Perceptions of telemedicine at a pediatric otolaryngology-head and neck surgery program

Objective

With few studies investigating the effectiveness of telemedicine (TM) in pediatric otolaryngology (ear, nose, and throat; ENT), its role in clinical practice is unclear. The objective of this study was to investigate provider perspectives regarding utility of TM in pediatric ENT practice.

Methods

A survey gauging the relative merits of TM visits for common pediatric ENT chief complaints and postoperative visits was distributed to all pediatric ENT providers at a tertiary care, free-standing children’s hospital. Respondents were asked to assess the effectiveness of TM visits compared with in-person visits for completing the following tasks: history collection, physical examination, medical decision-making, and patient counseling.

Results

Providers rated TM visits as less useful than in-person visits for completing the most predefined tasks but did identify advantages in history taking via TM for the majority of complaints. Compared with providers with ≥10 years of experience, those with <10 years of experience found TM to be more effective than the in-person appointment for making clinical decisions for patients presenting with recurrent/chronic pharyngitis, neck masses, and stridor/noisy breathing. Opinions regarding the utility of TM for postoperative visits were mixed, with adenoidectomy, tonsillectomy and superficial procedures being most frequently deemed appropriate for TM.

Conclusions

The introduction of TM to pediatric ENT faces limitations in detailed examination of areas not accessible without specialized instrumentation. Due to its strength in history taking, results suggest an asynchronous, ‘store and forward’ encounter followed by an in-person physical examination to confirm the diagnosis and treatment plan could be beneficial.

Saccular aneurysm of the iliofemoral vein: an uncommon mimic of an occult inguinal hernia

A 72-year-old man presented to clinic with a 1-week history of worsening groin pain. He had a normal hip examination and tenderness worsened with valsalva, but no mass palpated in the inguinal region. He was found to have a large saccular aneurysm of the iliofemoral vein on ultrasound and subsequently started on anticoagulation and referred to vascular surgery.

State of telemedicine use in pediatric surgery in the USA—where we stand and what we can gain from the COVID-19 pandemic: a scoping review

Background

Within the last decade, the use of telemedicine within in primary care in the USA has greatly expanded; however, use remains uncommon in surgical specialties. The spread of Coronavirus disease 2019 (COVID-19) prompted healthcare institutions to limit in-person contact, resulting in an increase in telemedicine across all specialties, including pediatric surgery. The aims of this review were to evaluate potential barriers that limited the use of telemedicine in pediatric surgery prior to the COVID-19 period and to define how best to incorporate its use into a pediatric surgical practice going forward.

Methods

A scoping review was performed to identify gaps in the literature pertaining to the use of telemedicine within general pediatric surgery in the USA prior to the outbreak of COVID-19. Next, a focused evaluation of the legislative and organizational policies on telemedicine was performed. Lastly, findings were summarized and recommendations for future research developed in the context of understanding and overcoming barriers that have plagued widespread adoption in the past.

Results

Despite evidence of telemedicine being safe and well received by adult surgical patients, a total of only three studies representing original research on the use of telemedicine within pediatric surgery were identified. Legislative and organizational policies regarding telemedicine have been altered in response to COVID-19, likely resulting in an increase in the use of telemedicine among pediatric surgeons.

Conclusions

Telemedicine offers a safe and effective option for patients seeking an alternative to the in-person clinic appointment. The increased utilization of telemedicine during the COVID-19 pandemic will provide an opportunity to learn how best to leverage the technology to decrease disparities and to overcome previous barriers.

The Need for Accurate Risk Assessment in a High-Risk Patient Population: A NSQIP Study Evaluating Outcomes of Cholecystectomy in the Patient With Cancer

BACKGROUND

Cholecystectomy is considered a low-risk procedure with proven safety in many high-risk patient populations. However, the risk of cholecystectomy in patients with active cancer has not been established.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was queried to identify all patients with disseminated cancer who underwent cholecystectomy from 2005 to 2016. Postcholecystectomy outcomes were defined for patients with cancer and those without by comparing several outcomes measures. A multivariate model was used to estimate the odds of 30-d mortality.

RESULTS

We compared outcomes in 3097 patients with disseminated cancer to a matched cohort of patients without cancer. Patients with cancer had more comorbidities at baseline: dyspnea (10.5% versus 7.0%, P < 0.0001), steroid use (10.1% versus 3.0%, P < 0.0001), and loss of >10% body weight in 6-mo prior (9.3% versus 1.6%, P < 0.0001). Patients with cancer sustained higher rates of wound (2.3% versus 5.6%, P < 0.0001), respiratory (1.4% versus 3.9%, P < 0.0001), and cardiovascular (2.0% versus 6.8%, P < 0.0001) complications. In addition, patients with disseminated cancer experienced a longer length of stay and higher 30-d mortality. Multivariate modeling showed that the odds of 30-d mortality was 3.3 times greater in patients with cancer.

CONCLUSIONS

Compared to patients without cancer, those with disseminated cancer are at higher risk of complication and mortality following cholecystectomy. Traditional treatment algorithms should be used with caution and care decisions individualized based on the patient's disease status and treatment goals.

Introduction of the snake antenna array: Geometry optimization of a sinusoidal dipole antenna for 10.5T body imaging with lower peak SAR

Purpose

To improve imaging performance for body MRI with a local transmit array at 10.5T, the geometry of a dipole antenna was optimized to achieve lower peak specific absorption rate (SAR) levels and a more uniform transmit profile.

Methods

Electromagnetic simulations on a phantom were used to evaluate the SAR and B1+‐performance of different dipole antenna geometries. The best performing antenna (the snake antenna) was simulated on human models in a 12‐channel array configuration for safety assessment and for comparison to a previous antenna design. This 12‐channel array was constructed after which electromagnetic simulations were validated by B1+‐maps and temperature measurements. After obtaining approval by the Food and Drug Administration to scan with the snake antenna array, in vivo imaging was performed on 2 volunteers.

Results

Simulation results on a phantom indicate a lower SAR and a higher transmit efficiency for the snake antenna compared to the fractionated dipole array. Similar results are found on a human body model: when comparing the trade‐off between uniformity and peak SAR, the snake antenna performs better for all imaging targets. Simulations and measurements are in good agreement. Preliminary imaging result were acquired in 2 volunteers with the 12‐channel snake antenna array.

