A mathematical model for storage and recall functions in plants

In plantlets of Bidens pilosa L., under severely limiting environmental conditions the growth of the buds at the axil of the cotyledons (cotyledonary buds) is asymmetric (i.e. one of the buds starts growing before the other one), this asymmetry being oriented by the pricking of one of the cotyledons (i.e. pricking one cotyledon increases the probability that the bud at the axil of the other cotyledon be the first to start to grow). As long as the plant apex (i.e. the terminal bud) is present, the growth of the cotyledonary buds is inhibited (apical dominance), but the souvenir of the asymmetric message caused by sub-optimal environmental conditions and the orientation given by the cotyledon pricking is always present in the plant and can be revealed by removing the apex. Depending on the conditions for removing the plant apex and/or on the application of a variety of symmetrical treatments (e.g. thermal treatment, symmetrical pricking treatments, etc.) the stored asymmetry will either take effect (the bud at the axil of the non-pricked cotyledon will be the first to start to grow more often than the other one) or not (both buds will have equal chance to be the first to start to grow). This has been termed 'recalling' the stored asymmetry. By combining several successive symmetrical treatments, it is possible to reversibly switch on and off the recall function several times. This recall of the stored plant-asymmetry is analogous to the evocation function of a memory system. In this paper, we will present first a discrete logical version of the observed interaction structure between the main components of the bud growth system, then a continuous differential version, taking into account the main features of the observed experimental reality and trying to explain this phenomenology. The interaction structure of both the discrete and the continuous models presents similar positive and negative feedback circuits, necessary condition for observing multistationarity and stability.

Who answers 'willingness to pay' questions?

OBJECTIVES

The objectives of this study were twofold. The first was to compare characteristics of responders and non-responders to a survey of women attending a bone mineral density screening service in Aberdeen concerned with the screening process which contained questions on attenders' willingness to pay (WTP) and willingness to wait (WTW) for screening. The second objective was to compare the characteristics of those responding to either the WTP or the WTW questions relative to those who responded to both.

METHODS

After receiving a scan, women completed the questionnaire at the clinic or returned it by post. Logistic regression analysis was used to compare the characteristics of the responders and non-responders.

RESULTS

Those who smoked were less likely to return the questionnaire, whilst those who drank alcohol were more likely to return it. The majority of respondents answered both WTP and WTW questions. The proportions responding to the WTW and WTP questions were 93.2% and 81.5% for the two questions, respectively (95% confidence interval of difference = 9.4% to 13.9%). The only result which was statistically significant at the 1% level showed that, relative to those who answered the WTW but not the WTP questions, those who answered both were more likely to be older when they left full-time education. A weaker statistical association (at the 5% level) revealed that those who were older when leaving full-time education were more likely to answer a WTP question than not.

CONCLUSIONS

WTP questions seem to be less acceptable to those who leave full-time education earlier. Analysts may need to account for this in future studies. Whether such results can be replicated and reasons for non-response should be investigated.

Positive feedback circuits and memory

The concept of regulatory feedback circuit refers to oriented cyclic interactions between elements of a system. There are two classes of circuits, positive and negative, whose properties are in striking contrast. Positive circuits are a prerequisite for the occurrence of multiple steady states (multistationarity), and hence, they are involved in all processes showing hysteresis or memory. Endogenous or exogenous perturbations can lead the system to exhibit or to evoke one particular stable regime. The role of positive circuits in cell differentiation and in immunology is well documented. Negative circuits are involved in homeostatic regulation, with or without oscillations. The aim of this paper is to show: a) that positive circuits account for many features of memory stricto sensu (i.e., neural memory and mnesic evocation) as well as largo sensu (e.g. differentiation or immunological memory); and b) that simple combinations of positive and negative circuits provide powerful regulatory modules, which can also be associated in batteries. These entities have vast dynamical possibilities in the field of neurobiology, as well as in the fields of differentiation and immunology. Here we consider a universal minimal regulatory module, for which we suggest to adopt the term 'logical regulon', which can be considered as an atom of Jacob's integron. It comprises a positive and a negative circuit in its interaction matrix, and we recall the main results related to the simultaneous presence of these circuits. Finally, we give three applications of this type of interaction matrix. The first two deal with the coexistence of multiple stable steady states and periodicity in differentiation and in an immunological system showing hysteretic properties. The third deals with the dual problems of synchronization and desynchronization of a neural model for hippocampus memory evocation processes.

