Micro-mechanical fracture dynamics and damage modelling in brittle materials.

This study explores the interplay between wave propagation and damage in brittle materials. The damage models, based on micro-mechanical fracture dynamics, capture any possible unstable growth of micro-cracks, introducing a macroscopic loss of stability. After stating the non-dimensional mathematical problem describing the wave propagation with damage, we introduce a non-dimensional number, called the microscopic evolution index, which links the micro and macro scales and discriminates the microscopic scale behaviour. For large values of microscopic evolution index, corresponding to a microscopic quasi-static process coupled with a macroscopic dynamic one, the macroscopic dynamic system could lose its hyperbolicity or become very stiff and generate shock waves. A semi-analytical solution to the one-dimensional wave propagation problem with damage, which could be very useful in the accuracy evaluation of the numerical schemes, was constructed. Concerning the asymptotic behaviour of the dynamic exact solution on the microscopic evolution index (or on the strain rate), an important strain rate sensitivity was found: the pulse loses its amplitude for decreasing strain rate and, starting with a critical value, the micro-scale model is rate independent. A possible regularization technique to smooth the shock waves at low and moderate strain rates is discussed. Finally, some numerical results analyse the role played by the the friction on the micro-cracks in the damage modelling of blast wave propagation. This article is part of the theme issue 'Fracture dynamics of solid materials: from particles to the globe'.

Continuous flow aerobic granular sludge reactor for dairy wastewater treatment.

The focus of this study was to assess the treatment performance and granule progression over time within a continuous flow reactor. A continuous flow airlift reactor was seeded with aerobic granules from a laboratory scale sequencing batch reactor (SBR) and fed with dairy wastewater. Stereomicroscopic investigations showed that the granules maintained their integrity during the experimental period. Laser diffraction investigation showed proof of new granules formation with 100-500 µm diameter after only 2 weeks of operation. The treatment performances were satisfactory and more or less similar to the ones obtained from the SBR. Thus, removal efficiencies of 81-93% and 85-94% were observed for chemical oxygen demand and biological oxygen demand, respectively. The N-NH(+)(4) was nitrified with removal efficiencies of 83-99% while the nitrate produced was simultaneously denitrified - highest nitrate concentration determined in the effluent was 4.2 mg/L. The removal efficiency of total nitrogen was between 52 and 80% depending on influent nitrogen load (39.3-76.2 mg/L). Phosphate removal efficiencies ranged between 65 and above 99% depending on the influent phosphate concentration, which varied between 11.2 and 28.3 mg/L.

Incidence and risk factors of EBV reactivation after unrelated cord blood transplantation: a Eurocord and Société Française de Greffe de Moelle-Therapie Cellulaire collaborative study.

EBV viremia and post-transplantation lymphoproliferative disorders (PTLDs) have been associated with high mortality rates after allogeneic hematopoietic SCT (allo-HSCT). Few retrospective studies, without EBV load monitoring postulated that umbilical cord blood transplantation (UCBT) might be associated with high incidence of EBV events. We retrospectively studied 175 UCBT recipients for whom RQ-PCR was used to monitor EBV blood load at least once a week during the first 3 months after UCBT. Median age was 23 years, 74% had leukemia. Conditioning was myeloablative in 54% and reduced intensity conditioning (RIC) was used in 46%. A total of 24 patients presented an EBV reactivation. For 15 patients, the reactivation occurred during the first 100 days (cumulative incidence: 8%) and included 4 EBV-PTLD. Rituximab as preemptive treatment was used in 12 of these 15 patients. In univariate analysis, the increased risk of early EBV reactivation was associated with RIC in combination with antithymocyte globulin (P=0.03) and previous history of auto-HSCT (P=0.01). Multivariate analysis did not find any independent risk factor. EBV reactivation as time-dependent covariate was not statistically associated with survival. Therefore, EBV events were not major complications after UCBT when EBV load is weekly monitored and preemptive treatment started.

Unrelated cord blood transplantation in adults with myelodysplasia or secondary acute myeloblastic leukemia: a survey on behalf of Eurocord and CLWP of EBMT.