Conclusion

By optimizing the geometry of a dipole antenna, peak SAR levels were lowered while achieving a more uniform transmit field as demonstrated in simulations on a phantom and a human body model. The array was constructed, validated, and successfully used to image 2 individuals at 10.5T.

Leukotrienes in patients with clinically active multiple sclerosis

OBJECTIVES

The role of leukotrienes (LTs) in the pathophysiology of multiple sclerosis (MS) has been controversially discussed in the past. Studies of LTs in the cerebrospinal fluid (CSF) revealed different results mainly because of analytical difficulties.

MATERIAL AND METHODS

In the present study we used highly sensitive and specific analytical methods for measuring LTs in the CSF as well as in urine samples from 20 patients with active MS and 20 control patients with noninflammatory neurological disorders.

RESULTS

LTB4 concentrations in CSF were almost twice as high in MS patients compared with controls (P < 0.001). CSF concentrations of the cysteinyl-LTs (LTC4, LTD4 and LTE4) as well as urinary LTE4 showed no significant differences compared with controls (P > 0.05). In addition, there was no significant association between CSF pleocytosis, clinical severity or time of disease onset.

CONCLUSIONS

The increased concentration of LTB4 in the CSF of MS patients may indicate a biological importance for this mediator in MS.

Cytotoxic synergism of methioninase in combination with 5-fluorouracil and folinic acid

Potentiation of the cytotoxic activity of 5-fluorouracil (FUra) by folinic acid (5-HCO-H4folate) is due to elevation of the methylene tetrahydrofolate (CH2-H4folate) level, which increases the stability of the ternary complex of thymidylate synthase (TS), fluorodeoxyuridine monophosphate, and CH2-H4folate that inactivates the TS. Methionine deprivation results in the production of tetrahydrofolate (H4folate) and, subsequently, CH2-H4folate from methyl tetrahydrofolate, as a consequence of the induction of methionine synthesis. We hypothesized that the efficacy of FUra could be augmented by the combination of high-concentration 5-HCO-H4folate and recombinant methioninase (rMETase), a methionine-cleaving enzyme. Studies in vitro were performed with the cell line CCRF-CEM. Cytotoxic synergism of FUra + rMETase and FUra + 5-HCO-H4folate + rMETase was demonstrated with the combination index throughout a broad concentration range of FUra and rMETase. A subcytotoxic concentration of rMETase reduced the IC50 of FUra by a factor of 3.6, and by a factor of 7.5, in the absence and in the presence of 5-HCO-H4folate, respectively. 5-HCO-H4folate increased the intracellular concentrations of CH2-H4folate and H4folate from their baseline levels. Concentrations of folates were not changed by exposure to rMETase. Levels of free TS in cells treated with FUra + 5-HCO-H4folate and with FUra + rMETase were lower than those in cells exposed to FUra alone. The decrease of TS was still more pronounced in cells treated with FUra + 5-HCO-H4folate + rMETase. The synergism described in this study will be a basis for further exploration of combinations of fluoropyrimidines, folates, and rMETase.

[Interventions in carotid stenoses: carotid srugery, percutaneous transluminal balloon angioplasty and stent implantation. Indications, results of clinical studies. An overview]

Ischemic stroke is the third most reason of death and the main reason of severe disability in Western countries. The high incidence of stroke, 330 per 100,000 subjects in Germany, illustrates the importance of the disease. Generally, atherosclerotic stenosis of the proximal internal carotid artery is the responsible mechanism. The clinical efficiency of surgically performed endarterectomy has been demonstrated in several large multicenter trials. Proven indications for endarterectomy are symptomatic moderate to high-grade stenoses, rapidly progressive asymptomatic stenoses and asymptomatic patients with lesions revealing greater than sixty percent diameter stenosis under certain clinical conditions. Reduction of the incidence of cerebrovascular events, though, is only possible if a low perioperative complication rate is accomplished. Recommendations of the American Heart Association demand a total periprocedural complication rate less than six percent for symptomatic and less than three percent for asymptomatic stenoses. Implantation of stents in carotid arteries is a promising method which might expand the spectrum of indications toward stenosis morphology unfavorable for surgery and patients with significant comorbidity. Clinical results reveal primary success rates, complication rates, and restenosis rates comparable with those of surgical endarterectomy. Randomized trials, comparing both methods, are necessary and reasonable. Yet results are not available at the moment.

Relationship of atypical melatonin rhythm with two circadian clock outputs in B6D2F(1) mice

Circadian rhythms in body temperature, locomotor activity, and the circadian changes of plasma and pineal melatonin content were investigated in B6D2F(1) mice synchronized by 12 h of light and 12 h of darkness. During 8 wk continuous recording, activity and temperature displayed a marked stable and reproducible circadian rhythm, with both peaks occurring near the middle of darkness. Both 24- and 12-h rhythmic components were also significantly detected. Mean plasma melatonin concentration rose steadily during the light span and reached a maximum (30.6 +/- 10.0 pg/ml) at 11 h after light onset (HALO), then gradually decreased after the onset of darkness to a nadir (4.7 +/- 0.4 pg/ml) at 20 HALO. Mean pineal content followed a pattern parallel to that of plasma concentration (peak at 11 HALO: 17.7 +/- 1.0 pg/gland; trough at 17 HALO: 4.7 +/- 1.0 pg/gland). In addition, a second sharp peak was observed at 21 HALO (20.2 +/- 3.5 pg/gland). Plasma and pineal contents displayed large and statistically significant circadian changes, with a composite rhythm of period (24 + 12 h). This mouse model has predominant production and secretion of melatonin during the day. This possibly contributes to a similar coupling between chronopharmacology mechanisms and the rest-activity cycle in these mice and in human subjects.