Percutaneous ablation of caliceal diverticulum: long-term followup

PURPOSE

A caliceal diverticulum is a nonsecretory cavity that serves as a conduit for urinary stasis and its ensuing complications. Indications for intervention and modes of therapy are controversial. We report a series of patients treated with a percutaneous endourological approach to ablation of the diverticular cavity.

MATERIALS AND METHODS

A total of 14 patients underwent percutaneous ablation of a caliceal diverticulum for flank pain a mean of 15.5 months in duration. These caliceal diverticula were associated with urinary tract infection in 43% of cases and/or renal calculi in 78%. Mean calculus diameter was 10.2 mm. and mean diverticular diameter was 10.9 mm. An open ended ureteral catheter was placed into the renal pelvis via cystoscopy. Retrograde instillation of radiopaque contrast medium facilitated the localization of a percutaneous renal puncture made directly into the caliceal diverticulum. A flexible tip guide wire was coiled in the diverticulum, and no effort was made to traverse the infundibulum and establish continuity with the remainder of the collecting system. Tract dilation into the caliceal diverticulum was performed, and percutaneous stone fragmentation and extraction were accomplished. The lining of the caliceal diverticulum was electrocauterized using a roller ball electrode. A balloon nephrostomy tube consisting of a Foley catheter with the tip cut off was positioned into the diverticulum. An indwelling ureteral stent was placed and a Foley catheter provided bladder drainage for 48 hours to maintain a low pressure system. The nephrostomy tube was removed after 24 to 48 hours and the ureteral stent was removed after 2 to 4 weeks.

RESULTS

Mean operative time was 162 minutes and mean hospital stay was 2.3 days. Obliteration of the diverticular infundibulum and cavity was documented by contrast radiography (excretory urography or retrograde pyelography), and noncontrast and contrast enhanced computerized tomography, respectively, in all 14 patients. No patients have had recurrent symptoms, calculi or urinary tract infection at a mean 38-month followup.

CONCLUSIONS

Percutaneous electrocautery ablation of caliceal diverticula without cannulation or dilation of the diverticular infundibulum represents a safe and effective mode of therapy. Careful patient selection and preparation optimize the efficacy of this technique.

Effects of azide on the S(2) state EPR signals from Photosystem II

The anion azide, N(3) (-), has been previously found to be an inhibitor of oxygen evolution by Photosystem II (PS II) of higher plants. With respect to chloride activation, azide acts primarily as a competitive inhibitor but uncompetitive inhibition also occurs [Haddy A, Hatchell JA, Kimel RA and Thomas R (1999) Biochemistry 38: 6104-6110]. In this study, the effects of azide on PS II-enriched thylakoid membranes were characterized by electron paramagnetic resonance (EPR) spectroscopy. Azide showed two distinguishable effects on the S(2) state EPR signals. In the presence of chloride, which prevented competitive binding, azide suppressed the formation of the multiline and g = 4.1 signals concurrently, indicating that the normal S(2) state was not reached. Signal suppression showed an azide concentration dependence that correlated with the fraction of PS II centers calculated to bind azide at the uncompetitive site, based on the previously determined inhibition constant. No evidence was found for an effect of azide on the Fe(II)Q(A) (-) signals at the concentrations used. This result is consistent with placement of the uncompetitive site on the donor side of PS II as suggested in the previous study. In chloride-depleted PS II-enriched membranes azide and fluoride showed similar effects on the S(2) state EPR signals, including a notable increase and narrowing of the g = 4.1 signal. Comparable effects of other anions have been described previously and apparently take place through the chloride-competitive site. The two azide binding sites described here correlate with the results of other studies of Lewis base inhibitors.

Ibuprofen use to reduce the incidence and severity of bronchopulmonary dysplasia: a pilot study

OBJECTIVE

To assess the safety and efficacy of ibuprofen in reducing the incidence and severity of bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

A total of 18 premature infants between 23 and 28 weeks' gestation were studied. Ibuprofen (10 mg/kg of loading dose followed by 5 mg/kg every 12 hours) was administered intravenously or orally to nine infants on respiratory support at > or = 7 days of age and was continued until 28 days of life or until the infants were spontaneously breathing room air, whichever occurred earlier. Ibuprofen levels in plasma were measured in five of these infants. The outcome variables (BPD, ventilatory parameters, and complications) in the study group were compared with those in nine matched controls treated conventionally.