The aim of our study was to evaluate, through the Eurocord and European Group for Blood and Marrow Transplantation (EBMT) registries, outcomes and risk factors for outcomes in adult patients who underwent single or double unrelated cord blood transplantation (UCBT) for myelodysplastic syndrome (MDS) or secondary acute myeloblastic leukemia (sAML). A total of 180 adults with MDS (n=39) or sAML (n=69) were analyzed. Risk factors for outcomes were analyzed using the Fine and Gray method and the Cox model. Median age was 43 (18-72) years. In all, 77 patients (71%) received a single UCBT. Myeloablative conditioning regimen (MAC) was given to 57 (53%) patients. Median numbers of nucleated and CD34(+) cells at freezing were 3.6 × 10(7) and 1.1 × 10(5) kg. At 60 days, cumulative incidence of neutrophil recovery was 78±4% and was independently associated with the number of CD34(+) cells per kg (>1.1 × 10(5); P=0.005) and advanced disease status (blasts <5% at time of UCBT, P=0.016). A 2-year non-relapse mortality (NRM) was significantly higher after MAC (62 vs 34%; P=0.009). A 2-year disease-free-survival (DFS) and overall survival (OS) were 30 and 34%, respectively. In multivariate analysis, patients with high-risk disease (blasts >5% and International Prognostic scoring system (IPSS) intermediate-2 or high in MDS) had significant poorer DFS (hazard ratio (HR): 1.76; P=0.047). In spite of high NRM, these data indicate that UCBT is an acceptable alternative option to treat adults with high-risk MDS or sAML, without a suitable human leukocyte antigen (HLA)-matched donor.

[General anesthesia in a patient with idiopathic orthostatic hypotension]. / Allgemeinanästhesie bei einem Patienten mit idiopathischer orthostatischer Hypotonie.

Idiopathic orthostatic hypotension (formerly known as Shy-Drager syndrome) is a multiple system atrophy, which is characterized by autonomic dysregulation. Providing perioperative hemodynamic stability during narcosis is therefore a particular challenge. The effects of general anesthesia on systemic vascular resistance and cardiac output in a patient with idiopathic orthostatic hypotension undergoing retropubic prostatectomy will be reported. In the case presented perioperative hemodynamic stability was achieved by aggressive volume therapy guided by global end-diastolic volume measurement and low-dose catecholamine therapy.

Pediatric related and unrelated cord blood transplantation for malignant diseases.

The use of umbilical or placental donor cord blood transplantation (CBT) in children with malignant and non-malignant diseases has witnessed important progress, mainly because of better cord blood donor choice and patient selection translating into better patient outcome. Approximately 2000 children with malignant diseases (about 75 % with acute leukemias) have been transplanted with a related (n=199) or unrelated CBT (UCBT, n=1663) and reported to Eurocord registry from 1990-2008. Disease-specific studies have been carried out after UCBT for acute lymphoblastic and myeloid leukemia and myelodysplastic syndromes in others to identify the risk factors that may improve outcomes. Outcomes after CBT have been compared with other alternative allogeneic hematopoietic SCT (HSCT) donors. Briefly, after CBT, myeloid engraftment is delayed, acute and chronic GVHD decreased and disease-free survival was not statistically different when compared with HLA identical and other alternative HSCT donor. Therefore, any physician has to carefully evaluate, for each single pediatric patient in need of an allograft, all the possible alternatives in order to choose the best hematopoietic stem cell donor, taking into account type of disease, urgency of transplantation, donor characteristics and center experience. This review will analyze the current results of CBT for pediatric patients with malignant diseases and the advantages and limitations of using this stem cell source.

The Prevention of Post-Partum Relapses with Progestin and Estradiol in Multiple Sclerosis (POPART'MUS) trial: rationale, objectives and state of advancement.