Oxaliplatin: pharmacokinetics and chronopharmacological aspects

Oxaliplatin is the first clinically available diaminocyclohexane platinum coordination complex. The drug is non-cross-resistant with cisplatin or carboplatin and is one of the few active drugs against human colorectal cancer. Its cytotoxicity is synergistic with fluorouracil and folinic acid (leucovorin), the reference treatment for this disease. The main cumulative dose-limiting toxicity of oxaliplatin is peripheral sensory neuropathy. The drug can also produce diarrhoea, vomiting and haematological suppression. Unlike cisplatin, no renal failure or peripheral motor neuropathy have been reported and the sensory neuropathy is partly reversible. Unlike carboplatin, oxaliplatin produces only mild to moderate haematological toxicity. Oxaliplatin undergoes biotransformation into aquated forms in the blood, where 3 species can be found: total platinum, ultrafilterable or 'free' platinum and erythrocyte platinum. Flameless atomic absorption (FAAS) is used for assaying platinum concentration in various tissues. Inductively-coupled plasma mass spectrometry (ICP-MS), with a >10-fold lower sensitivity threshold than FAAS, was also used for the determination of oxaliplatin pharmacokinetics. The pharmacokinetics of oxaliplatin are described by a 3-compartment model. The drug rapidly crosses the cellular membrane as a result of its lipophilicity. Hence, at the end of a 2-hour infusion, approximately 40% of the blood platinum is found in erythrocytes. The distribution half-life of ultrafiltrated plasma platinum ranges from 10 to 25 minutes and its terminal elimination half-life is 26 hours (determined with FAAS) or 270 hours (ICP-MS). The elimination half-life of erythrocytic platinum is 12 to 50 days, close to that of erythrocytes. 30 to 50% of the platinum is recovered in the urine within 2 to 5 days, with renal clearance accounting for half of the total clearance of ultrafiltrated platinum. The total clearance of this species is correlated with the glomerular filtration rate. No pharmacokinetic-pharmacodynamic relationship has been established for oxaliplatin. Pharmacokinetic alterations produced by fluorouracil + folinic acid or irinotecan were minimal if any. The prolonged stability of oxaliplatin makes it suitable for continuous infusions over 4 to 5 days, with a delivery rate which can be either constant or chronomodulated (peak rate at 1600h), using programmable ambulatory pumps. Chronomodulation significantly reduces toxicity and improves antitumour activity as compared with constant rate infusion. These differences in pharmacodynamic properties were paralleled by differences in plasma concentration time courses. The different drug concentration profiles achieved with different infusional modalities may be useful tools for understanding the relationship between the pharmacokinetics and pharmacodynamics of oxaliplatin and may lead to further optimisation of its administration schedule and its combination with other drugs.

[Calcifying aortic valve stenosis and occult gastrointestinal hemorrhage (Heyde syndrome): description of 2 cases]

The coincidence of aortic valve stenosis and cryptogenic gastrointestinal bleeding usually from angiodysplasia of the cecum and ascending colon has been called Heyde syndrome. The pathophysiologic link between both remains unclear and may be due to subtle changes in plasmatic coagulation. There are some statistic and numerous casuistic reports, and recently the existence of the syndrome has been questioned. We describe two cases of aortic valve stenosis and cryogenic gastrointestinal bleeding in which bleeding subsided after replacement with a bioprosthesis. We give an overview of the current literature.

A hybrid technique for spectroscopic imaging with reduced truncation artifact

Traditionally, Fourier spectroscopic imaging is associated with a small k-space coverage which leads to truncation artifacts such as "bleeding" and ringing in the resultant image. Because substantial truncation artifacts mainly arise from regions having intense signals, such as the subcutaneous lipid in the head, effective reduction of truncation artifacts can be achieved by obtaining an extended k-space coverage for these regions. In this paper, a hybrid technique which employs phase-encoded spectroscopic imaging (SI) to cover the central portion of the k-space and echo-planar spectroscopic imaging (EPSI) to measure the peripheral portion of the k-space is developed. EPSI, despite its inherently low SNR characteristics, provides a sufficient SNR for outer high-spatial frequency components of the aforementioned high signal regions and supplies an extended k-space coverage of these regions for the reduction of truncation artifacts. The data processing includes steps designed to remove inconsistency between the two types of data and a previously described technique for selectively retaining only outer k-space information for the high signal regions during the reconstruction. Experimental studies, in both phantoms and normal volunteers, demonstrate that the hybrid technique provides significant reduction in truncation artifacts.

Modulation of nonprotein sulphydryl compounds rhythm with buthionine sulphoximine: relationship with oxaliplatin toxicity in mice

The relationship between the rhythm in tissue nonprotein sulphydryl groups (NPSH) and that in 1,2-diamine (trans-I)-cyclohexane oxalatoplatinum (1-OHP) toxicity was investigated in a total of 266 male B6D2F1 mice, using buthionine sulphoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase. Mice were synchronized with an alternation of 12 h light (L) and 12 h darkness (D; LD 12:12), and circadian time was expressed in hours after light onset (HALO). NPSH was measured in liver, jejunum and bone marrow at 0, 8 and 16 HALO. Dosing 1-OHP at these times achieved intermediate. high or low toxicity respectively. The physiological circadian rhythm in NPSH content was statistically significant in all tissues studied, with a maximum at the transition from D to L (0 HALO). BSO administration (450 mg/kg i.p., 4 h before sampling) induced a large depletion in liver and jejunum NPSH at their physiological peak (0 HALO), but exerted no significant effect at their trough (8 HALO). As a result, 24 h rhythm was suppressed in liver and jejunum, but remained similar to the physiological one in bone marrow. BSO enhanced 1-OHP-induced mortality and jejunal toxicity, but exerted no significant effect upon bone marrow toxicity. Despite these differences, 1-OHP remained least toxic at 16 HALO, near the middle of the dark span, which corresponds to maximum activity in the circadian rest/activity cycle. Our results show that mean NPSH levels in liver seem to account for the mean level of 1-OHP toxicity, while jejunal NPSH rhythm plays an important role in the intestinal toxicity rhythm of this drug.

Effects of boswellic acids extracted from a herbal medicine on the biosynthesis of leukotrienes and the course of experimental autoimmune encephalomyelitis

Mixed acetylboswellic acids, pentacyclic triterpenes extracted from the gum resin of Boswellia serrata Roxb., significantly inhibited the ionophore-stimulated release of the leukotrienes (LT) B4 and C4 from intact human polymorphonuclear neutrophil leukocytes (PMNLs), with IC50 values of 8.48 micrograms/ml and 8.43 micrograms/ml, respectively. Purified acetyl-11-keto-beta-boswellic acid was about three times more potent as inhibitor of the formation of both LTB4 (IC50 = 2.53 micrograms/ml) and LTC4 (IC50 = 2.26 micrograms/ml) from human PMNLs in the same assay. The comparative agent MK 886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]- 2,2-dimethylpropanoic acid, L-663,536, CAS 118, 414-82-7) was about 10 to 100-fold more active than the boswellic acids in inhibiting the formation of 5-lipoxygenase products in human PMNLs, with IC50 values of 0.0068 microgram/ml (LTB4) and 0.49 microgram/ml (LTC4). After daily intraperitoneal dosage the extract of mixed acetylboswellic acids (20 mg/kg) significantly reduced the clinical symptoms in guinea pigs with experimental autoimmune encephalomyelitis (EAE) between days 11 and 21. However, the inflammatory infiltrates in the brain and the spinal cord were not significantly less extensive in the treated animals than in the respective control group. The multiple intraperitoneal application of boswellic acids did not inhibit the ionophore-challenged ex vivo release of leukotrienes B4 and C4 from PMNLs separated from the blood of guinea pigs with EAE. The boswellic acids have thus been characterized as selective, non-redox and potent inhibitors of the biosynthesis of leukotrienes in vitro.