RESULTS

The incidence of BPD at 36 weeks postconceptional age was similar in both groups (eight of nine in each group). The percentage of oxygen requirement, the ventilatory efficiency index, and steroid use were also similar in both groups. One infant in the study group, who was also receiving steroids and aminophylline, developed gastrointestinal hemorrhage. Reversible renal failure in one infant and necrotizing enterocolitis in another infant were seen at 4 and 21 days, respectively, after the last dose of ibuprofen. There was no difference in the incidence of intraventricular hemorrhage between the two groups. Plasma levels of ibuprofen at 3 hours after the first dose ranged from 10.3 to 36 mg/liter. Study infants tolerated the feeds better and achieved the full enteral goal earlier than controls (p = 0.04).

CONCLUSION

Although a trend toward less ventilator and hospital days in the ibuprofen group was observed in this pilot study, the differences were not statistically significant. The incidence of BPD was similar in both groups. In the study group, two infants developed gastrointestinal complications and a third infant experienced reversible renal failure. The plasma ibuprofen levels were low. Further studies are needed to assess the use of ibuprofen for the prevention and/or treatment of BPD in preterm infants.

Acute toxicity assessment of Polish (waste) water with a microplate-based Hydra attenuata assay: a comparison with the Microtox test

The use of Hydra attenuata in acute toxicity assessment is a potentially useful tool in (waste) water biomonitoring. The purpose of this study was to compare the sensitivity of H. attenuata with the extensively used Microtox test on 14 (waste) water samples from the Kraków region (South Poland). To this end, specific morphological changes displayed by the freshwater cnidarian Hydra attenuata (lethal LC50s and sublethal EC50s effects) and bioluminescence of the marine bacteria Vibrio fisheri (Microtox) were compared. Clearly, the Hydra assay was the more sensitive indicator of toxicity. No relationship was found among Hydra toxicological responses and water levels of As, Cd, Co, Cu, Pb and Zn. However, it appeared that toxicity to Hydra might be due to ammonia levels. Additional studies to better circumscribe the tolerance of H. attenuata to 'natural' water characteristics are needed.

Silent functional magnetic resonance imaging demonstrates focal activation in rapid eye movement sleep

Functional imaging of human sleep has been performed with nuclear medicine methods, but MRI has been difficult to implement, in part because of the noise associated with echo-planar imaging as well as the difficulty in reading physiologic signals in the MRI environment. We describe a silent MR sequence that can record brain activation over many hours with simultaneous acquisition of an EEG. This shows activation of occipital cortex and deactivation of frontal cortex during REM sleep, in agreement with previous studies using other techniques. MRI-Sleep-REM sleep.

Neurochemical markers do not correlate with cognitive decline in the Lewy body variant of Alzheimer disease

BACKGROUND

Reductions in neocortical synapses and cholinergic function occur in patients with Alzheimer disease (AD) and in patients with the Lewy body variant of AD (LBV). The relation between these losses and cognitive decline has been reported frequently in patients with AD but remains unclear for patients with LBV.

OBJECTIVES

To investigate the relation between clinical markers of disease progression and choline acetyltransferase activity or synaptic density, measured by synaptophysin (Syn) level, in patients with LBV, and to investigate the relation of these neurochemical markers with one another.

METHODS

Brain specimens of 41 patients with autopsy-confirmed (National Institute on Aging criteria for AD) LBV were examined. The last Mini-Mental State Examination and Blessed Information-Memory-Concentration test scores before death were reviewed. Midfrontal synapse counts were quantified by a dot-immunobinding assay for Syn. Choline acetyltransferase activity of the midfrontal cortex was assayed by established protocols.

RESULTS

The last Mini-Mental State Examination score before death did not correlate significantly with Syn level (n = 25, r = 0.25, P = .24); however, there was a trend toward significance for the relation between last Mini-Mental State Examination score and choline acetyltransferase activity (n = 39, r = 0.31, P = .05). The last Blessed Information-Memory-Concentration test score did not correlate with either Syn level (n = 24, r = -0.17, P = .44) or choline acetyltransferase activity (n = 39, r = -0.16, P = .33). Finally, there was only a modest correlation between Syn level and choline acetyltransferase activity (n = 25, r = 0.38, P = .06), which did not reach statistical significance.

CONCLUSION

Unlike AD, neurochemical markers do not appear to correlate well with cognitive decline in LBV.

