Indicators of long-term return to work after severe traumatic brain injury: A cohort study.

BACKGROUND: Return to work (RTW) is a major objective in the rehabilitation of individuals with severe traumatic brain injury (TBI). Implications for long-term occupational integration (beyond 5 years) have rarely been studied. OBJECTIVE: The objective was to assess long-term RTW and the associated factors after severe TBI. MATERIAL AND METHODS: Retrospective analysis of a cohort of individuals 16 to 60 years old admitted to hospital after severe TBI from 2005 to 2009 and followed prospectively. Medical and occupational data were collected from medical files and by systematic telephone interview to assess outcome at a minimum of 6 years post-trauma. Factors associated with RTW were investigated by multivariable regression analysis, estimating prevalence ratios (PRs) and 95% confidence intervals (CIs). A proportional hazards model was used to study RTW delay, estimating hazard ratios (HRs). RESULTS: Among the 91 individuals included (mean [SD] age 28.5 [11.3] years; 79% male), 63.7% returned to work after a mean of about 20 months, and 57.1% were still working at the time of the survey. Factors significantly associated with RTW on multivariable analysis were higher educational level (adjusted PR, 1.53; 95% CI, 1.15 to 2.03), absence of motor disability (adjusted PR, 1.82; 1.12 to 2.95) and behavioural disorder (adjusted PR, 1.26; 1.01 to 1.60), as well as disabled worker status (adjusted PR, 1.26; 1.01 to 1.60) (likelihood of the multivariate analysis model 53.1). Delayed RTW was associated with health insurance payments (adjusted HR, 0.40; 95% CI, 0.22 to 0.71), motor disability (adjusted HR, 0.34; 0.15 to 0.76), low educational level (adjusted HR, 2.20; 1.06 to 4.56) and moderate disability on the Extended Glasgow Outcome Scale (adjusted HR, 0.49; 0.27 to 0.91) (likelihood of the multivariate analysis model 335.5). CONCLUSION: Individuals with the most severe TBI are able to RTW and remain in work. This study highlights the multiple determinants involved in RTW and the role of socioenvironmental factors.

Application to proteomics to understand and modify meat quality.

The use of proteomics in the field of meat science has gained in robustness and accuracy. This is consistent with the genomic and bioinformatic tools. Its application to sensorial and technological meat quality traits is discussed as well as the emergence of sanitary and nutritional issue which will grow in a next future.

Distinct metabolism of linoleic and linolenic acids in liver and adipose tissues of finishing Normande cull cows.

Feeding strategies based on the addition of plant lipids rich in polyunsaturated fatty acids (PUFAs) in diets of bovines during the finishing period are common to enhance the nutritional value of meat. However, following rumen biohydrogenations, these FAs could still be metabolised in various tissues/organs involved in the FA metabolism such as the liver and adipose tissues (ATs), thus affecting their subsequent deposition in muscles. In this context, the objective of this study was to characterise the various metabolic pathways of linoleic acid (LA) and α-linolenic acid (ALA) in the liver and ATs (subcutaneous (SC) and inter-muscular (IM)) of Normande cull cows fed a diet supplemented (LR) or not (C) with extruded linseeds and rapeseeds, using the ex vivo incubated tissue slice method. Hepatic uptake of both FAs was higher with the LR than with the C diet (P = 0.02). For the two diets, ALA uptake was higher than that of LA (+46%, P = 0.04). ALA was much more degraded by ß-oxidation (>50% of ALA present in cells) than LA (∼27%) with both diets (P = 0.015). Whatever the diet, ALA was not converted into longer and/or more unsaturated FA, whereas about 14% of LA was converted into 20:4n-6. The intensity of the esterification pathway was higher (+70%, P = 0.004) with the LR than with the C diet, for both FAs. Hepatic secretion of ALA as part of the very-low-density lipoprotein particles was lower than that of LA (-58% and -23% for C and LR diets respectively, P = 0.02). In SC and IM ATs, dietary lipid supplementation did not alter metabolic pathways of LA and ALA. They were efficiently taken up by ATs (>68% of FA present in the medium), with uptake being higher for IM than for SC AT (+12%, P = 0.01). Moreover, LA uptake by ATs was higher than ALA uptake (+10.7%, P = 0.027). Both FAs were mainly esterified (>97% of FA present in adipocytes) into neutral lipids (>85% of esterified FA). Around 9.5% of LA was converted into 20:4n-6, whereas only around 1.3% of ALA was converted into 20:5n-3. We concluded that, in our experimental conditions, liver was highly active in ALA catabolism limiting its subsequent deposition in muscles. However, bovine liver and ATs were inefficient at converting ALA into long-chain n-3 PUFA, but actively converted LA into 20:4n-6.