Pharmacologic restoration of suppressed temperature rhythms in rats by melatonin, melatonin receptor agonist, S20242, or 8-OH-DPAT

Endogenous circadian rhythms in body temperature and locomotor activity rhythms are suppressed in Sprague-Dawley rats exposed to prolonged continuous light, possibly as a result of a profound alteration of the melatonin secretion rhythm. The ability to restore circadian system function with either exogenous melatonin, or melatonin receptor agonist S20242 (N-[2-(7-methoxy napth-1-yl)ethyl] propionamide), or 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), was investigated under these conditions. Seven rats received a daily 6-h intravenous infusion of melatonin (0.01 mg kg(-1)) for 10 days, which generates a nearly physiological circadian rhythm of urinary 6-sulfatoxy-melatonin, the main urinary metabolite of melatonin. Nevertheless, there was no effect on body temperature or locomotor activity rhythms. Then, 49 rats received daily subcutaneous melatonin (0.01, 1 or 5 mg kg(-1) day(-1)), S20242 (1 or 5 mg kg(-1) day(-1)) or 8-OH-DPAT (5 mg kg(-1) day(-1)) for 30 days. The circadian rhythm in body temperature was restored by subcutaneous melatonin or by S20242 as a function of the dose or by 8-OH-DPAT. The effect started within the first 10 days of treatment and persisted for I to 3 weeks following the end of treatment in 8 of 10 rats receiving melatonin, in 9 of 11 rats treated with S20242 and in 1 of 4 rats treated with 8-OH-DPAT. Activity was less susceptible to entrainment than temperature with these drugs, since circadian rhythmicity was restored in only 2 of 6 rats treated with melatonin and in 1 of 4 rats treated with 8-OH-DPAT. These data demonstrate a specific action of subcutaneous melatonin, S20242 or 8-OH-DPAT on temperature rather than on activity rhythms. This differential effect on two major outputs of the suprachiasmatic nucleus further supports the existence of two independent oscillators in this hypothalamic circadian clock, which may be considered as separate pharmacological targets in the circadian system.

Persistent T lymphocyte rhythms despite suppressed circadian clock outputs in rats

Circadian rhythms in circulating leukocyte and lymphocyte counts persisted with halved amplitudes in constant light (LL) of 300 lx intensity for 8 wk, whereas circadian rhythms in body temperature, locomotor activity, and plasma catecholamines were completely suppressed. Subsequent exposure to constant darkness (DD) normalized all circadian rhythms within 2 wk. Rhythms in circulating T lymphocyte subsets were studied in LL or DD using double labeling with monoclonal antibodies and flow cytometry. Circadian rhythms were suppressed for leukocytes and lymphocytes but were maintained for both T helper cells (Th) and T cytotoxic cells (Ts) lymphocytes after 11 wk in LL. A group 24-h rhythm was only validated for total lymphocytes after 16 wk in LL. However, individual total, Th, and Ts lymphocytes maintained their usual respective phase relationships in each rat. The alteration of immune cell circulatory rhythms likely stemmed from a progressive loss of circadian synchronization among rats kept in LL. Conversely, after 11 or 16 wk in DD, leukocytes and lymphocyte subsets circadian rhythms were maintained. Thus catecholamines do not drive circulatory T cell rhythms. The loss of coupling between T lymphocyte rhythms and three major outputs of the circadian system further supports the hypothesis of an independent immunologic oscillator.

Pharmacologic modulation of reduced glutathione circadian rhythms with buthionine sulfoximine: relationship with cisplatin toxicity in mice

The relationship between the rhythm in reduced glutathione (GSH) and that in cisplatin (CDDP) toxicity was investigated in a total of 560 male B6D2F1 mice, using buthionine sulfoximine (BSO). GSH was measured by high-performance liquid chromatography (HPLC) in four tissues, at each of six sampling times, 4 hr apart. A significant 24-hr rhythm was statistically validated in liver, jejunum, and colon, but not in bone marrow. Relative to liver, glutathione content was 56% in colon, 38% in bone marrow, 25% in jejunum, and negligible in kidney, where cysteine, a final product of GSH catabolism, displayed a 12-hr rhythmic variation. This rhythm may reflect that in the activity of GSH-degrading enzymes. BSO (450 mg/kg ip, 4 hr before sampling) reduced liver GSH threefold and kidney cysteine content was halved, but this pretreatment had no significant effect upon GSH content in the other organs. Furthermore, the period of the physiologic liver GSH rhythm changed from 24 hr to a composite (24 + 12 hr) period. This change in the period may result from an unmasking of the 12-hr rhythm in GSH-degrading enzyme activity by GSH synthesis blockade. Maximal values occurred in the mid-rest span and in the mid-active span after BSO administration. In the other tissues, the 24-hr period remained unchanged. BSO injection largely enhanced CDDP toxicity (as assessed by survival, leukopenia, and histologic lesions in kidney and bone marrow) and kidney mean platinum concentration. Furthermore, BSO pretreatment modified the period of CDDP toxicity rhythm: survival followed a significant 12-hr-rhythm, instead of a 24-hr rhythm. The cycling of GSH concentration results from a balance between synthesis and catabolism and likely constitutes one of the main components of the circadian rhythm in CDDP toxicity in mice.