Evaluating supervised HAART in late-stage HIV among drug users: a preliminary report

OBJECTIVE

To examine response to highly active antiretroviral therapy (HAART) among a sample of treatment-experienced patients in the late stage of human immunodeficiency virus (HIV) infection in residential health care facilities (RHCFs) in New York City facilities designated for HIV/AIDS (acquired immunodeficiency syndrome) when access and adherence are maximized.

METHODS

Medical record review of 111 patients.

RESULTS

Demographics were mean age 42 years; 58% male; 60% African-American; 31% Hispanic; 57% injection drug users (IDUs); 23% with history of dementia; 52% hepatitis C virus (HCV) antibody seropositive; 80% on HAART, of whom 18% had lipodystrophy. Of 88 patients on HAART, 52% had a decreased viral load (>1/2 log) versus 13% of 23 not on HAART (P<.05); a >1/2 log viral load increase was seen in 8% and 35%, respectively (P<.05). Those with viral load increase were more likely than those with stable/decreased viral load to be IDUs (71% vs. 64%) and to have HCV seropositivity (86% vs. 53%), even with similar initial CD4+ cell count, viral load, and follow-up time.

CONCLUSION

In a predominantly minority IDU population who are treatment experienced, 50% of the patients successfully responded to treatment with supervised therapy. The RHCFs in New York City provide a unique opportunity to examine further factors associated with response to HAART in an environment in which medication administration and adherence are maximized and monitored carefully.

Coordinated maturational regulation of PHEX and renal phosphate transport inhibitory activity: evidence for the pathophysiological role of PHEX in X-linked hypophosphatemia

The mechanism by which inactivating mutations of PHEX (phosphate-regulating gene with homologies to endopeptidases on the X chromosome) cause X-linked hypophosphatemia remains unknown. However, recent reports suggest errant PHEX activity in osteoblasts may fail to inactivate a phosphaturic factor produced by these cells. To test this possibility, we examined coordinated maturational expression of PHEX and production of phosphate transport inhibitory activity in osteoblasts from normal and hyp-mice. We assessed the inhibitory activity in conditioned medium by examining the effects on opossum kidney cell phosphate transport and osteoblast PHEX expression by reverse transcriptase-polymerase chain reaction during a 17-day maturational period. Inhibitory activity increased as a function of osteoblast maturational stage, with no activity after 3 days and persistent activity by 6 days of culture. More significantly, equal phosphate transport inhibitory activity in conditioned medium from normal and hyp-mouse osteoblasts (control 1.90 +/- 0.12, normal 1.48 +/- 0.10, hyp 1.45 +/- 0.04 nmol/mg of protein/minute) was observed at 6 days. However, by 10 days hyp-mouse osteoblasts exhibited greater inhibitory activity than controls, and by 17 days the difference in phosphate transport inhibition maximized (control 2.08 +/- 0.09, normal 1.88 +/- 0.06, hyp 1.58 +/- 0.06 nmol/mg of protein/minute). Concurrently, we observed absent PHEX expression in normal osteoblasts after 3 days, limited production at 6 days, and significant production by day 10 of culture, while hyp-mouse osteoblasts exhibited limited PHEX activity secondary to an inactivating mutation. The data suggest that the presence of inactivating PHEX mutations results in the enhanced renal phosphate transport inhibitory activity exhibited by hyp-mouse osteoblasts.

A randomized, prospective study to evaluate the efficacy and acceptance of three bowel preparations for colonoscopy in children

OBJECTIVE

We performed a prospective, randomized, single-blind study in children undergoing colonoscopy to evaluate the acceptance and efficacy of three different bowel preparations.

METHODS

Seventy patients (ages 3-20 yr, 38 males) were randomly assigned to one of the three study preparations: Magnesium citrate with X-prep and clear liquid diet for 2 days (group A); Dulcolax for 2 days and Fleet enema without dietary restriction (group B); and Golytely 20 ml/kg (up to 1 L) per hour for 4 h with clear liquid diet for 1 day (group C). Endoscopists blinded to bowel preparation graded the adequacy of colon cleansing. The preparations were rated by patients for tolerance, willingness to retake them, adverse effects, and compliance.

RESULTS

Data analysis using Fisher exact test and trend test showed that colon cleansing in groups A and C was superior to that in group B (p < 0.0001) and better in group C than A (p < 0.075). Overall tolerance and compliance were significantly better for groups A and B than group C (p < 0.003), but not different between A and B. More of group B patients were willing to retake the preparation than in group C (p < 0.002) and group A (p < 0.05), but this was not different between groups A and C. Adverse effects were reported more frequently by patients in group C than in groups A and B (p < 0.01).