Effects of supplementation of maize silage diets with extruded linseed, vitamin E and plant extracts rich in polyphenols, and morning v. evening milking on milk fatty acid profiles in Holstein and Montbéliarde cows.

The aim of this study was to evaluate the effects on dairy performance and milk fatty acid (FA) composition of (i) supplementation with extruded linseed (EL), (ii) supplementation with synthetic or natural antioxidants, namely vitamin E and plant extracts rich in polyphenols (PERP), (iii) cow breed (Holstein v. Montbéliarde) and (iv) time of milking (morning v. evening). After a 3-week pre-experimental period 24 lactating cows (12 Holstein and 12 Montbéliarde) were divided up into four groups of six cows: the first group received a daily control diet (diet C) based on maize silage. The second group received the same diet supplemented with EL (diet EL, fat level approximately 5% of dietary dry matter (DM)). The third group received the EL diet plus 375 IU/kg diet DM of vitamin E (diet ELE). The fourth group received the ELE diet plus 10 g/kg diet DM of a PERP mixture (diet ELEP). Compared with the diet C, feeding EL-rich diets led to lower concentrations of total saturated FA (SFA) and higher concentrations of stearic and oleic acids, each trans and cis isomer of 18:1 (except c12-18:1), non-conjugated isomers of 18:2, some isomers (c9t11-, c9c11- and t11t13-) of conjugated linoleic acid (CLA), and 18:3n-3. The vitamin E supplementation had no effect on milk yield, milk fat or protein percentage and only moderate effects on milk concentrations of FA (increase in 16:0, decreases in 18:0 and t6/7/8-18:1). The addition of PERP to vitamin E did not modify milk yield or composition and slightly altered milk FA composition (decrease in total saturated FA (SFA) and increase in monounsaturated FA (MUFA)). The minor effects of vitamin E may be partly linked to the fact that no milk fat depression occurred with the EL diet. During both periods the Holstein cows had higher milk production, milk fat and protein yields, and milk percentages of 4:0 and 18:3n-3, and lower percentages of odd-branched chain FA (OBCFA) than the Montbéliarde cows. During the experimental period the Holstein cows had lower percentages of total cis 18:1, and c9,c11-CLA, and higher percentages of 6:0, 8:0, t12-, t16/c14- and t13/14-18:1, and 18:2n-6 than Montbéliarde cows because of several significant interactions between breed and diet. Also, the total SFA percentage was higher for morning than for evening milkings, whereas those of MUFA, total cis 18:1, OBCFA and 18:2n-6 were lower. Extruded linseed supplementation had higher effect on milk FA composition than antioxidants, breed or time of milking.

Plant polyphenols associated with vitamin E can reduce plasma lipoperoxidation in dairy cows given n-3 polyunsaturated fatty acids.