Multiple sclerosis (MS) affects 1 in 1000 people in western countries, mainly women in their childbearing years. It is an autoimmune disease of the central nervous system, which results in a chronic focal inflammatory response with subsequent demyelination and axonal loss. It usually begins with acute episodes of neurological dysfunction, the relapses, followed by periods of partial or complete remission. This relapsing-remitting phase is usually followed by a steady, continuous and irreversible worsening of the neurological dysfunction, which characterizes the progressive phase of the disease. Recent prospective studies reported a significant decline by two-third in the rate of relapses during the third trimester of pregnancy and a significant increase by two-third during the first three months post-partum by comparison to the relapse rate observed during the year prior to the pregnancy. These dramatic changes in the relapse rate occur at a time when impregnation of many substances, among which sexual steroids, is at its highest, before a dramatic decline to the pre-pregnancy levels, immediately following delivery. It may be hypothesized that sexual steroids could exert beneficial effects through a modulation of the immune state with a lowering of the pro-inflammatory lymphocyte responses of the Th1 type and an enhancement of anti-inflammatory responses of the Th2 type. They may also play a direct role in remyelination of central nervous system lesions, as they do in the peripheral nervous system, where progesterone increases the extent of myelin sheath formation after a cryolesion of the male mouse sciatic nerve. The POPART'MUS study is a European, multicentre, randomized, placebo-controlled and double-blind clinical trial, which aims to prevent MS relapses related to the post-partum condition, by administrating high doses of progestin, in combination with endometrial protective doses of estradiol. Treatment is given immediately after delivery and continuously during the first three months post-partum. At present, 126 patients have been enrolled and 107 patients have completed the protocol. Assuming the results of the trial to be positive, this new treatment could be considered in the relapsing-remitting phase of the disease in women afar from pregnancy and post-partum. The trial is registered under the reference NTC00127075.

KIR-ligand incompatibility in the graft-versus-host direction improves outcomes after umbilical cord blood transplantation for acute leukemia.

Donor killer cell immunoglobulin-like receptor (KIR)-ligand incompatibility is associated with decreased relapse incidence (RI) and improved leukemia-free survival (LFS) after haploidentical and HLA-mismatched unrelated hematopoietic stem cell transplantation. We assessed outcomes of 218 patients with acute myeloid leukemia (AML n=94) or acute lymphoblastic leukemia (n=124) in complete remission (CR) who had received a single-unit unrelated cord blood transplant (UCBT) from a KIR-ligand-compatible or -incompatible donor. Grafts were HLA-A, -B or -DRB1 matched (n=21) or mismatched (n=197). Patients and donors were categorized according to their degree of KIR-ligand compatibility in the graft-versus-host direction by determining whether or not they expressed HLA-C group 1 or 2, HLA-Bw4 or HLA-A3/-A11. Both HLA-C/-B KIR-ligand- and HLA-A-A3/-A11 KIR-ligand-incompatible UCBT showed a trend to improved LFS (P=0.09 and P=0.13, respectively). Sixty-nine donor-patient pairs were HLA-A, -B or -C KIR-ligand incompatible and 149 compatible. KIR-ligand-incompatible UCBT showed improved LFS (hazards ratio=2.05, P=0.0016) and overall survival (OS) (hazards ratio=2.0, P=0.004) and decreased RI (hazards ratio=0.53, P=0.05). These results were more evident for AML transplant recipients (2-year LFS and RI with or without KIR-ligand incompatibility 73 versus 38% (P=0.012), and 5 versus 36% (P=0.005), respectively). UCBT for acute leukemia in CR from KIR-ligand-incompatible donors is associated with decreased RI and improved LFS and OS.

Granulocyte colony-stimulating factor for poor graft function after allogeneic stem cell transplantation: 3 days of G-CSF identifies long-term responders.

Poor graft function (PGF) is a frequent cause of morbidity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). To study the value of granulocyte colony-stimulating factor (G-CSF) in PGF, we retrospectively analyzed 81 episodes of PGF in 66 patients transplanted from 01/94 to 01/99 from an HLA-identical sibling (n = 45) or an unrelated (n = 21) donor. Median age was 29 years, 55 patients had malignancies. A total of 11 patients received a CD34+ selected graft. Viral infections (25%), myelotoxic drug (33%), fungal/bacterial infections (14%), and GVHD (31%) were present before PGF diagnosis. Median time from allo-HSCT to PGF was 75 (25-474) days. All patients were treated with G-CSF. In 77/81 episodes, there was a response that was sustained in 57. A total of 27 patients presented an increase of white cell count (WBC) >0.1 x 10(9)/l after 3 days of G-CSF. The 5-year survival was 37% and was significantly better in patients with increased WBC > 0.1 x 10(9)/l after 3 days of G-CSF (65 vs 18%, P < 0.0001). In multivariate analysis, increased WBC > 0.1 x 10(9)/l after 3 days of G-CSF (P = 0.002) was associated with better survival, while BuCy-based conditioning (P = 0.02) and GVHD (P = 0.005) were associated with higher risk of death. In conclusion, hematological response after 3 days with G-CSF predicted a better survival for patients with PGF after allo-SCT.

