, the other parameters were unvaried. Outcome was evaluated by each patient using a standardized questionnaire. Pain before and after RS was scored as level I-IV per our newly-developed BNI pain intensity scoring criteria (I: no pain; II: occasional pain, not requiring medication; III: some pain, controlled with medication; IV: some pain, not controlled with medication; V: severe pain/no pain relief). Complications, limited to mild facial numbness, were similarly graded by a BNI scoring system.

RESULTS

Among our 54 TN patients, 52 experienced pain relief, BNI score I in 19 (35%), II in 3 (6%), III in 26 (48%), and IV in 4 (7%). Two patients (4%) reported no relief (BNI score V). Median follow-up was 12 months (range 3-28). Median time to onset of pain relief was 15 days (range 0-192), and to maximal relief 63 days (range 0-253). Seventeen (31%) noted immediate improvement (</= 24 h). Prior to RS, all patients were on pharmacologic therapy felt to be optimal or maximal. Twenty-two (41%) were able to stop medications entirely (BNI score I or II). Another 16 (30%), with BNI Score III relief, decreased medication intake by at least 50%. Patients with classical TN pain symptoms were more likely to stop medications than those with atypical features, 49% (21 of 43) versus 9% (1 of 11). This difference was significant at p = 0.040. Statistically, the finding most predictive for pain relief was new facial numbness following RS. Each of the 5 patients with new numbness after RS developed BNI score I relief, contrasting with 35% for the 49 patients with no new numbness (p = 0.019). Complications have been limited to delayed, mild facial sensory loss. Before RS, 17 patients had numbness from prior invasive procedures, none of whom reported a worse numbness score after treatment. Thirty-seven patients had no facial numbness at the time of RS, of whom 5 developed facial hypesthesia. Each rated this as "mild, not bothersome." There have been no other sequellae.

CONCLUSION

RS is an effective treatment, and is the least invasive nonpharmacologic therapy for TN. It carries a small risk of mild facial hypesthesia, a side effect which, somewhat ironically, may be desirable, because it appears to correlate favorably with an excellent pain response. We currently include radiosurgery among the appropriate options for TN patients who have failed optimal medical management, with or without prior invasive neurosurgical procedures. We present here BNI scoring systems for pain intensity and facial numbness. These have proved simple and reliable, have facilitated data collection, rendered analysis more objective, and improved our ability to discuss results with patients and colleagues.

Effect of Soil Depth and Moisture on the Vertical Distribution of Steinernema riobrave (Nematoda: Steinernematidae)

The effect of soil moisture on the distribution of Steinernema riobrave in a sand column was determined. Larvae of Pectinophora gossypiella were used to detect S. riobrave infective juveniles (IJ) in each 2.5-cm section of 30-cm-long soil columns. Soil moisture was determined for each section and related to the numbers of nematodes recovered from infected insect baits. Infective juveniles of S. riobrave applied on the sand column surface showed some degree of positive geotaxis. IJ in soil columns with a consistent moisture gradient grouped in the upper 12.7 cm within a water potential range of 40 to 0.0055 MPa (2% to 14% moisture). Nematodes in sand columns that were gradually dehydrating moved down the soil column, aggregating on the 28th day between 15-23 cm in depth. Nematode redistribution over time allowed IJ to remain within a water potential range of 0.1 to 0.012 MPa (5.2% to 9.5% moisture).

Self-evaluation maintenance in a larger social context

Two studies extended Tesser's (1988) Self-evaluation Maintenance (SEM) model to include two close others and to examine the implications of intermediate performances on self-definition. Both demonstrated that when outperformed by both close others, participants rated activities low in self-relevance. When participants outperformed both close others, relevance was moderate or high. When participants were superior to one close other, but inferior to the other, relevance was low or moderate. When participants were uncertain about relative performances, and when there was disagreement over relative performances among the two close others and participants, ratings of relevance were attenuated as a means of protecting participants' self-evaluations. Results are discussed in terms of the importance of extending the SEM model to the larger social network.

Serotonin, dieting, and bulimia nervosa

Dieting is a common behaviour which may trigger eating disorders such as bulimia nervosa in predisposed subjects. We found that in healthy women moderate dieting for 3 weeks lowered plasma concentrations of the 5-HT precursor, L-tryptophan (TRP) and impaired brain 5-HT neurotransmission as judged by 5-HT neuroendocrine tests. In recovered female subjects with a history of bulimia nervosa we found that TRP depletion produced by an amino acid mixture lacking TRP caused a temporary return of depressive symptoms together with concerns about weight and shape and fear of loss of control of eating. Taken together the data suggest that dieting-induced decreases in TRP availability may trigger the development of bulimia nervosa is susceptible individuals.