Pharmacokinetically guided melatonin scheduling in rats with circadian system suppression

To obtain a pharmacologic effect of melatonin in rats kept under prolonged continuous light exposure, conditions known to produce functional suppression of the circadian system, mimicking of the physiologic 24-h pattern of melatonin secretion, a hormonal signal of darkness exposure may be needed. The delivery scheme for melatonin was established in rats in the present studies. First, the plasma pharmacokinetics of [3H]melatonin were determined in rats kept under continuous light and in rats synchronized by exposure to alternating 12 h light and 12 h darkness (LD 12:12) in the early light span. The pharmacokinetics of total radioactivity were similar in both groups. Further quantitation of melatonin by thin-layer chromatography revealed differences dependent on light conditions. The mean plasma clearance and steady-state distribution volume were approximately twice as low with continuous light as with LD 12:12. Plasma protein binding of melatonin was approximately 33%, irrespective of group or sampling time. These pharmacokinetic parameters were used to devise a 24-h periodic delivery schedule consisting of a 6-h constant infusion of exogenous melatonin, followed by an 18-h melatonin-free interval. In a second study, the melatonin 24-h pattern was estimated from the measurement of 2-h fractions of urinary 6-sulfatoxymelatonin excretion for 4 days. 6 unrestrained rats kept under continuous light received melatonin for 2 days from 22:00 to 04:00 h through an indwelling jugular catheter, connected to a reservoir from a programmable pump. Only the administration of low doses (0.01 mg/kg/day) resulted in both a circadian pattern for 6-sulfatoxymelatonin excretion and normal physiological values during the infusion-free intervals. The resynchronizing efficacy of this schedule should be tested in rats with functional suppression of the circadian system.

[Rhythmic component of twelve hours]

From observations made on the rhythms in different systems: changes in plasmatic concentrations of 5-fluorouracil administered at a constant rate, proliferative activity of human tissues (bone marrow and oral mucosa), actometry, variations of glutathione levels in the liver and kidney from ice, we show the existence of a 12 hours rhythmic component and we discuss the putative importance of this component.

[Analyses of rhythms of the body temperature in free running in rats]

We have previously observed a light-induced suppression of circadian rhythms of body temperature and locomotor activity in 50/55 male Sprague Dawley rats (Am. J. Physiol., 1995). This study presents a description of 4 records of body temperature obtained by telemetry and compares three methods of period analysis (Fourier analysis, autocorrelation and cosinor). In case of persistant circadian rhythms, Fourier analysis and cosinor method agree and allow description of rhythm parameters. However, in case of an alteration of the circadian system in continuous light, these 2 methods can disagree on the dominant period. Autocorrelation analysis permits to conclude on the absence of circadian and ultradian rhythmicity. These results demonstrate the necessity to associate several methods for period analysis and plaids for the development of a strategy for data processing of longitudinal time series.

Two consecutive phase II studies of oxaliplatin (L-OHP) for treatment of patients with advanced colorectal carcinoma who were resistant to previous treatment with fluoropyrimidines

BACKGROUND

Oxaliplatin (L-OHP) is a platinum complex that possesses activity against human and murine cells in vitro and in vivo, including colorectal carcinoma-derived cell lines, and cells that have been selected for resistance to cisplatin. We report two consecutive phase II trials of L-OHP for treatment of patients with advanced colorectal carcinoma.

PATIENTS AND METHODS

Fifty-eight patients were entered in study I, and 51 patients in study II. All of the patients had tumor progression when they were treated, prior to their enrollment, with a fluoropyrimidine-containing regimen. In both trials treatment consisted of L-OHP, 130 mg/m2, by i.v. infusion for two hours; the treatment was repeated every 21 days.

RESULTS

Response to therapy: Study I: Fifty-five patients were assessed for response. The response rate was 11% (95% CI, 0.03-0.19). Study II: All 51 patients were assessed for response. The response rate was 10% (95% CI, 0.017-0.18). The overall response rate for the 106 evaluated patients was 10% (95% CI, 0.046-0.16). Times to disease progression in responders were 4, 4, 4.5+, 5, 5, 6, 6, 6, 6+, 9, and 13 months. The dose-limiting toxic effect was sensory peripheral neuropathy. The incidence of severe peripheral neuropathy grades was: Study I: grade 3, 23% of patients, and grade 4, 8% of patients. Severe neuropathy had a favorable course in all of the patients who had long-term neurologic follow-up. Diarrhea and myeloid impairment were minor.

CONCLUSION

L-OHP produced modest, but definite antitumor activity in patients with advanced colorectal carcinoma who were previously resistant to chemotherapy including fluoropyrimidines. Toxicity is within acceptable limits of tolerance at the dose and schedule of oxaliplatin used in this trial.

Chronomodulation of chemotherapy against metastatic colorectal cancer. International Organization for Cancer Chronotherapy

Toxic effects of 5-fluorouracil (5-FU) and oxaliplatin (L-OHP), two active drugs against metastatic colorectal cancer, varied by 50% or more according to circadian dosing time in mice or rats. Adaptation of chemotherapy delivery to circadian rhythms (chronotherapy) was assessed in fully ambulatory outpatients, using multichannel programmable pumps. These devices allowed us to reliably test the clinical relevance of such a chronotherapy principle. First, single agent 5-day chronomodulated schedules were devised and assessed in Phase I and II trials with 5-fluorouracil (5-FU, peak delivery at 4:00 h) or oxaliplatin (L-OHP, peak at 16:00 h). Both schedules were then combined, folinic acid (FA) being added, synchronous with 5-FU infusion. This three-drug chronomodulated regimen (chrono-FFL) produced a 58% response rate (95% C.I.: 48-68%) in 93 patients with metastatic colorectal cancer, 46 of whom had previously received chemotherapy. In the first European randomised trial in 92 previously untreated patients, chronomodulated three-drug delivery achieved 53% response, as compared to 32% in those patients receiving flat infusion (P = 0.038). These respective figures were confirmed in a subsequent multicentre randomised trial involving 186 additional patients. Since the most active schedule was also the least toxic one by 2- to 10-fold, chrono-FFL was further intensified in three consecutive Phase II trials involving a total of 200 additional patients. Results suggest that both response rate and quality were further improved with such treatment intensification. Thus, chrono-FFL more than doubled the activity of chemotherapy against metastatic colorectal cancer in a multicentre European setting.(ABSTRACT TRUNCATED AT 250 WORDS)