Comparison of outcomes of unrelated bone marrow and umbilical cord blood transplants in children with acute leukemia.

In order to compare the outcomes of unrelated umbilical cord blood transplants (UCBTs) or bone marrow transplants, 541 children with acute leukemia (AL) transplanted with umbilical cord blood (n = 99), T-cell-depleted unrelated bone marrow transplants (T-UBMT) (n = 180), or nonmanipulated (UBMT) (n = 262), were analyzed in a retrospective multicenter study. Comparisons were performed after adjustment for patient, disease, and transplant variables. The major difference between the 3 groups was the higher number in the UCBT group of HLA mismatches (defined by serology for class I and molecular typing for DRB1). The donor was HLA mismatched in 92% of UCBTs, in 18% of UBMTs, and in 43% of T-UBMTs (P <.001). Other significant differences were observed in pretransplant disease characteristics, preparative regimens, graft-versus-host disease (GVHD) prophylaxis, and number of cells infused. Nonadjusted estimates of 2-year survival and event-free survival rates were 49% and 43%, respectively, in the UBMT group, 41% and 37% in the T-UBMT group, and 35% and 31% in the UCBT group. After adjustment, differences in outcomes appeared in the first 100 days after the transplantation. Compared with UBMT recipients, UCBT recipients had delayed hematopoietic recovery (Hazard ratio [HR] = 0.37; 95% confidence interval [95CI]: 0.27-0.52; P <.001), increased 100 day transplant-related mortality (HR = 2.13; 95CI: 1.20-3.76; P <.01) and decreased acute graft-versus-host disease (aGVHD) (HR = 0.50; 95CI: 0.34-0.73; P <.001). T-UBMT recipients had decreased aGVHD (HR = 0.25; 95CI: 0.17-0.36; P <.0001) and increased risk of relapse (HR = 1.96; 95CI: 1.11-3.45; P =.02). After day 100 posttransplant, the 3 groups achieved similar results in terms of relapse. Chronic GVHD was decreased after T-UBMT (HR = 0.21; 95CI: 0.11-0.37; P <.0001) and UCBT (HR = 0.24; 95CI: 0.01-0.66; P =.002), and overall mortality was higher in T-UBMT recipients (HR = 1.39; 95CI: 0.97-1.99; P <.07). In conclusion, the use of UCBT, as a source of hematopoietic stem cells, is a reasonable option for children with AL lacking an acceptably matched unrelated marrow donor.

Restaging with gallium scan identifies chemosensitive patients and predicts survival of poor-prognosis mediastinal Hodgkin's disease patients.

UNLABELLED: Following treatment of mediastinal Hodgkin's disease (HD), residual masses are frequent and gallium scanning has proven to be of value in the evaluation of their specificity (fibrosis or active disease). This study assessed, for relapse and survival, the predictive value of restaging gallium scan of patients with a residual mass on computed tomography scan after induction chemotherapy. Between 1/89 and 12/97, in 53 newly diagnosed HD patients with a residual mediastinal mass, a gallium scan was performed after chemotherapy (3 or 4 courses) and always before consolidative radiotherapy. Characteristics at diagnosis were: nodular sclerosis histology, 89%; bulky mediastinal disease, 79%; B-symptoms, 51%. RESULTS: gallium scan was positive in 16 patients (30%) and negative in 37 (70%). At median follow-up period of 36 months, freedom-from-progression rate was 86% versus 19% (P<0.0001) for patients with negative vs positive gallium scans, respectively. The 5-year overall survival (OS) rate was 68% and differed significantly (P<0.0001) between negative (91%) and positive (25%) gallium scanning groups. The specificity of gallium scanning was 91% and the sensitivity 72% with a positive predictive value of 81% and a negative predictive value of 86%. Evaluation with gallium scan after induction chemotherapy identifies chemosensitive patients among those with poor-prognosis mediastinal HD. Although relapse may occur in patients with negative gallium scan, a postive gallium scan is highly predictive of failure and poor outcome, and treatment should thus be modified.

Economy of contraction of cardiomyocytes as influenced by different positive inotropic interventions.