CONCLUSIONS

Although the least well tolerated, Golytely provided the best cleansing. Dulcolax without dietary restriction provided unsatisfactory colon cleansing. Magnesium citrate with X-prep was acceptable and provided good cleansing.

Resistance of rheumatoid synovial dendritic cells to the immunosuppressive effects of IL-10

IL-10 down-regulates the APC function of many dendritic cells (DC), including human peripheral blood (PB) DC. In rheumatoid arthritis (RA), synovial fluid (SF) DC express markers of differentiation and are effective APC despite abundant synovial IL-10. The regulation of DC responsiveness to IL-10 was therefore examined by comparing the effect of IL-10 on normal PB and RA SF DC. Whereas IL-10 down-modulated APC function and MHC class II and B7 expression of PB DC, IL-10 had no such effect on SF DC. Since SF DC have differentiated in vivo in the presence of proinflammatory cytokines, PB DC were cocultured in the presence of IL-10 and either GM-CSF, IL-1beta, TNF-alpha, IL-6, or TGF-beta. GM-CSF, IL-1beta, and TNF-alpha were all able to restore APC function. Whereas the effects of IL-10 on PB DC were shown to be mediated by IL-10R1, neither PB nor RA SF DC constitutively expressed IL-10R1 mRNA or detectable surface protein. In contrast, IL-10R1 protein was demonstrated in PB and SF DC whole cell lysates, suggestive of predominant intracellular localization of the receptor. Thus, DC responsiveness to IL-10 may be regulated through modulation of cell surface IL-10R1 expression or signaling.

Incidence of immediate and delayed hypersensitivity to Centruroides antivenom

STUDY OBJECTIVE

To assess the incidence and course of immediate and delayed hypersensitivity to Centruroides antivenom.

METHODS

We performed a 12-month prospective observation study, with telephone follow-up, evaluating the incidence of anaphylaxis or anaphylactoid reactions and serum sickness after Centruroides antivenom administration. The setting for the study was a poison control center and tertiary care toxicology treatment center. Participants included all patients who received Centruroides antivenom, and no interventions were performed.

RESULTS

For immediate hypersensitivity reactions, 116 patients with grade III or IV envenomation received Centruroides antivenom; 77 of these patients were younger than 13 years. Three patients completed the infusion despite development of rash. A fourth patient with a history of atopy and asthma received epinephrine infusion and an inhaled beta-agonist for transient wheezing that quickly resolved; she was admitted for observation. Nine patients without hypersensitivity reactions were admitted for social reasons, for inappropriate sedation from drugs used before antivenom, or to rule out aspiration; all were discharged within 24 hours. The remaining 106 patients were discharged from the emergency department after resolution of symptoms. Thus 4 of 116 patients had immediate reactions. For patients with delayed reactions, 17 patients were lost to follow-up. Of 99 remaining patients, serum sickness developed in 61% (n=60), as defined by using liberal criteria. Serum sickness responded to oral steroids, antihistamines, or both; mean duration of symptoms with medication was 2.8 days.

CONCLUSION

Anaphylactic reactions are uncommon after Centruroides antivenom infusion. Self-limited serum sickness that is easily controlled with corticosteroids and antihistamines commonly follows the use of Centruroides antivenom.

Acute mitral valve regurgitation created in sheep using echocardiographic guidance

BACKGROUND AND AIM OF STUDY

This study was designed to determine: (i) Whether acute mitral valve regurgitation (MVR) due to chordal rupture can be reproducibly created under echocardiographic guidance; (ii) what degree of MVR can be created; (iii) what degree of acute regurgitation is survivable; and (iv) whether acute MVR due to chordal rupture progresses over time.

METHODS

In a pilot group of six juvenile farm-bred sheep, selected chordae tendineae were ruptured using either a biopsy needle or endoscopic scissors under echocardiographic guidance, without need for cardiopulmonary bypass. Sheep were sacrificed acutely (n = 2), and at six weeks (n = 2) or eight weeks (n = 2). When the technique was optimized, five sheep entered a study group in which chords were ruptured using endoscopic scissors; the sheep were sacrificed 16 weeks after surgery.

RESULTS

In the pilot study, acute MVR (grade 2-4+) was produced in all sheep, normal ventricular wall motion was maintained, with minimal progression of regurgitation over time. In one pilot sheep which did not survive, grade 4+ MVR was created acutely. Use of endoscopic scissors was preferable to the biopsy needle. In the study group, acute MVR (grade 2-4+) was produced in all five sheep, and was still present at 16 weeks, with progression in only one animal.

