Posttraumatic stress disorder in peers of adolescent suicide victims: predisposing factors and phenomenology

OBJECTIVE

To examine the factors predisposing to posttraumatic stress disorder (PTSD) in peers of adolescent suicide victims.

METHOD

One hundred forty-six adolescents who were the friends of 26 suicide victims were studied. Five percent (n = 8) developed PTSD after exposure to suicide. These 8 subjects with PTSD were compared to the remainder of the exposed subjects (n = 138).

RESULTS

Subjects with PTSD were more likely than those without PTSD to have had a history of substance abuse, agoraphobia, and suicide attempts. Subjects who developed PTSD were more likely to have developed a new-onset depression, to have more severe grief, and to have been closer to the suicide victim. Subjects with PTSD tended to have more severe exposure to suicide and came from discordant households with a history of disruptions in key relationships. The 8 subjects who developed PTSD were compared to 38 subjects who developed new-onset depression but not PTSD. Those with PTSD were more likely to have had past substance abuse, prior suicide attempts, family history of panic disorder, a history of parent-child disruption, and a history of loss. Symptoms of intrusive visual images, hypervigilance, and avoidance of reminders discriminated subjects who had PTSD from new-onset depressives without PTSD.

CONCLUSIONS

PTSD is an expectable outcome in youth exposed to suicide. Further work is required to differentiate symptoms of depression from PTSD.

Systemic antitumor effects of electrochemotherapy combined with histoincompatible cells secreting interleukin-2

Electrochemotherapy is an antitumor treatment that combines a cytotoxic drug with the local administration of electric pulses delivered at the tumor site. We previously found that in mice the cure rate of subcutaneous transplanted tumors treated by electrochemotherapy is increased by repeated systemic interleukin-2 (IL-2) injections. Moreover, histoincompatible cells engineered to secrete IL-2 allow the rejection of syngeneic tumor cells when both cells are inoculated together. In this study of preestablished tumors in mice we show that after electrochemotherapy, delayed peritumoral injections of histoincompatible IL-2-producing cells result in the cure of almost all the tumors. Moreover, this combined local treatment leads to cures of untreated, contralaterally transplanted tumors. This systemic antitumor immunity also resulted in complete protection of the cured mice against further inocula of the tumor cells. These results, which were obtained using allogeneic as well as xenogeneic IL-2-secreting cells, suggest that electrochemotherapy combined with such cellular immunotherapy might be a useful approach for the treatment of metastasizing cancers.

Human parvovirus B19 serology with recombinant VP1 and VP2 antigens: diagnosis of acute infections by detecting B19-specific IgM and IgA antibodies

BACKGROUND

The availability of immunoassays for the laboratory diagnosis of human parvovirus B19 (B19) infection, which is commonly associated with erythema infectiosum in children and arthropathy and arthralgia in adults has been hampered by the lack of native B19 antigen. The production of abundant supplies of recombinant (r) B19 proteins, through the cloning of the B19 genome into expression vectors, has led to a proliferation of assays for detecting B19-specific antibodies.

OBJECTIVES

This study was undertaken to evaluate serological assays for detecting B19-specific IgM and IgA antibodies using rVP1 and rVP2 B19 viral coat proteins. Their suitability in the diagnosis of acute B19 infections and the incidence of non-specific reactivity were determined.

STUDY DESIGN

A panel of sera consisting of B19-specific IgM-positive and -negative samples was tested for B19-specific IgM and IgA antibodies in an indirect IFA using rVP1 antigen. These samples and a further panel collected from patients with other virus infections and samples containing rheumatoid factor were tested for B19-specific IgM in an antibody-capture ELISA and an indirect ELISA, both of which utilized rVP2 antigen.

RESULTS

Data from the two ELISAs using rVP2 antigen and the IFA with rVP1 antigen all showed significant correlation (P >/= 0.001) with a reference RIA using native B19 antigen. Non-specific reactions were observed with Paul-Bunnell-positive and rubella virus-specific IgM antibody-positive sera in the ELISAs but not in the IFA. B19-specific IgA antibodies were detected in all sera containing B19-specific IgM antibodies but were also found in a small number of sera collected from healthy blood donors with no history of recent B19 infection.