In the present study the effects of the novel cardiotonic agent EMD-57033 on contraction and energetic demand of isolated, electrically stimulated cardiomyocytes were investigated and compared with the effects of enhancement of extracellular calcium and of the beta-mimetic isoproterenol. In a specially designed setup [H. Rose, K.H. Strotmann, S. Pöpping, Y. Fischer, D. Kulsch, and H. Kammermeier. Am. J. Physiol. 261 (Heart Circ. Physiol. 30): H1329-H1334, 1991] parameters of contractile behavior and metabolic demand (O2 consumption) of isolated cardiac myocytes were measured. For a given enhancement of contractile performance (cell shortening) the increase in energetic demand (VO2) after application of EMD-57033 were markedly lower than on treatment with elevated extracellular Ca2+ concentration or with isoproterenol. This economization of positive inotropic effects was proposed to be due to two factors. First, stimulation-related ion cycling was only slightly enhanced with marked increase in contraction amplitude after application of EMD-57033. Second, calcium sensitization reflected in a leftward shift of the calcium concentration needed for half-maximum force development could be interpreted to be mediated by modulation of the cross-bridge dynamics of the myofilaments, where reduction of the switch-off rate of the cross bridges and prolongation of their force-generating states were presumed to be involved. Lowered pH (7.0) decreased economy of contraction. EMD-57033 restored contraction amplitude and economy of contraction at lowered pH.

The effect of anoxia on cardiomyocyte glucose transport does not involve an adenosine release or a change in energy state.

The action of anoxia on glucose transport was investigated in isolated resting rat cardiomyocytes. Incubation of these cells in the absence of oxygen for 30 min resulted in a 4- to 5-fold increase in glucose transport (with a lag period of 5-10 min). Up to 40 min of anoxia failed to alter the cellular concentrations of ATP, phosphocreatine, and creatine. Adenosine deaminase (1.5 U/ml), the A1-adenosine receptor antagonist 1,3-diethyl-8-phenylxanthine (1 microM), or the A2-selective antagonist 3,7-dimethyl-1-propargylxanthine (20 microM) had no effect on anoxia-dependent glucose transport. Moreover, adenosine (10-300 microM, added under normoxia) did not stimulate glucose transport. Wortmannin (1 microM) did not influence the effect of anoxia, but completely suppressed that of insulin. On the other hand, the effects of anoxia and insulin were not additive. These results indicate (i) that the effect of anoxia on cardiomyocyte glucose transport is not mediated by a change in energy metabolism, nor by an adenosine release; (ii) that it probably does not involve a phosphatidylinositol 3-kinase, in contrast to the effect of insulin, and (iii) that the signal chains triggered by anoxia or insulin may converge downstream of this enzyme, or, alternatively, that anoxic conditions may impair the action of the hormone.

Effect of a hawthorn extract on contraction and energy turnover of isolated rat cardiomyocytes.

The hawthorn extract LI 132 (crataegus), prepared from leaves and flowers, and standardised to 2.2% flavonoids, was investigated with respect to its effect on (1) the contraction, (2) the energy-turnover and (3) the apparent refractory period (t(ref)) of isolated cardiac myocytes from adult rats. (1) The contractile behaviour of attached myocytes was analyzed by an image processing system. (2) The energy turnover was calculated from the decrease in oxygen content in the myocyte suspension, brought about by cellular respiration. It was differentiated between energy turnover related to cell shortening and that required for ionic transport processes by application of the contraction-inhibiting agent 2,3-butanedione monoxime. (3) The apparent refractory period (t(ref)) was evaluated by pacing the myocytes with increasing stimulation rates and determining the frequency at which failure of single contractions occurred. For these purposes, the myocytes were incubated in a stimulation chamber, which is part of a computer-assisted system allowing to simultaneously evaluate the mechanics and energetics of electrically induced contraction. Within a range of 30-180 microg/ml, the hawthorn extract exhibited a positive inotropic effect on the contraction amplitude accompanied by a moderate increase of energy turnover both for mechanical and ionic processes. In comparison with other positive inotropic interventions, such as application of the beta-adrenergic agonist isoprenaline, or of the cardiac glycoside ouabain (g-strophantin), or elevation of the extracellular Ca++-concentration, the effects of the hawthorn extract were significantly more economical with respect to the energetics of the myocytes. Furthermore the extract prolonged the apparent refractory period in the presence and the absence of isoprenaline, which be indicative for an antiarrhythmic potential.

Fatty-acid peroxidation in relation to trace elements in serum of patients with homozygous sickle-cell anemia and beta-thalassemia: a gas-chromatographic study.