Immunogene therapy for murine melanoma using recombinant adenoviral vectors expressing melanoma-associated antigens

Adenoviral vectors expressing tumor-associated antigens can be used to evoke a specific immune response and inhibit tumor growth. In this study, we tested the efficacy of adenoviral vectors encoding human gp100 (Ad2/hugp100), murine gp100 (Ad2/mugp100), or murine TRP-2 (Ad2/muTRP-2) for their ability to elicit a specific cellular immune response and inhibit the growth of B16 melanoma tumor cells in the mouse. C57BL/6 mice were immunized with Ad2/hugp100, Ad2/mugp100, or Ad2/muTRP-2 either 2 weeks prior to B16-F10 tumor challenge (prophylactic treatment) or 3 days after tumor challenge (active treatment). Ad2/hugp100 and Ad2/muTRP-2 administered to two or more intradermal (i.d.) sites inhibited subsequent subcutaneous tumor growth in > or = 80% of the mice and elicited an antigen-specific cytotoxic T lymphocyte response, whereas other administration routes were not as effective. Ad2/mugp100 administered to two i.d. sites did not inhibit tumor growth or provoke cellular immunity. Immunization was less effective with active treatment where tumor growth was not significantly inhibited by a single dose of either Ad2/muTRP-2 or Ad2/hugp100. However, increasing the number of intradermal immunization sites and the number of doses resulted in progressive improvements in protection from tumor growth in the active treatment model. In conclusion, breaking host tolerance to elicit protective immunity by using adenoviral vectors expressing melanoma-associated antigens is dependent upon the choice of antigen, the site of administration, and the number of doses. These observations provide insights into the clinical applicability of adenoviral vaccines for immunotherapy of malignant diseases.

Provocative use testing of methyldibromo glutaronitrile in a cosmetic shampoo

Methyldibromo glutaronitrile (1,2-dibromo-2,4-dicyanobutane, MDGN) is a component of Euxyl K400, a broad-spectrum preservative increasingly used in cosmetics over the last 10 years. Contact allergy to MDGN is not uncommon, with leave-on cosmetics and moistened toilet tissue being the most important sources. Rinse-off products have rarely been reported to elicit allergic reactions in patients sensitized to MDGN and shampoos have only been implicated in hairdressers. To determine whether subjects sensitized to MDGN would react in a provocative use test with a shampoo containing the preservative, we asked 12 pre-sensitized subjects to use a shampoo containing 0.02% MDGN for a period of 9-13 weeks. During this time, none of the subjects showed any skin reactions indicative of contact allergy. The results of this study provide evidence to support that a shampoo product containing 0.02% MDGN may safely be used by most individuals who are presensitized to MDGN.

Domain growth in ternary fluids: A level set approach

We analyze phase separation in ternary systems in the asymptotic hydrodynamic regime when the volume fractions and concentrations are constant. The multiphase Navier-Stokes equations are solved using a level set method. A new projection method was developed to treat multiple junctions for systems with more than two phases. It is found that surface tension ratios can alter the growth mechanism of a minority phase in the presence of two majority phases. When the minority phase wets the interface of the majority phases the domain growth rate of all three phases is initially similar to that of a symmetric binary fluid but slows down at later times.

Modelling a loss event: effect of imagined bereavement on the hypothalamic-pituitary-adrenal axis

BACKGROUND

Loss events are the stressors most closely associated with the onset of depressive illnesses. The acute cortisol response to loss has been little studied although it could be an important mediator of the effects of environmental stress on psychological state.

METHODS

The salivary cortisol response to an established negative mood induction procedure involving music and an imagined bereavement was measured in 30 healthy volunteers.

RESULTS

Considerable but transient mood lowering in response to the negative mood induction was associated with a small increase in cortisol output over 30 min.

CONCLUSIONS

This procedure has some potential as a tool to investigate individual differences in the neuroendocrine response to loss events, but this is limited. There remains a need for laboratory models of relevant psychosocial stressors in mood disorders research.