CONCLUSION

This study demonstrates the usefulness of assays employing rVP1 and rVP2 B19 antigens for detecting B19-specific antibodies. The use of IgM-specific ELISAs allows the processing of large numbers of samples and the absence of non-specific reactivity in the IFA may indicate a role for this assay as a confirmatory test.

Ly-49-independent inhibition of natural killer cell-mediated cytotoxicity by a soluble major histocompatibility complex class I molecule

Natural killer (NK) cells lyse their targets in a non-major histocompatibility complex (MHC)-restricted manner, and the cytotoxicity can be inhibited by a number of MHC class I allele products, suggesting that NK cells may have a "positive receptor" that recognizes the target and a "negative receptor" that receives an inhibitory signal from class I. Since negative receptors could also exert their effect by masking a positive ligand, we have determined whether there may be a direct interaction between class I and an NK surface receptor by measuring cytotoxicity in the presence of a soluble class I molecule, Kd. Soluble Kd at micromolar concentrations could efficiently block NK cell cytotoxicity, suggesting that class I has a direct effect on cytotoxicity, rather than masking another target cell ligand. Inhibition required that Kd be at least divalent, probably because of its higher affinity or its ability to cross-link the NK surface receptor. In addition, the effect was independent of the peptide used to load Kd, and there was inhibition of cytotoxicity of NK cells derived from either H-2d or H-2b mice. Finally, depletion of NK cells expressing Ly-49 had no effect on the specific inhibition by Kd, raising the possibility that NK cells are endowed with additional negative receptors besides Ly-49. Taken together, these results suggest that there may be a family of NK receptors recognizing different class I alleles, which can receive negative signals by directly binding to class I on the target cell surface.

Improvements in volumetric quantification of circumscribed hepatic lesions by three dimensional sonography

The size of hepatic tumors is commonly estimated by ultrasound as well as by computed tomography by measuring the three diameters followed by computing of the volume by applicating the ellipsoid formula. Using the new technique of three-dimensional-sonography it is possible to perform volume measurement by computer-linked planimetry. Initial tests with water filled balloons of defined volume revealed the accuracy (mean error of 3.0%) and high reproducibility (low intra- and inter-observer variance) of the method applied by one investigator (intraindividual SD +/- 1.3%) as well as by four different investigators (interindividual SD +/- 2.1%). Circumscribed hepatic lesions of 63 patients were investigated by using conventional sonography (ellipsoid formula), computed tomography (ellipsoid formula) and three-dimensional-sonography (ellipsoid formula, ortrip, planimetry). As a volume of reference a mathematical approximation for infinite sonographical slices (planimetry) of a very well circumscribed hemangioma of the liver was defined. Based on these results a mean error of -6% (SD +/- 39%) was determined for conventional sonography. For computed tomography a mean error of 2+ (SD +/- 35%) was found, for three-dimensional-sonography that figure was -6% (SD +/- 5%). Follow up investigations can only demonstrate significant alterations of volume when the SD-interval is exceeded. Therefore, three-dimensional-sonography provides a more sensitive and reliable recognition of volumetric changes of liver tumors than conventional sonography or computed tomography does.

Suicide in affectively ill adolescents: a case-control study

Sixty-three adolescent suicide victims with a history of affective illness were compared to 23 adolescent community controls with a lifetime history of affective illness, using a case-control design. Suicide victims were more likely to have had major depression, comorbid substance abuse, a past suicide attempt, family history of major depression, treatment with a tricyclic antidepressant, history of legal problems, and a handgun available in the home. There was a non-significant trend for bipolar depression to convey a higher risk for completed suicide than unipolar depression. Recommendations for the prevention of suicide among those with early onset affective illness are discussed in light of these findings.

Effect of tyrosine kinase inhibitors on islets of Langerhans: evidence for tyrosine kinases in the regulation of insulin secretion

In order to determine if tyrosine kinase activation is involved in the changes in islet function, the effect of tyrosine kinase inhibitors on insulin secretion and islet cell proliferation was examined in cultured islets of Langerhans. When islets were exposed to 100 microM genistein or 2 microM herbimycin A, large 5- to 10-fold increases in insulin secretion were observed. The effect on insulin secretion was detected within 1 hr and was maintained for at least 4 days. The glucose sensitivity of islets exposed to genistein was dramatically increased as demonstrated by a shift of the glucose-dose response curve to lower glucose concentrations. In contrast, islet cell proliferation was dramatically reduced in the presence of these tyrosine kinase inhibitors in the absence or presence of PRL. These very large changes observed in islets suggest that tyrosine kinases may have important roles in the regulation of beta-cell function.