CONCLUSIONS

This pilot study demonstrated that controlled degrees of survivable acute MVR due to chordal rupture can be created under echocardiographic guidance, with minimal progression of MVR over time. This animal model can be applied to investigate the pathogenesis of clinical MVR, and to suggest appropriate medical or surgical intervention.

1998 American Urological Association Gallup Survey: changes in physician practice patterns, treatment of ureteral stones and impact of managed care

PURPOSE

The American Urological Association first commissioned the Gallup Organization to conduct a study to assess urologist practice patterns in 1992. We present the results of the seventh consecutive Gallup Survey performed for the Association.

MATERIALS AND METHODS

A random sample of 537 American urologists who completed urological residency and practiced at least 20 hours weekly in 1997 were interviewed by telephone in March 1998. Major topic areas included general demographics, practice patterns, treatment of ureteral stones and experience with managed care.

RESULTS

Demographic trends indicated a significant decrease in average urologist age from 49.4 years in 1992 to 46.8 in 1998. Of the urologists 99% reported that they treat ureteral stones. Managed care had an increasingly larger role in most practices, particularly in the western United States, where 73% of urologists reported that they contract with a Medicare health maintenance organization.

CONCLUSIONS

The average age of practicing urologists significantly decreased, which may be due to an increasing number of urologists retiring at an earlier age, although this finding is not clear. Nearly all urologists treated ureteral stones with considerable consistency. Finally, managed care appeared to have a major impact on most urologists throughout the United States.

Carbon monoxide poisoning and hyperbaric oxygen

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Reciprocal chromosome painting reveals detailed regions of conserved synteny between the karyotypes of the domestic dog (Canis familiaris) and human

The domestic dog is increasingly being recognized as a useful model for human disease. The aim of this study was to conduct the first detailed whole-genome comparison of human and dog using bidirectional heterologous chromosome painting (reciprocal Zoo-FISH) analysis. We used whole-chromosome paint probes produced from degenerate oligonucleotide-primed PCR amplification of high-resolution bivariate flow-sorted human and dog chromosomes. No fewer than 68 evolutionarily conserved segments were identified between the dog and the human karyotypes. The use of elongated metaphase chromosomes for both species allowed the boundaries of each evolutionarily conserved segment to be determined to subband resolution. The distribution of conserved segments is discussed, as are the applications of these data in refining the current status of the dog genome map.

Dendritic cells: the driving force behind autoimmunity in rheumatoid arthritis?

Dendritic cells (DC) are likely to play a significant role in immune-mediated diseases such as autoimmunity and allergy. To date there are few treatments capable of inducing permanent remission in rheumatoid arthritis (RA) and elucidation of the role of DC may provide specific strategies for disease intervention. Dendritic cells have proven to be powerful tools for immunotherapy and investigations are under way to determine their clinical efficacy in transplantation and viral and tumour immunotherapy. The present review will focus on the current view of DC and their role in autoimmunity, in particular RA. Two possible roles for DC in the pathogenesis of RA will be proposed, based on recent advances in the field.

Immature human monocyte-derived dendritic cells migrate rapidly to draining lymph nodes after intradermal injection for melanoma immunotherapy

Injected antigen-loaded immature monocyte-derived dendritic cells (DCs) may be incapable of migrating from skin to draining lymph nodes for antigen presentation. The in vivo migratory capacity of intradermally administered immature monocyte-derived DCs was therefore investigated during a phase I/II clinical trial for metastatic melanoma. DCs cultured from adherent monocytes in the presence of autologous serum, granulocyte-macrophage colony stimulating factor and interleukin-4 were pulsed with antigen and labelled with technetium-99m hexamethylpropylene-amineoxime (99mTc-HMPAO) ex vivo, then injected intradermally. A 99mTc-HMPAO control containing an equivalent amount of radioactivity was injected into the opposite thigh. The pelvis was then imaged with a gamma camera. The DCs were characterized as immature by functional and phenotypic analysis. Labelled DCs travelled to the draining inguinal lymph nodes within 10 min, and the draining lymph nodes were clearly outlined up to 4 h after injection. Free NmTc outlined draining lymph nodes after 10 min but was cleared from the nodes within 1 h. Thus, immature human monocyte-derived DCs migrate rapidly to and remain in draining lymph nodes after intradermal injection for immunotherapy.