Diets rich in n-3 polyunsaturated fatty acids (PUFA) improve the nutritional value of ruminant products but also increase the risk of lipoperoxidation in plasma and tissues. The relative effectiveness of dietary antioxidants such as vitamin E (vit E) given alone or with plant extracts rich in polyphenols (PERP) containing rosemary, grape, citrus, and marigold was investigated in the plasma of mid-lactation dairy cows given diets enriched in 18:3 n-3. For a 30-d period, the animals were given a maize silage-based diet (control group C, n = 6) or the same basal diet supplemented with extruded linseed rich in 18:3 n-3 [50 g of oil/kg of diet dry matter (DM); group L, n = 6], extruded linseed + vit E (375 international units/kg of diet DM; 7,500 IU/cow per day; group LE, n = 6), or extruded linseed + vit E + PERP (10 g/kg of diet DM; group LEP, n = 5). Plasma susceptibility to lipoperoxidation was evaluated using in vitro parameters of conjugated diene formation (lag phase and maximum oxidation rate). Plasma indicators of lipoperoxidation and antioxidant status were analyzed in the 4 experimental groups as well as the fatty acid (FA) composition of total plasma lipids. At d 30, group L significantly increased plasma cholesterol esters (+57%) and phospholipids (+35%) compared with group C. It also increased plasma n-3 PUFA (4.7-fold increase) to the detriment of n-6 PUFA (-30%), leading to a higher peroxidizability index (+20%). Plasma in vitro lipoperoxidation was higher in group L (rich in 18:3 n-3) than in group C. Vitamin E alone had no effect on lipoperoxidation, whereas vit E in association with PERP lowered lipoperoxidation by increasing the resistance time against peroxidation (+47%) and by decreasing the oxidation rate (-48%) compared with group L at d 30. Surprisingly, in vivo plasma lipoperoxidation estimated by the plasma level of the major lipoperoxidation product (malondialdehyde) was not significantly increased in group L. This study shows, for the first time, that PERP supplied in association with vit E were able to reduce lipoperoxidation in lactating cows given a diet rich in 18:3 n-3, thereby helping to protect cows against the deleterious consequences of lipoperoxidation and potentially ensuring antioxidant potential for 18:3 n-3-enriched dairy products.

[Differenciated function: prospects for the nursing profession in Belgium]. / Différenciation de fonction: quelles perspectives dans le cadre de la profession infirmière en Belgique?

The hospital and medical contexts are undergoing profound change. All professions must follow this evolution, in particular, the nurse profession. The care offer and the care demand are unbalanced: the clinical situations become more complex and the staff is insufficient quantity. The function differentiation can be a solution for the nurse profession. The aim of this study is to evaluate the feasibility of the function differentiation for the nurse profession in Belgium. Based on 364 "patient situations a derived from hospital experiences, required activities and competencies are depicted by more 200 nurses; the complexity of each competency is also evaluated by standardized scales of complexity. A cluster analysis is performed in order to pool all identified competencies. For each department, four groups are identified; each group is relevant on the statistical level but also on the clinical level. The results speak for a function differentiation in a vertical way, but not in a horizontal way between several different departments, in particular for the competencies needed a clinical judgement because these competencies are too specific by department, In conclusion, a function differentiation can be envisaged for the nurse profession in Belgium. Several models from foreign countries set an example for the practical modalities. Several advices in terms of education, lawful framework, interdisciplinary, and collaboration are formulated

[Seasonal outbreak of enteroviral meningitis during summer 2005: experience of a French pediatric unit]. / Epidémie estivale de méningites à entérovirus en 2005: expérience d'un service de pédiatrie générale.

OBJECTIVE: To describe the clinical and biological characteristics of children presenting with enteroviral (EV) meningitis in a French paediatric unit during summer 2005. METHODS: Retrospective study of children with EV meningitis from May to September 2005, diagnosed by PCR and/or viral culture in cerebrospinal fluid (CSF), serum or throat. RESULTS: We reported 99 cases of EV meningitis (96 confirmed and 3 probable). The sex ratio was 2/1, and the median age was 5 years. Peak incidence was reached during the second week of July. The predominant symptom was meningism. ENT (16%), digestive (10%), cutaneous (15%) or respiratory (4%) symptoms were rare. Blood leucocyte count found a predominance of neutrophils (73%), and lymphopenia in half of the children. The mean value of CRP was 25,5 mg/l. The median leukocyte count in CSF was 65 cells/mm(3), with a prevalence of neutrophils in 60% of cases. Pleiocytosis was absent in 20 children. CSF protein level was increased in 20% of cases. The rate of hospitalization was 57,5%. Intravenous antibiotic treatment, initiated among 18 patients, was stopped in 66,6% of the cases on reception of PCR result. The latter result was obtained in 2,3 days on average. CONCLUSION: The epidemic of 2005 EV meningitis was as widespread as that of summer 2000. Characteristics of these meningitis are strong proportion of CSF without pleiocytose and high prevalence of neutrophils in blood and CSF.