Familial risk factors for adolescent suicide: a case-control study

Sixty-seven adolescent suicide victims and 67 demographically matched living controls were compared as to family constellation, familial stressors and familial loading for psychopathology. Suicide victims were less likely to have lived with both biological parents, were more likely to be exposed to stressors such as parent-child discord, physical abuse and residential instability and showed greater familial loading for depression and substance abuse. Multivariate analyses showed that family history of both depression and substance abuse and lifetime history of parent-child discord were most closely associated with adolescent suicide. Children who are the offspring of parents with depression or substance abuse should be psychiatrically screened. Family interventions to decrease discord may also be helpful in decreasing the risk of adolescent suicide.

Risk factors for completed suicide among adolescents with a lifetime history of substance abuse: a case-control study

The risk factors for suicide in adolescents with substance abuse were assessed by comparing 23 adolescent suicide victims and 12 community controls with a lifetime history of definite or probable DSM-III substance abuse. Suicide victims were more likely than controls to show the following risk factors: active substance abuse, comorbid major depression, suicidal ideation within the past week, family history of depression and substance abuse, legal problems and presence of a handgun in the home. Recommendations for the identification and prevention of suicide among substance-abusing youth on the basis of these findings are presented.

Effects of steroid and lactogenic hormones on islets of Langerhans: a new hypothesis for the role of pregnancy steroids in the adaptation of islets to pregnancy

Adaptive changes that occur in islets of Langerhans during pregnancy include enhanced insulin secretion, insulin synthesis, beta-cell proliferation, gap-junctional coupling among beta-cells, and glucose oxidation. We have determined that elevated lactogenic activity is directly responsible for these changes in beta-cell function. Recently, we showed that two of the principal adaptive characteristics (insulin secretion and beta-cell proliferation) of rat pregnancy peaked on day 15 and returned to control levels by day 20. As placental lactogen remains elevated during late gestation, it was of interest to determine whether pregnancy steroids could reverse the effects of lactogen on islets. In this study, rat islets were cultured with progesterone, estradiol, rat PRL (rPRL), or combinations of these hormones (progesterone and rPRL, estradiol and rPRL, or progesterone and estradiol and rPRL). Insulin secretion was examined for 8 days, and beta-cell proliferation by 2-bromo-5'-deoxyuridine (BrdU) incorporation on days 4 and 8. rPRL treatment resulted in a time-dependent increase in insulin secretion that was 3-fold greater than that from control islets by day 8. Progesterone and estradiol had minimal effects on insulin secretion. Estradiol had no effect on the increased insulin secretion observed with rPRL during the first 6 days and a small inhibitory effect on days 7 and 8. Although progesterone treatment had no effect on the increased insulin secretion induced by rPRL during the first 3 days, it subsequently resulted in a decline in insulin secretion to that from control islets. The combination of progesterone and estradiol was more effective than either steroid by itself in reversing the effects of rPRL on insulin secretion. Similar results were obtained in the BrdU labeling experiments: 1) a 7-fold increase in the number of BrdU-labeled nuclei per islet was observed after culture in the presence of rPRL; and 2) estradiol had a small inhibitory effect on the increased BrdU labeling observed with rPRL; however, 3) progesterone completely reversed the effect of rPRL on islet beta-cell division. These results demonstrate that progesterone counterregulates the effects of PRL on insulin secretion and islet beta-cell division. The temporal changes observed in islets in vitro under the influence of PRL and progesterone mimic those seen in islets during pregnancy. We conclude that progesterone, which increases in the later stages of gestation, is the primary hormone responsible for counteracting the stimulatory effects of elevated lactogenic activity on islets during late pregnancy.

Adolescent witnesses to a peer suicide

OBJECTIVE

This case-control study attempts to evaluate the psychological impact of witnessing a suicide on high school students.

METHOD

Twenty-eight high school students witnessed a firearms suicide and the serious injury of another student while riding a school bus. They were assessed 2 months after the event, and their responses were compared with 28 demographically similar adolescents from another community who had not been exposed to suicide.