Light-induced suppression of the rat circadian system

In a constant environment, circadian rhythms persist with slightly altered period lengths. Results of studies with continuous light exposure are less clear, because of short exposure durations and single-variable monitoring. This study sought to characterize properties of the oscillator(s) controlling the rat's circadian system by monitoring both body temperature and locomotor activity. We observed that prolonged exposure of male Sprague-Dawley rats to continuous light (LL) systematically induced complete suppression of body temperature and locomotor activity circadian rhythms and their replacement by ultradian rhythms. This was preceded by a transient loss of coupling between both functions. Continuous darkness (DD) restored circadian synchronization of temperature and activity circadian rhythms within 1 wk. The absence of circadian rhythms in LL coincided with a mean sixfold decrease in plasma melatonin and a marked dampening but no abolition of its circadian rhythmicity. Restoration of temperature and activity circadian rhythms in DD was associated with normalization of melatonin rhythm. These results demonstrated a transient internal desynchronization of two simultaneously monitored functions in the rat and suggested the existence of two or more circadian oscillators. Such a hypothesis was further strengthened by the observation of a circadian rhythm in melatonin, despite complete suppression of body temperature and locomotor activity rhythms. This rat model should be useful for investigating the physiology of the circadian timing system as well as to identify agents and schedules having specific pharmacological actions on this system.

A phase I-II trial of five-day continuous intravenous infusion of 5-fluorouracil delivered at circadian rhythm modulated rate in patients with metastatic colorectal cancer

The toxicity of 5-fluorouracil (5-FU) was decreased by two to eight-fold if this drug was injected in mice near the middle of the day (rest span) rather than in the middle of the night (activity span). If the rhythm in 5-FU toxicity is linked to the sleep-wakefulness endogenous circadian cycle across species, the least toxic time in man would correspond to 4.00 hours at night. The availability of a single-reservoir programmable-in-time external ambulatory pump (Chronopump, Autosyringe, Hooksett, USA) allowed us to perform a first test of this hypothesis. Five-FU was infused for 5 consecutive days, via an implanted venous access port, with peak drug delivery at 4.00 hours and no infusion from 18.00 to 22.00 hours. Each course was repeated after a free interval of 16 days. Intrapatient dose escalation was planned from 4 to 9 g/m2/course (800 to 1800 mg/m2/day x 5 days) if toxicity was less than grade 2 according to the World Health Organization (W.H.O.). Thirty-five patients with metastatic colorectal cancer were treated; 15 (41%) had received previous therapy, 22 (63%) had W.H.O. performance status of 2 or greater, and 19 (54%) had two or more sites involved. Grade 2 or greater toxicity was encountered in less than 5% of the courses, indicating an adequate control of toxicity via dose adjustment. Oral mucositis, diarrhea, and/or hand-foot syndrome limited dose escalation, and their incidence was dose dependent. Median maximal tolerated dose was 7.5 mg/m2/course in 30 patients assessed for this endpoint.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian changes in mitoxantrone toxicity in mice: relationship with plasma pharmacokinetics

Circadian time-dependent differences in clinical toxicity of several anti-cancer agents were predicted from murine studies. Mitoxantrone is an anthracenedion (an anthracycline-related class of compounds) of increased clinical use, which may benefit from selective circadian timing. In 3 consecutive studies, a total of 428 male B6D2F1 mice aged from 8 to 10 weeks were synchronized by an alternation of 12 hr of light and 12 hr of darkness (LD 12:12). They received a single i.v. injection of mitoxantrone at one of 6 or 4 circadian stages differing by 4 or 6 hr. A dose-response relationship characterized body-weight loss and survival rate. Dose-toxicity relationship further closely depended upon circadian dosing time. Thus, a dose of 16 mg/kg killed 100% of the mice injected at 3 hr after light onset (HALO), and none of them at 11 or at 15 HALO (p from chi 2 < 0.001). Body-weight loss varied from 41% at 3 HALO to 32% at 15 HALO (p from ANOVA < 0.0001). Least hematologic toxicity and fastest recovery of a normal circulating leukocyte count corresponded to mitoxantrone injection near the middle of the dark-activity span, at 16 HALO. Similar findings characterized colonic and splenic lesions. Moreover, mitoxantrone was both distributed and eliminated faster after injection at 16 HALO. If such data apply to cancer patients, as was the case for other drugs investigated with this methodology, an afternoon infusion should enable high-dose mitoxantrone to be well tolerated.

Spontaneous or imposed circadian changes in plasma concentrations of 5-fluorouracil coadministered with folinic acid and oxaliplatin: relationship with mucosal toxicity in patients with cancer

Pharmacokinetics of total platinum, 5-fluorouracil, l-folinic and d-folinic acid, and 5-methyltetrahydrofolate were studied in plasma from nine patients with advanced colorectal cancer treated with oxaliplatin (20 mg/m2/day), 5-fluorouracil (600 mg/m2/day), and folinic acid (300 mg/m2/day). Drugs were administered with a programmable-in-time pump by continuous infusion for 5 days. We compared two drug delivery schedules: constant rate versus chronomodulated rate with peak of oxaliplatin at 4 pm and peak of 5-fluorouracil and folinic acid at 4 am. In the chronomodulated schedule, plasma concentrations of the drugs paralleled the pump functioning: maximum platinum concentration near 4 pm, and maximum 5-fluorouracil and folate concentrations near 4 am. When drugs were administered at a constant rate, mean plasma concentration of 5-fluorouracil varied in a circadian manner each treatment day, that is, a peak at 4 am (approximately 800 ng/ml) and a trough at 1 pm (approximately 100 ng/ml). Mean plasma levels of total platinum and folate compounds increased over the first 24 hours. Total platinum mean level and that of the inactive d-folinic acid isomer reached a constant plasma concentration, whereas biologically active folates exhibited circadian variation in their plasma concentrations (peak around 7 am, trough near 6 pm, and amplitude approximately 10%). Severe mucositis was exhibited by all four patients on the flat schedule, but only by one on the chronomodulated schedule (p < 0.008). Individual pharmacokinetic and toxicity data showed that patients with circadian rhythms in 5-fluorouracil concentrations were least sensitive to 5-fluorouracil-related toxicity. Thus amplification or induction of such rhythm in 5-fluorouracil exposure may permit dose escalation.