[Pharmacological treatment of hypercholesterolaemia in primary prevention. The use of the different sources of information]. / Centre académique de Médecine générale a la Katholieke universitieit van Leuven (KUL).

In the first two articles of this series devoted to Evidence-Based Medicine, we have shown how to translate a clinical problem in a well formulated question and how to derive search terms from the PICO. In this article, we describe in more detail the different sources of information and how to use them. The strategy will be illustrated by answering the question whether it should be recommended to treat hypercholesterolaemia in a young woman without cardiovascular risk factors. In a following article, we will show how to adapt a search strategy to a specific question or PICO.

Antitumor response against myeloma cells by immunization with mouse syngenic dendritoma.

In order to generate an immune response against myeloma cells in an homogenous murine model, a stable hybrid cell line (DCSp) was established through the syngenic fusion between mouse dendritic cells (DC) and mouse Sp2/0 myeloma cells. DCSp cells behaved as potent T cell stimulators and were able to induce Sp2/0 specific cytotoxicity. When mice were immunized with irradiated hybrids before SP2/0 injection, they exhibited a significantly higher rate of survival as compared with controls. When tumors were detected, their emergence was not delayed, and time elapsed between tumor clinical perception and death remained unchanged. A humoral immune response was also always associated. We assume that this stable dendritoma cell line can be considered a valuable tool for myeloma studies in an homogenous mouse model. The efficiency of dendritoma as a weapon against tumor cells and the benefit of syngeny in experimental models are discussed.

Adecuación de las restricciones físicas y farmacológicas en los ancianos institucionalizados: estudio comparativo en Québec y la Suiza Romanda, con implicaciones en nuestro medio / Appropriateness of the use of physical restraints and psychotropic medication in institutionalised older people: comparative study in Quebec and French Switzerland. Applicability to Spain

Objetivo: analizar la variabilidad dentro y entre diferentes países en el empleo de restricciones físicas y fármacos psicotropos en mayores de 65 años institucionalizados en centros de Québec y la Suiza Romanda, y estudiar la aplicabilidad de estos resultados a futuros estudios en nuestro medio. Material y método: se analizan los datos de los individuos institucionalizados en Québec y la zona francófona de Suiza mediante el sistema de información denominado PLAISIR, utilizado en dichos centros para la gestión y el análisis de los recursos financieros. Se obtienen datos de todos los ingresos habidos en 1998 en 179 instituciones de Québec (n = 8.183) y en 250 residencias de Suiza (n = 7.592). Las restricciones físicas se clasifican en fijas y móviles. A través de las Defined Daily Doses se codifica la prescripción diaria y semanal de psicotropos. Se determina la prevalencia de cada uno de los medios físicos y farmacológicos y, posteriormente, se calcula un índice de pertinencia de empleo de cada una de ellas por un método de ajuste indirecto. Mediante el análisis de regresión logística se estiman los valores esperados de uso de las diferentes restricciones en función del estado de salud y la situación funcional de los residentes. Resultados: la proporción de residentes con dependencia de otras personas es elevada en ambas regiones, y alcanza un 80% en las instituciones suizas y un 90% en las canadienses. Se observa una alta variabilidad en el empleo de los diferentes métodos restrictivos, tanto entre países como entre instituciones: los psicotropos se prescriben más en Suiza (78%) que en Québec (67%), mientras que las restricciones físicas se usan más en Québec (76%) que en Suiza (40%). La adecuación de su uso varía de forma importante y no puede atribuirse únicamente a las características de los residentes Conclusiones: la alta variabilidad observada en la adecuación del empleo de diferentes medios restrictivos, físicos y farmacológicos refleja probablemente la ausencia de aplicación de estándares de calidad y/o una legislación insuficiente, tanto en Québec como en Suiza. Estos resultados ilustran un método útil para iniciar la investigación sobre la prevalencia y la adecuación del uso de estos métodos en España