Impaired regulation of brain serotonin function during dieting in women recovered from depression

BACKGROUND

Amino acid mixtures that lower brain availability of the serotonin (5-HT) precursor tryptophan produce acute depressive relapse in women with a history of major depression. Dieting also lowers brain tryptophan availability, but its effects on brain 5-HT function in recovered depressed women have not been studied.

AIM

To test the hypothesis that women with a history of major depression would show impaired regulation of brain 5-HT function during a period of dieting-induced tryptophan depletion.

METHOD

Women with and without a history of major depression were placed on a daily 1000 kcal (approximately 4200 kj) diet for three weeks. Before the diet and in the final week we measured fasting plasma tryptophan levels and the prolactin response to an intravenous tryptophan challenge.

RESULTS

Dieting lowered plasma tryptophan levels equivalently in women with and without a history of depression. In women without a history of depression, dieting also increased the prolactin response to tryptophan. This increase did not occur in women with a history of depression.

CONCLUSIONS

Women with a history of depression showed impaired regulation of brain 5-HT function in response to dieting.

Human cord blood progenitors sustain thymic T-cell development and a novel form of angiogenesis

There is growing interest in using human umbilical cord blood (CB) for allogeneic bone marrow transplantation (BMT), particularly in children. Thus, CB has been identified as a rich source of hematopoietic progenitors of the erythroid, myeloid, and B-cell lineages. Whether CB blood cells engrafting in the BM space also comprise T-cell progenitors capable of trafficking to the thymus and reconstituting a functional thymopoiesis in young recipients is presently unknown. Here, we show that CB progenitors, engrafted in the BM of immunodeficient mice, sustain human thymopoiesis by generating circulating T-cell progenitors capable of homing to and developing within a human thymic graft. Surprisingly, development of CB stem cells in this in vivo model extended to elements of the endothelial cell lineage, which contributed to the revascularization of transplants and wound healing. These results demonstrate that human CB stem cell transplantation can reconstitute thymic-dependent T-cell lymphopoiesis and show a novel role of CB-derived hematopoietic stem cells in angiogenesis.

Cytokine response gene 6 induces p21 and regulates both cell growth and arrest

Cytokine response gene #6 (CR6), cloned from interleukin 2-stimulated T lymphocytes, is homologous to GADD45 and MyD118, genes which promote cell cycle arrest and apoptosis. To determine how this gene family could possibly mediate both cell survival/proliferation and cell cycle arrest/death, transfectants were generated so that the genes could be expressed ectopically, independently from their normal inducing agents. In cycling retinoblastoma protein-negative (pRb-) cells, ectopic CR6 expression blocked G2/M transition, but did not prevent G1/S transition so that endoreduplication resulted. By comparison, when CR6, GADD45, and MyD118 genes were expressed ectopically in proliferating pRb+ cells, either G1/S or G2/M transition was effectively blocked, so that there was no endoreduplication. Consistent with these findings, in proliferating pRb-cells, ectopic expression of CR6 promoted the expression of both G1 and G2/M cyclins. By comparison, in pRb+ cells, the expression of G1 cyclins was increased, while expression of the mitotic cyclins was decreased. However, in pRb+ cells, cyclin-dependent kinase activities associated with both G1 and G2/M cyclins were decreased. Moreover, ectopic expression of all three genes resulted in the expression of the CKI, p21, both in pRb- and pRb+ cells. The physiologic induction of CR6 expression by IL2 in quiescent normal human T cells occurs transiently in the first half of G1, coordinately with the expression of p21. Therefore, this gene family regulates G1 and G2, and promotes either cell growth or arrest by a common mechanism.

Restoration of immunity with interleukin-2 therapy

HIV replication can now be effectively suppressed using antiretroviral combination regimens. The search continues, however, for ways to restore the immune response and eliminate reservoirs of latent infection. Interleukin-2 (IL-2) may augment the immune response in HIV-infected persons. This article discusses the rationale for using IL-2 in those with HIV disease and reviews key trials of IL-2 treatment regimens.