5-Fluorouracil combined with the [6S]-stereoisomer of folinic acid in high doses for treatment of patients with advanced colorectal carcinoma. A phase I-II study of two consecutive regimens

BACKGROUND

Potentiation of the antitumor activity of 5-fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase (TS), fluorodeoxyuridylate (FdUMP), and methylene tetrahydrofolate (5,10-CH2-FH4), which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C6 carbon of the pteridine ring. Only the levorotatory [6S]-folinic acid is transformed into active folate cofactors. However, the [6R]-stereoisomer is not inert; it was shown to interfere with the [6S] form at the cellular level. The possibility of a deleterious effect of the unnatural stereoisomer on the modulation of 5-FU led us to carry out 2 consecutive phase I-II studies of 5-FU combined with the [6S]-stereoisomer of folinic acid given in high doses for treatment of patients with advanced colorectal carcinoma.

PATIENTS AND METHODS

Treatment comprised 5-FU by i.v. infusion for 2 hours (the initial dose was 350 mg/m2/d; it was incremented by 25 mg/m2/d until a maximal dose of 550 mg/m2/d) and [6S]-folinic acid (100 mg/m2/d by rapid i.v. injection in Regimen 1, and 100 mg/m2 by rapid i.v. injection followed by a 2-hour infusion of 250 mg/m2 in Regimen 2) for 5 days, every 21 days. Twenty-five pts and 27 pts were assessed in Regimen 1 and in Regimen 2, respectively. They had had no prior chemotherapy. The median follow-up time was 9 months and 15.5 months for patients treated with Regimen 1 and Regimen 2, respectively. For pts treated with Regimen 1, the response rate was 52% (CR, 12%; PR, 40%). The median time to disease progression was 9.2 months. The probability of survival at 12 months was 73%. For pts treated with Regimen 2, the response rate was 37% (CR, 7%; PR, 30%). The median time to disease progression was 8.9 months. The probability of survival at 12 months was 67%. Improvement in quality of life was achieved in most patients who had symptoms due to the tumor before the start of treatment. The dose-limiting toxic effects (WHO grades > or = 3) were diarrhea, dermatitis, and mucositis. One single episode of grade 4 diarrhea occurred. After injection according to the schema in Regimen 1, [6S]-folinic acid was rapidly cleared from plasma (mean t 1/2 alpha and t 1/2 beta of 7.2 and 126 minutes, respectively). The mean concentration of the [6S]-stereoisomer two hours after injection was 5.8 mmol/L. After a rapid i.v. injection of 100 mg/m2 followed by a 2-hour infusion of 250 mg/m2, the mean concentration of [6S]-folinic acid two hours after the injection was 57.5 mmol/L. Pharmacokinetic data suggests saturation of the metabolic conversion of [6S]-folinic acid when large doses are administered.

CONCLUSION

The [6S]-form of folinic acid potentiates the antitumor effect of 5-FU given concomitantly. However, increase of the daily dose of the folate did not result in a therapeutic improvement. The present results justify a more complete exploration of the pure active stereoisomer as a modulator of the fluoropyrimidines.

Fluorouracil combined with the pure (6S)-stereoisomer of folinic acid in high doses for treatment of patients with advanced colorectal carcinoma: a phase I-II study

BACKGROUND

Potentiation of the antitumor activity of fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase, fluorodeoxyuridine monophosphate, and methylene tetrahydrofolate, which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C-6 carbon of the pteridine ring. Only the levorotatory (6S)-stereoisomer of folinic acid is transformed into active folate cofactors. However, the (6R)-stereoisomer of folinic acid is not inert; it was shown to interfere with the (6S) form at the cellular level.

PURPOSE

The possibility of a deleterious effect of the unnatural stereoisomer on the modulation of 5-FU led us to carry out a phase I-II study of 5-FU combined with the (6S)-stereoisomer of folinic acid given in high doses for treatment of patients with advanced colorectal carcinoma. We also determined the plasma pharmacokinetics of folates after intravenous (IV) injection of (6S)-folinic acid at the dose used in this study.

METHODS

Treatment consisted of 5-FU (350-550 mg/m2 per day by IV infusion for 2 hours) and (6S)-folinic acid (100 mg/m2 per day by IV bolus injection) given for 5 consecutive days; the treatment was repeated every 21 days. Twenty-five patients with advanced colorectal carcinoma, who had had no prior chemotherapy, were evaluated for antitumor activity. The quantity of folates in plasma was measured using a microbiological assay.

RESULTS

The median follow-up time was 9 months (range, 3.5-15.2 months). The response rate was 52% (complete response, 12%; partial response, 40%). The median time to disease progression for responding patients was 9.2 months (range, 5.9-15+ months). The estimated probability of survival at 12 months was 73%. Palliative improvement in quality of life was achieved in most patients who had symptoms due to the tumor before the start of treatment. The dose-limiting toxic effects were grade 3 diarrhea, dermatitis, and oral mucositis. Grade 4 toxicity did not occur. Myeloid toxicity was minor. After IV injection, (6S)-folinic acid was rapidly cleared from plasma (mean half-lives: alpha = 7.2 minutes and beta = 126 minutes). The mean concentration of the unchanged compound 2 hours after injection was 5.8 mumol/L.

CONCLUSION

The (6S)-form of folinic acid potentiates the antitumor effect of 5-FU given concomitantly.

IMPLICATION

Our results justify a more complete exploration of the pure active stereoisomer as a modulator of the fluoropyrimidines.

A chronopharmacologic phase II clinical trial with 5-fluorouracil, folinic acid, and oxaliplatin using an ambulatory multichannel programmable pump. High antitumor effectiveness against metastatic colorectal cancer