RESULTS

The exposed students, when compared with the controls, had higher rates of new-onset anxiety disorder and a trend for increased rates of new-onset post-traumatic stress disorder (PTSD). Within the exposed group, measures of the closeness of the relationship to both the suicide victim and the student who was injured were correlated with the severity of PTSD symptomatology. Within the exposed group, other factors that predisposed to new-onset disorder included family history of affective illness, family history of suicide attempt, and stressful life events occurring in the year before exposure.

CONCLUSIONS

In combination with the extant literature, this study demonstrates that adolescents who witness a traumatic suicidal death are at risk for the development of psychopathology, specifically, anxiety disorders and PTSD.

Bereavement or depression? The impact of the loss of a friend to suicide

OBJECTIVE

To determine whether the depressive reactions experienced by youth exposed to suicide were uncomplicated bereavement or bona fide major depression.

METHOD

In a sample of 146 friends and acquaintances of 26 adolescent suicide victims, 43 (29%) developed a depressive episode subsequent to exposure to suicide, 18 were depressed before exposure, and 85 were never depressed. The three groups were compared.

RESULTS

Those who became depressed after exposure were similar to those who were depressed before exposure. Both depressed groups differed from the nondepressed exposed group with respect to functional impairment, depressive symptom pattern and severity, convergent validity with other measures of depression, personal and family history of depression, and stressful life events. Previous depressives showed greater comorbidity with nonaffective disorders than those who became depressed after exposure. Those who became depressed after exposure compared with both the previous and nondepressive had a closer relationship with the suicide victims, showed more severe grief, and showed more intense exposure to the suicide.

CONCLUSIONS

Depressive reactions occurring after exposure to suicide appear to be bona fide major depression, occurring as a complication of bereavement. Youth exposed to suicide should be carefully screened and followed up. Should a symptomatic picture of depression and functional impairment ensue, such exposed youth should be treated accordingly for a major depressive episode.

Firearms and adolescent suicide. A community case-control study

OBJECTIVE

To assess the association between firearms in the home and adolescent suicide.

RESEARCH DESIGN

Matched, case-control.

SETTING

Population-based community sample.

SUBJECTS

Sixty-seven adolescent suicide victims and a demographically matched group of 67 living community controls.

SELECTION PROCEDURE

The series of adolescent suicide victims was consecutive, with an overall participation rate of 74% (67/91).

MEASUREMENTS AND RESULTS

The presence, type (hand-gun vs long-gun), number, and method of storage (locked vs unlocked, loaded vs unloaded) of firearms in the home were compared between the suicide victims and controls. Even after adjusting for differences in rates of psychiatric disorders between suicide victims and controls, the association between suicide and both any gun (odds ratio [OR] = 4.4, 95% confidence interval [CI] = 1.1 to 17.5) and handguns (OR = 9.4, 95% CI = 1.7 to 53.9) in the home were both highly significant. Long-guns in the home were associated with suicide only in rural areas, whereas handguns were more closely associated with suicide in urban areas. Handguns (OR = 12.9, 95% CI = 1.5 to 110.9) and loaded guns (OR = 32.3, 95% CI = 2.5 to 413.4) in the home were particularly significant risk factors for suicide in those with no apparent psychiatric disorder.

CONCLUSIONS

When pediatricians are faced with a suicidal adolescent, they should insist on the removal of firearms from the home. Pediatricians should also inform parents that the presence of firearms may be associated with adolescent suicide even in the absence of clear psychiatric illness.

Psychiatric impact of the loss of an adolescent sibling to suicide

Twenty-five adolescent siblings of 20 adolescent suicide victims were psychiatrically assessed 6 months after the suicide, and compared to 25 demographically matched controls. Siblings were much more likely to show a new-onset major depression subsequent to exposure to suicide. New-onset depression was associated with previous psychiatric disorder, family history of any psychiatric disorder, and family history of major depression. Mothers of suicide victims, compared to the mothers of controls, were also more likely to be depressed 6 months after the suicide of their child. The development of a family-based intervention for families of adolescent suicides is recommended.