Objective: a) to examine intra- and inter-country variability in the use of physical restraints and psychotropic medication in institutionalised people older than 65 in Quebec and in Romande, Switzerland, and b) to study the applicability of the results to future studies in Spain. Material and method: data were collected through PLAISIR, an information system on persons institutionalised in Quebec and French-speaking Switzerland used for financing and planning, resource allocation and management, utilisation control and quality assurance. Data were obtained from all new admissions to 179 institutions in Quebec (n = 8183) and to 250 institutions in Switzerland (n = 7592) in 1998. Physical restraints were classified into fixed and mobile. Daily and weekly uses of psychotropic medication were coded by defined daily doses. The prevalence of the use of physical restraints and psychotropic medication were estimated and an index of the appropriateness of the use of each was calculated by an indirect adjustment method. A logistic regression model on the use of both types of restriction based on residents’ health and functional status was calculated to estimate expected values of use. Results: the rate of dependency was high in residents of both regions. Approximately 80% of residents in French Switzerland and 90% of those in Quebec were dependent for activities of daily living. Intra- and inter-country variability in the use of restrictions is high: psychotropic medication was more often used in French Switzerland (78%) than in Quebec (67%), while physical restraints were more often used in Quebec (76%) than in French Switzerland (40%). The appropriateness of use varied widely within both regions and cannot be fully explained by the characteristics of the residents. Conclusions: the high variability in the use of physical restraints and psychotropic medication may be a result of the absence of standards of quality and/or legislation both in Quebec and in French Switzerland. This research illustrates a method that could be useful to investigate the prevalence and appropriateness of the use of these restriction methods in Spain

Long-lasting rat growth enhancement by an immunoregulating synthetic peptide.

We have studied the long-lasting effects on rat weight gain of an active immunization with a peptide construction consisting of the covalent linkage of the 104-113 GH sequence to the 323-339 sequence of ovalbumin and to adjuvant muramyl dipeptide (MDP). The 104-113 GH sequence has already been identified as a potential epitope capable of enhancing growth hormome (GH) activity when complexed with the specific antibodies. Our results show that: a) 104-113 peptide antibodies after reacting with the endogenous GH produced a weight gain up to 7% higher than that observed in unimmunized rats; and b) the position of the adjuvant sequence in the molecule was critical for the immune response. Antibodies elicited in hypophysectomised rats had no effect on weight gain, thus confirming that the increase in hormonal activity is actually linked to the binding of specific peptide antibodies to endogenous GH.

Cervical artery dissections.

Cervical artery dissection (CAD) accounts for up to one fifth of ischemic strokes occurring before 45 years. Their increasing recognition is probably due to an increased clinical awareness of this condition in patients with painful ischemic events. The internal carotid artery is the most commonly affected vessel. Cerebral ischemia is the most serious consequence of a CAD. It may be due to hemodynamic factors or emboli. The enlargement of the artery may lead to a direct compression of the lower cranial nerves. CAD typically occurs in young adults with a mean age of 40 years with a male:female ratio of 1.5. After exclusion of traumatic cases, the average annual incidence rate of CAD is 2.6 per 100,000, but the reported incidence figures in the literature are likely to be an underestimation of the incidence of CAD. A spontaneous dissection is assumed when no or only minor trauma preceded the onset. However, the differentiation between spontaneous and traumatic dissections is artificial because of a continuum between both forms. The pathogenesis of dissections remains unknown in most cases. However, traumas and primary diseases of the arterial wall are the main predisposing factors. The clinical presentation of spontaneous dissections of the internal carotid artery includes cerebral ischemia, cervical or cranial pain, Horner's syndrome and cranial nerve palsy; CAD may also be silent. Brainstem ischemic deficits and occipital pain are the most common findings in vertebral artery dissections, but these features may be biased because the most benign and the most severe cases may escape detection. The favorable natural history of CAD emphasizes the need for a noninvasive approach to the detection, monitoring and follow-up. This noninvasive approach can be obtained by means of CT scan, MRI, magnetic resonance angiography and ultrasonography, although angiography remains the gold standard for the diagnosis of arterial dissections. Follow-up studies suggest a fairly good overall prognosis in adults and in children. In many centers, CAD are treated by heparin at the acute stage, although the benefit of such a potentially dangerous treatment has never been proven by a randomized trial.