PU.1 and the granulocyte- and macrophage colony-stimulating factor receptors play distinct roles in late-stage myeloid cell differentiation

PU.1 is a hematopoietic cell-specific ets family transcription factor. Gene disruption of PU.1 results in a cell autonomous defect in hematopoietic progenitor cells that manifests as abnormal myeloid and B-lymphoid development. Of the myeloid lineages, no mature macrophages develop, and the neutrophils that develop are aberrantly and incompletely matured. One of the documented abnormalities of PU. 1 null (deficient) hematopoietic cells is a failure to express receptors for granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, and M-CSF. To elucidate the roles of the myeloid growth factor receptors in myeloid cell differentiation, and to distinguish their role from that of PU.1, we have restored expression of the G- and M-CSF receptors in PU.1-deficient cells using retroviral vectors. We have similarly expressed PU.1 in these cells. Whereas expression of growth factor receptors merely allows a PU.1-deficient cell line to survive and grow in the relevant growth factor, expression of PU.1 enables the development of F4/80(+), Mac-1(+)/CD11b(+) macrophages, expression of gp91(phox) and generation of superoxide, and expression of secondary granule genes for neutrophil collagenase and gelatinase. These studies reinforce the idea that availability of PU.1 is crucial for normal myeloid development and clarify some of the molecular events in developing neutrophils and macrophages that are critically dependent on PU.1.

Development and evaluation of a direct immunofluorimetric assay for urinary growth hormone

We describe a two-site immunofluorimetric assay for urinary growth hormone that is resistant to interference from a wide range of urinary constituents and therefore eliminates the need for sample pre-treatment. A microtitre plate format is used with specific orientation of capture antibody on a polystyrene surface carrying a hydrazide group. Europium-labelled F(ab)2 is the fluorophore and time-resolved fluorimetry with co-fluorescence enhancement the signal detection system. Inter-assay precision was 11.3% at 5.2 ng/L and 10.3% at 44.3 ng/L, minimum detection limit (22% coefficient of variation, CV) was < 1.0 ng/L, working range (< 10% CV) was 0-100 ng/L and quantitative recovery and good parallelism were demonstrated. This convenient and sensitive assay is suitable for the routine measurement of human growth hormone (hGH) in urine.

Covariation of activity in habenula and dorsal raphé nuclei following tryptophan depletion

Abnormal serotonergic function is implicated in the pathogenesis of affective disorders. We induced transient depressive relapses in volunteer patients by rapidly depleting plasma tryptophan, the precursor of serotonin (5-HT), and measured neural activity during different cognitive tasks using positron emission tomography (PET). Neural activity in several 5-HT-related brain areas, e.g., dorsal raphé, habenula, septal region, amygdala, and orbitofrontal cortex, covaried significantly with plasma levels of tryptophan and ratings of depressed mood. Task-specific responses in left amygdala and left anterior cingulate were attenuated by tryptophan depletion. We used these PET data to test the hypothesis that projections from the habenula modulate dorsal raphé activity and that this modulation is enhanced in patients experiencing a profound mood change following serotonergic challenge. A strong linear correlation (r(2) > 0.5) between habenula and raphé activity was observed in subjects with postdepletion ratings >/=10 on a modified Hamilton depression scale, whereas subjects experiencing milder changes in mood had weaker habenula-raphé coupling (r(2) < 0.5). These data support a model of the serotonergic system in which the habenula projection to the raphé represents a convergent feedback pathway that controls the release of 5-HT throughout the brain. In our experiment we were able to engage this system in patients who were sensitive to tryptophan depletion.

Brain mechanisms associated with depressive relapse and associated cognitive impairment following acute tryptophan depletion

BACKGROUND

Acute tryptophan depletion lowers brain serotonin synthesis and results in a transient, but striking, clinical relapse in recovered depressed patients.

AIMS

To identify brain regions which change their activity as an acute depressive relapse evolves and to determine how pathological mood might modulate neural activity during a cognitive task.

METHOD

We used H2(15)O positron-emission tomography (PET) to study eight recovered depressed men after tryptophan depletion and after a control procedure. During both PET scan sessions, subjects performed a paced verbal fluency task which alternated with a control verbal repetition task.

RESULTS

Increasing levels of depression after tryptophan depletion were associated with diminished neural activity in the ventral anterior cingulate, orbitofrontal cortex and caudate nucleus regions. In addition, depressive relapse attenuated cognitive task-related activation in the anterior cingulate cortex.

CONCLUSIONS

Our data indicate that changes in neural activity in distinct brain regions mediate the clinical phenomena of depression and depression-related cognitive impairment following acute tryptophan depletion. These changes could be associated with the widespread distribution of serotonin neurons in brain pathways associated with the expression of affect and cognitive performance.