Identification of T cell peptides from C gamma 2ab involved in IgG2ab T cell-induced allotypic suppression. Relationship with the MHC haplotype of the suppressor T cell-donor Igha mice

Using the algorithm of the peptidic self-model we selected, from the constant part of the IgG2ab polypeptidic heavy chain, four peptides susceptible to being recognized by the T cells of Igha mice that prevent IgG2ab expression. Among these four peptides, two were capable of enhancing in vivo this T cell activity of Igha mice almost as well as the whole IgG2ab allotype. One of these peptides, C gamma 2ab-248-263, located in the CH3 domain of IgG2ab, was effective in H-2d mice, while the other one, C gamma 2ab-103-118, located in the hinge region of IgG2ab, was efficient in H-2b mice. This demonstrates for the first time that this suppression involves the TCR of the effector cells and peptides derived from the allotype presented in the context of MHC molecules of the target cells, the presentation specificity being dependent on the MHC haplotype. The availability of these peptides will allow us to further understand the role of class I and/or class II MHC molecules in this suppression.

Identification of T cell peptides from C gamma 2ab involved in IgG2ab T cell-induced allotypic suppression. Relationship with the MHC haplotype of the suppressor T cell-donor Igha mice

Using the algorithm of the peptidic self-model we selected, from the constant part of the IgG2ab polypeptidic heavy chain, four peptides susceptible to being recognized by the T cells of Igha mice that prevent IgG2ab expression. Among these four peptides, two were capable of enhancing in vivo this T cell activity of Igha mice almost as well as the whole IgG2ab allotype. One of these peptides, C gamma 2ab-248-263, located in the CH3 domain of IgG2ab, was effective in H-2d mice, while the other one, C gamma 2ab-103-118, located in the hinge region of IgG2ab, was efficient in H-2b mice. This demonstrates for the first time that this suppression involves the TCR of the effector cells and peptides derived from the allotype presented in the context of MHC molecules of the target cells, the presentation specificity being dependent on the MHC haplotype. The availability of these peptides will allow us to further understand the role of class I and/or class II MHC molecules in this suppression.

Psychiatric risk factors for adolescent suicide: a case-control study

OBJECTIVE

The objective of this study was to determine the psychiatric risk factors for adolescent suicide.

METHOD

Sixty-seven adolescent suicide victims were compared with 67 demographically matched community controls. Psychiatric disorder was assessed in suicide victims using a psychological autopsy protocol and in controls using similar semistructured psychiatric interviews. Risk factors were quantified by use of the odds ratio (OR), that is, the relative frequency of the occurrence of a given condition in the suicides compared with the controls.

RESULTS

The most significant psychiatric risk factors associated with adolescent suicide were major depression (OR = 27.0), bipolar mixed state (OR = 9.0), substance abuse (OR = 8.5), and conduct disorder (OR = 6.0). Substance abuse was a more significant risk factor when comorbid with affective illness than when alone (OR = 17.0 versus 3.3). The majority of depressed suicide victims had a primary affective disorder (82%). A significant minority (31%) of depressed suicide victims had been depressed less than 3 months. Previous suicide attempts, suicidal ideation, and homicidal ideation also were associated with adolescent suicide.

CONCLUSIONS

The development of effective treatments for youth who fit the above-noted risk profiles should be given high priority.

Psychiatric sequelae to the loss of an adolescent peer to suicide

OBJECTIVE

This study was designed to learn whether friends and acquaintances of suicide victims were at increased risk for depression, post-traumatic stress disorder, and suicidal behavior after exposure to suicide.

METHOD

The social networks of 26 adolescent suicide victims, consisting of 146 adolescents, were interviewed 7 months after the death of the suicide victim and compared with 146 matched, unexposed controls.

RESULTS

The rates of these disorders that had onset after exposure were elevated in the exposed group vs. controls: major depression, post-traumatic stress disorder, suicidal ideation with a plan or an attempt, but not suicidal attempts. Almost all of those exposed youth who developed new-onset suicidality did so in the context of a new-onset depressive episode. The majority of these new-onset depressive disorders began within 1 month of exposure.

CONCLUSION

Postvention programs not only should focus on the prevention of imitation of suicidal behavior, but also should provide longer term follow-up for potentially bereaved and depressed youth exposed to suicide.