Due mainly to a deeply disturbed iron metabolism, intense production of oxygen-derived free radicals occurs in genetic hemoglobinopathies such as homozygous sickle-cell anemia and beta-thalassemia. Together with impairments in the natural factors involved in oxy-radical detoxication, this results in intense oxidative stress leading to lipid peroxidation in the blood components. In search of peroxidation effects, we undertook a gas chromatographic study of both the total and phospholipid-bound fatty acids in the serum from sickle-cell disease and beta-thalassemia patients. Specific alterations of pathologic origin have been evidenced in the profiles of total and phospholipidic fatty acids, as well as in the elongation-desaturation ratios of the total fatty acids. Results are consistent with lipid peroxidations and fatty-acid biosynthesis disturbances in both diseases, but more severe in thalassemia than in sickle-cell anemia. Increased serum selenium in the latter disease might exert a protective action against lipid peroxidation.

Negative inotropic effects of the new class I antiarrhythmic agents berlafenone and alprafenone on electrically stimulated isolated cardiomyocytes.

Isolated cardiac myocytes from adult rats were used in a stimulation chamber to investigate the negative inotropic effects of propafenone and the new compounds berlafenone (1-2'-biphenyloxy)-3-tert-butylamino-propanol-2-hydrochloride, GK 23 G; CAS 18965-97-4) and alprafenone (1-(4-methylphenyl)-3-[3'-(2-hydroxy-3-tert-pentylaminopropoxy)-4'- methoxyphenyl]-1-propanonhydrochloride, AH 141; CAS 124316-02-5). This chamber is part of a new device that allows the simultaneous evaluation of mechanics and of the energetics of electrically induced contractions of the myocytes. 1. The contractile behaviour of attaches myocytes was analysed by an image processing system using digitized frames of a CCD camera. 2. The metabolic demand for excitation-contraction coupling was calculated from the drop in oxygen tension (registered by a Clark electrode) caused by suspended myocytes when stimulated in the presence of the contraction inhibiting agent 2,3-butanedione monoxime in the stimulation chamber. 3. The apparent refractory period was evaluated by pacing the myocytes with increasing stimulation rates and determining the frequency at which failure of single contractions occurred. All 3 agents produced a reduction in contraction amplitude of the electrically stimulated myocytes with a similar dose-response relationship (IC50 approx. 10 mumol/l). 4 mumol/l berlafenone reduced the contraction amplitude to 62% of control. Under these conditions the energy expenditure of the contracting cells for excitation and excitation-contraction coupling (ion-cycling) was also reduced (77 +/- 17% of control). Since most of this energy is used for Ca2+ (greater than 80%) it may be concluded that a reduced Ca2+ release causes the negative inotropic action of berlafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of water permeability and proteins of erythrocyte membranes in patients with Duchenne muscular dystrophy.

The characteristics of water permeability of erythrocytes from 54 Duchenne muscular dystrophy (DMD) patients and age-matched controls have been determined by a pulse nuclear magnetic resonance (NMR) technique. A decreased permeability of erythrocyte membrane in DMD was definitely found at all temperatures between 15 and 42 degrees C, with normal values for the activation energy of water diffusion. No differences between DMD and control subjects in the pattern of erythrocyte membrane polypeptides separated by two-dimensional electrophoresis could be detected. The findings are discussed in relation to the molecular mechanisms of water diffusion across erythrocyte membrane and the problem of erythrocyte membrane abnormalities in DMD. A new interpretation of erythrocyte membrane alterations is proposed based on the recent findings regarding the molecular pathology of DMD.

Endogenous depression and imipramine levels in the blood.

Approximate determinations of imipramine plus desmethylimipramine levels in the blood made by a method available in routine clinical chemistry laboratories, in 20 nondelusional endogenous depressives after 3 weeks of treatment (mean dose 130 mg/day, SEM 18.05 mg/day) have shown levels ranging from 10 ng/ml to 494 ng/ml. A positive significant correlation between blood levels and percentage change in scores on the Hamilton scale was found (Spearman's O = 0.49 P < 0.05). Patients with levels above 85 ng/ml had a significantly better therapeutic response than patients with levels below 85 ng/ml. Among the 11 nonresponders, 8 had low levels, 2 had intermediate levels, and 1 had the highest level of the study. In a given nonresponder, approximate determination of imipramine plus desmethylimipramine in the blood may be useful.