Cranial nerve palsies due to internal carotid artery dissection: seven cases.

Cranial nerve palsies are rare complications of internal carotid artery (ICA) dissections. The aim of this study is to evaluate the incidence of cranial nerve palsies in consecutive patients with ICA dissection and to describe clinical and radiological characteristics and their evolution over time. This study was conducted in 52 consecutive patients with dissection of the ICA. We have analyzed clinical data of patients with cranial nerve palsy as complication of ICA dissection. We defined ICA dissection as angiographic evidence of a string sign, double lumen, or internal flaps or visualization on magnetic resonance imaging (MRI) or computed tomographic scans of an enlarged arterial wall due to the hematoma. Of 52 consecutive patients with ICA dissection 7 had cranial nerve palsies: 2 had an involvement of the Vth cranial nerve and 5 had lower cranial nerve palsies. Five patients totally recovered while 2 did not after a 2 to 10-month period. The frequency of cranial nerve palsies associated with ICA dissection is higher in our study than in those of the literature. Many patients presenting with cranial nerve palsies due to ICA dissection without any ischemic event are probably not referred to stroke units. Angiography is less sensitive than cervical MRI to detect such patients. Cranial nerve palsies could either be due to compression by the enlarged ICA wall or an ischemia of the nerve.

Two monoclonal antibodies identify antigens preferentially expressed on normal human breast cells versus breast cancer cells.

In order to obtain antibodies with specificity toward normal mammary epithelial antigenic determinants, we immunized BALB/c mice with normal milk cells and screened the hybridomas against an undifferentiated breast cancer cell line H466B, peripheral blood lymphocytes and normal fibroblasts. Two hybridomas were generated, which produced BA6 (IgG1) and CA4 (IgM) monoclonal antibodies (MAbs). These MAbs did not react with 5 breast cancer cell lines. In cryostat sections of normal human breast tissue, BA6 was reactive with 6/6 and CA4 was reactive with 12/13 specimens both showing an apical staining of epithelial cells. Conversely staining of malignant cells in breast cancer biopsies was observed in 4/33 specimens with BA6 and in 4/19 specimens with CA4. Computerized image analysis (SAMBA) of immunostained sections showed homogeneous distribution of staining, with a high percentage of stained cell surfaces in normal breast (mean percentages of positive surfaces : BA6 : 75% and CA4 : 82%) while, in malignant samples, staining was heterogeneous, with a mean percentage of positive surface of 25% for BA6 and 12% for CA4. Both MAbs reacted strongly with human milk fat globule membranes (HMFGM) and skimmed milk. FPLC size exclusion chromatography of skimmed milk showed that CA4 and BA6 reactive materials eluted in distinct peaks in high molecular weight ranges. Electrophoretic separation of HMFGM followed by CA4 staining detected a high molecular weight reactive band (Mr 380-600 kDa). CA4 and BA6 reactivity was reduced by protease treatment of the antigen but was not affected by neuraminidase digestion, by methanol extraction or by Na-metaperiodate oxidation. After perchloric acid treatment of HMFGM, BA6 activity was lost while the CA4 activity was found in the soluble fraction. The results reported suggest that the two MAbs identify two distinct novel epitopes of normal breast cells.