A significant increase in the dose intensity of chemotherapy with fluoropyrimidines and platinum complexes has resulted from selective circadian timing and/or circadian modulation of the infusion rate. The relevance of such chronopharmacologic strategy for improving the outcome of metastatic colorectal cancer was evaluated in an extended Phase II clinical trial involving 93 patients. Of these, 49% previously had received chemotherapy and/or radiation therapy. The drugs 5-fluorouracil (5-FU, 700 mg/m2/d) and folinic acid (FA, 300 mg/m2/d) combined with oxaliplatin (l-OHP, a nonnephrotoxic platinum complex, 25 mg/m2/d) were infused continuously for 5 days every 3 weeks. In a pilot randomized study, the infusion of all three drugs at a constant rate resulted in World Health Organization (WHO) Grade 3 or 4 toxicity in all four patients compared with no such toxicity in four patients if the infusion rate was modulated according to circadian rhythms. In this Phase II trial, drug delivery was modulated sinusoidally over the 24-hour day with peak flow rates at 4 AM for 5-FU and FA and at 4 PM for l-OHP, using an ambulatory programmable-in-time pump. All patients and 784 of 839 courses (93%) were evaluable for toxicity. Dose-limiting toxicities (WHO Grade 2 to 4) included diarrhea (19% of courses) and vomiting (35% of courses). In addition, WHO Grade 2 to 4 hematologic or mucosal toxicity, respectively, occurred in 2.5% and 7% of courses. Two toxic deaths were encountered. Peripheral sensory neuropathy led to discontinuation of l-OHP in 14 patients after 7 to 12 courses; it completely disappeared within 3 months. Fifty-four of the 93 patients had an objective response (58%; 95% confidence limits, 48% to 68%), irrespective of previous treatment or prior documented progression while receiving standard chemotherapy with 5-FU and FA or continuous 5-FU. Complete responses (CR) were seen in 6 patients (4 of which were proved histologically) and, after surgery, in 12 additional patients (overall CR rate, 18 of 93 [19%]; 95% confidence limits, 11% to 27%). Median progression-free survival (PFS) and overall survival were, respectively, 10 and 15 months, irrespective of prior therapy. Both PFS and survival were significantly longer in patients with a good performance status (PS, 0 or 1, by WHO criteria; respectively, 12 and 21 months) than in patients with poor PS (respectively, 8 and 10 months; P less than 0.01, by log-rank test). This chronopharmacologic protocol may have circumvented, to some extent, both the natural and acquired resistance of colorectal cancer to chemotherapy.

Spinal epidural hematoma following epidural anesthesia versus spontaneous spinal subdural hematoma. Two case reports

Two cases of lumbar hemorrhage with subsequent persistent neurologic sequelae are presented and their possible causes are discussed in the context of a literature review: one patient with spontaneous spinal subdural hematoma with no trauma or lumbar puncture and one with spinal epidural hematoma associated with preceding epidural catheterization for postoperative pain relief. The subdural hematoma was associated with a thrombocytopenia of about 90,000/microliters due to intraoperative blood loss. This might have been contributory to the formation or expansion of the hematoma, but it is not convincing since a platelet count of this amount should not lead to spontaneous bleeding. Both patients received low-dose heparin, but since coagulation tests were normal, prolonged bleeding does not appear to be a likely cause, although it cannot be excluded. In conclusion, the reasons for both hematoma remain unclear. With regard to the epidural hematoma and low-dose heparinization, the possible coincidence of spontaneous lumbar hematoma and lumbar regional block should be taken into consideration.

Urapidil-induced increase of the intracranial pressure in head-trauma patients

This report deals with two patients suffering from a closed head injury who demonstrated a rise of intracranial pressure (ICP) after bolus injections of urapidil to control arterial hypertension. The rapid fall of the arterial pressure was accompanied by an increase of ICP that amounted to approximately 50% to 100% of the initial values (and thereby reaching ICP values between 32.5 and 40 mmHg); cerebral perfusion pressure decreased to less than 50 mmHg, and nearly reached control values at 15 min after administration of urapidil. The mechanism for this ICP rise is unknown and remains speculative. So far, no other clinical or experimental data are known to us reporting a urapidil induced increase of ICP in head trauma patients.

[A paradoxical air embolism in a closed foramen ovale]

This case report deals with a patient who was being operated on for a tumor of the colon and who died from a paradoxical venous air embolism. Accompanying massive blood loss impedes differentiation of hemodynamic disturbances either due to venous air embolism or to hemorrhage, respectively. Air was aspirated from the radial artery catheter that was used for blood-pressure monitoring and for taking blood samples for laboratory analysis. At autopsy, no probe-patent foramen ovale could be demonstrated. The mechanism of air passing from the venous to the systemic circulation in our patient remains speculative; however, mechanical cardiopulmonary reanimation itself with its underlying thoracic pump mechanism has to be considered as contributing to the transport of air from the venous to the arterial side of the circulation.

Tricyclic antidepressant-specific Fab fragments alter the distribution and elimination of desipramine in the rabbit: a model for overdose treatment

The effects of tricyclic antidepressant (TCA)-specific Fab fragments (Fab) on total and free desipramine (DMI) levels in serum and urine of DMI-treated rabbits were studied to determine the feasibility of using these Fab for antidotal treatment of TCA overdoses in humans. Serial samples of blood and urine were collected from two 3 kg rabbits after arterial injection of 2 mg 3H-DMI and, about 1.5 hr later, after injection of approximately 1 g Fab (prepared from sheep total IgG). Protein-free filtrates of serum and urine samples were obtained by ultrafiltration; concentrations of apparent total and apparent free DMI (apparent DMI, aDMI = DMI + metabolites) were calculated based on the radioactivity in the sample and ultrafiltrate, respectively. Treatment with Fab induced significant changes in the absolute and relative concentrations of free and total aDMI in both serum and urine. Changes in the serum included increases in the total and free aDMI levels. Changes in the urine included the appearances of a protein-bound aDMI fraction and Fab, and an increase in the percent of unmetabolized DMI. These results demonstrate that TCA-specific Fab influence the distribution and elimination of desipramine in DMI-treated rabbits and suggest that further studies on the use of TCA-specific Fab for antidotal treatment of TCA overdose are warranted.

Enhanced activity of mouse peritoneal cells after aclacinomycin administration

We have investigated the activation of mouse peritoneal macrophages by injection of aclacinomycin (ACM). Macrophages from ACM-treated mice have an increased phagocytic activity as measured by Candida ingestion. The microbicidal activity indirectly evaluated by chemiluminescence and superoxide determination in response to stimulation with zymosan and 4 beta-phorbol-12-myristate-13 alpha-acetate is also greater in the cells from treated mice. Direct measurement of the cytostatic function, and of in vitro and in vivo cytotoxicity shows comparable significant increases against L1210 or P815 target cells. The enhanced antitumoral activity could not be attributed to the residual presence of ACM in the peritoneal cells since no drug was detected by high-performance liquid chromatography and since their freeze-thaw lysates incubated with P815 cells did not modify the growth of tumor cells as measured by [3H]-thymidine incorporation. We also checked that the presence of ACM did not influence the intensity of the chemiluminescence. In all tests performed, only i.p. ACM administration could stimulate the peritoneal cells. Since the doses of ACM inducing an increase in macrophage activity are effective on the survival of tumor-bearing mice, the participation of this mechanism in tumor control might be suggested.