RNA virus-like particles in pathogenic plant trypanosomatids

A double-stranded RNA (ds RNA) with an approximate size of 4.7 kb was found in 6 Phytomonas isolates specifically associated with plant pathogenicity in coconut trees ("Hartrot" disease) and oil palm ("Marchitez sorpressiva" disease). This ds RNA was not detected in 10 non-pathogenic Phytomonas isolates from different lactiferous plants or in the insect trypanosomatids Crithidia and Herpetomonas. Analysis by electron microscopy of a sucrose gradient fraction containing this ds RNA revealed virus-like particles.

The validity of diagnoses obtained through the psychological autopsy procedure in adolescent suicide victims: use of family history

A test of validity of the psychiatric diagnoses obtained by the psychological autopsy procedure is described in a consecutive series of 67 adolescent suicide victims. Family history of mental illness in first-degree relatives of subjects was obtained blind to subject diagnosis using the family history method. It was hypothesized that subjects with a given diagnosis, compared with subjects without this diagnosis, would show an increased rate of this disorder among first-degree relatives. This hypothesis was supported insofar as specific associations between subject diagnosis and familial rates of illness were demonstrated for major depression, bipolar illness, conduct and antisocial disorder and substance abuse. These results provide further support for the validity of diagnoses obtained through the psychological autopsy procedure.

Stressful life events, psychopathology, and adolescent suicide: a case control study

The relationship between stressful life events and adolescent suicide was assessed in 67 adolescent suicide victims and 67 matched community controls. In the year before death, suicide completers were more likely to have experienced: (1) interpersonal conflict with parents and with boy/girlfriends, (2) disruption of a romantic attachment, (3) legal or disciplinary problems. Legal or disciplinary problems were more commonly associated with suicide in conduct and substance abuse disordered youth. Interpersonal loss was more commonly associated with suicide in substance abuse as well. Even after controlling for psychopathology, legal and disciplinary problems in the past year were associated with an increased risk of suicide.

Inhibition of tumor growth by histoincompatible cells expressing interleukin-2

Murine tumor cells engineered to express IL-2 have been shown to be rejected by the syngeneic host, which is then protected against a subsequent tumorigenic challenge. To assess whether IL-2 has to be produced by the tumor cells themselves, or whether its local delivery would be sufficient to promote such beneficial effects, the syngeneic tumor cells were co-inoculated with allogeneic or xenogeneic cells secreting IL-2, selected after gene transfection. In several murine systems, it was observed that this is an efficient approach for controlling the growth of the syngeneic tumor. However, animals which rejected the tumor were not protected against a subsequent challenge. Several lines of evidence indicate that NK cells play a major role in tumor rejection induced by the IL-2 expressing histoincompatible vector cells. Thus, while local delivery of IL-2 in the vicinity of a tumor might not be sufficient to promote a systemic long-term specific antitumor immune response, it can control the growth of the primary syngeneic tumor. These experiments demonstrate the feasibility of using genetically engineered histoincompatible cells (which are rejected by the host's immune system) as a transient delivery system in vivo.

Psychiatric effects of exposure to suicide among the friends and acquaintances of adolescent suicide victims

The friends and acquaintances (N = 58) of 10 adolescent suicide victims were interviewed 6 months after the death of the victims, and the rates of psychiatric disorders that had onset after the death were compared with the 6-month incidence of psychopathology in 58 demographically and psychiatrically matched unexposed controls. The exposed group showed higher rates of any new onset major depressive disorder, but the rate of incident suicide attempts was the same in both groups. The median onset of incident depression among the exposed group was within the first month after exposure, and the majority of those exposed youth with incident depression were still depressed at interview 6 months after the death. Adolescent friends and acquaintances of suicide victims experience considerable psychiatric morbidity subsequent to exposure to suicide, most consistent with pathological grief.