[The participation in sports of diabetic children. A survey in the Rouen region]. / La pratique du sport chez l'enfant diabétique. Enquête dans la région rouennaise.

The purpose of this survey conducted during the 1987 academic year was to collect information on the participation in sports, whether at school or in athletic clubs, of 63 children followed on an outpatient basis for diabetes mellitus and to determine what steps are effectively taken by these children to prevent hypoglycemia. Simultaneously, the participation in sports of 200 children seen in a surgical outpatient clinic for any reason was determined. The data collected demonstrated that the diabetic children participated as actively as non-diabetic children in athletics at school and, in addition, were likely to participate in out-of-school non-compulsory sports (40% versus 27%). Approximately two out of three diabetic children reported attempting to prevent hypoglycemia during sports at school by an intake of carbohydrates before or after the activity and/or by a reduction in the dose of insulin acting during the activity, with variable results. Results suggested that hypoglycemic episodes tended to be overtreated, perhaps in part because the teachers were apprehensive about the possible negative effects of hypoglycemia. During out-of-school non-compulsory athletic activities, especially competitive sports, preventive measures against hypoglycemia were consistently taken and diary results seemed to improve steadily in patients who trained regularly several times a week. Lastly, in the population studied no correlation was found between the time spent every week participating in sports and glycated hemoglobin levels.

Nonmetastatic tumor cells acquire metastatic properties following somatic hybridization with normal cells.

Somatic cell hybridization between nonmetastatic tumor cells and normal cells of the lymphoreticular system results in hybrid cells manifesting metastatic properties of defined target organ specificity. Thus, fusion of the nonmetastatic BALB/c originated NSI plasmacytoma with C57BL B lymphocytes resulted in hybridomas, each of which were metastatic. Of 10 hybridomas, 7 generated metastases in the spleen and liver, whereas 3 generated liver metastases. The generation of liver metastases by hybridomas which homed to both spleen and liver, but not by those which homed to the liver only, was controlled by the spleen. The acquisition of metastatic properties via somatic cell fusion seems to represent a general principle, in which the normal partner determines the target organ specificity for the metastatic growth. Thus, fusion of SP2/O myeloma cells with syngeneic B lymphocytes also resulted in a hybrid cell metastasizing to the spleen and liver, yet a somatic hybrid between NSI and a macrophage or dendritic-like cell metastasized to the lung. Cell surface molecules encoded by the genome of the normal partner was demonstrated to control the target organ specificity: antibodies against MHC-encoded antigens of the normal B cell partner prevented the generation of metastases by hybridomas metastasizing to the spleen and liver, but not by those metastasizing to the liver only. This is in accordance with the function of MHC molecules on lymphocytes in controlling their homing to lymphoid organs. Hybridomas of T cell lymphomas also manifested metastatic properties. Analysis of the cell surface Thy-1 antigens of a hybridoma (DCH10), produced via somatic fusion between BW5145 lymphoma and a putative macrophage cell indicated that cells of liver metastases (DCH10-Li) generated by the hybrid cells might have undergone further somatic cell fusion in vivo with host (T?) cells. These cells have acquired new metastatic properties, generating metastases in spleen, liver and kidneys. In fact, even the inoculation of the parental BW lymphoma cells resulted in a case of liver metastasis (BW-Li). Such BW-Li cells, upon reinoculation, also generated metastases in the spleen, liver and kidneys. Analysis of the Thyl phenotype indicated that BW-Li cells may also have undergone somatic cell fusion in vivo with host (T?) cells, resulting in the acquisition of metastatic properties. The pattern of cell-cell interactions (adhesion, infiltration) with liver cell monolayers of BW-Li cells and of DCH10-Li (T-cell lymphomas) was identical, and differed from cells of liver metastases of the myeloma-B cell hybridomas which might be based on responses to liver growth signals.(ABSTRACT TRUNCATED AT 400 WORDS)