Antigenic variation in Trypanosoma equiperdum

Trypanosoma equiperdum is an African trypanosome that causes dourine in horses. Like the other African trypanosomes, T. equiperdum escapes elimination by the immune system of its host by using an elaborate system of antigenic variant. The trypanosomes are covered by a coat consisting of a single protein called the variable surface glycoprotein (VSG) that acts as the major trypanosome immunogen. As the host responds to one VSG, trypanosomes covered with another VSG become dominant. There is a loose order of appearance of these VSG during the infection. The factors that affect the timing of VSG expression and the effective size of the VSG repertoire in T. equiperdum are reviewed. The VSG genes are generally activated by a process of duplicative transposition involving the duplication of a silent VSG gene and inserting a copy of the gene into an expression site. The order of VSG expression is related to the amount of homology between the silent gene and the expression site. The genes expressed late in infection lack extensive homology with the expression site and depend on homology with the gene in the expression site. The genes coding for VSG expressed late in infection are hybrid genes because of this mode of transfer. This transfer mechanism allows the trypanosome to create complex VSG genes from parts of several different silent genes that are each pseudogenes. Additionally, data are presented showing that only a limited portion of the VSG is actually seen by the host immune system. These factors indicate that the effective VSG repertoire is greater than the number of VSG genes in the trypanosome genome.

Some genetic aspects of idiopathic and symptomatic absence seizures: waking and sleep EEGs in siblings

Epileptic activity was recorded in the waking and sleep EEG of 62.5% of 80 siblings of 38 patients with absence seizures. Epileptic discharges were noted in waking only in 8.7%, in waking as well as sleep in 28.8%, and in sleep only in 25%. Generalized, partly irregular, and slow spike-wave complexes were found, twice with lateral emphasis. Spike-wave complexes were recorded in 72% of 50 siblings of patients with idiopathic absence and in 46.7% of 30 siblings of patients with symptomatic absence. One epileptic discharge was observed every 108.6 s on the average, without striking differences between siblings of patients with idiopathic (99.7 s) and symptomatic absence (119.3 s). Without any differences between siblings of children with idiopathic and symptomatic absence, the most epileptic discharges were activated in sleep stages C and D, followed by stages A and B. The highest activation rate was observed in the 7-14-year-old group (73.5%) and to a somewhat lesser degree in the group between 15 and 20 years of age (66.7%); fewer epileptic discharges were recorded in younger (25%) and older patients (28.6%). The higher activation rates in the male sex were significant only in siblings of patients with idiopathic absence. Although only five patients (13.2%) were photosensitive, a photosensitivity was found in 24% of siblings of children with idiopathic absence and in 20% of siblings of patients with symptomatic absence. Three siblings of patients with idiopathic absence also had absence seizures; in one of them a febrile seizure occurred at an earlier age. All of them showed generalized spike wave discharges in waking as well as sleep. Occipital theta delta activity with generalization was observed more frequently in siblings of patients with idiopathic absence (82.2%) than in those of patients with symptomatic absence (63.6%). Our waking and sleep EEG recordings prove that concerning etiology-genetic factors play a striking role in idiopathic absence, but are also of considerable significance in the symptomatic types.

A novel approach to the induction of specific cytolytic T cells in vivo

The induction of specific cytotoxic T lymphocytes (CTL) is one component in the immune response which can effectively protect the host against the progression of many viral infections. CTL are also known to play an important role in immune defence against tumour growth. CTL induction is dependent the presence of the specific antigen, appropriately presented, and interleukin-2 (IL2), provided by T helper lymphocytes. We studied the specific CTL response induced by tumour cells transfected with murine IL2. Our results show that tumour cells manipulated to secrete IL2 induce an improved specific anti-tumour response which results in tumour rejection in mice. To further investigate the effect of IL2 on the CTL response to different antigens, we introduced synthetic peptides into IL2-secreting tumour cells and determined the specific CTL induction in syngeneic mice immunized with these cells. We report here that such IL2-secreting cells can effectively prime peptide-specific CTL in vivo. Our data are relevant to immunotherapy and vaccine development and open up the possibility that autologous cells, manipulated to secrete IL2 and located with one or a cocktail of peptides, could be used to stimulate a specific CTL response.

Thymic carcinoma. Report of five cases and review of the literature

Among 54 mediastinal tumours we examined in the past 20 years, there were 5 cases of primary thymic carcinomas, each with widespread metastases. Histological features in three cases were consistent with lymphoepithelioma-like carcinoma. One case showed an epidermoid pattern with keratotic pearls resembling Hassall bodies. One undifferentiated carcinoma developed from a cortical thymoma. Epstein-Barr virus could not be detected in tumour tissue with in situ hybridization. A review of the literature revealed only 94 well-documented cases of thymic carcinoma. Both thymic carcinomas and thymomas are neoplasms of the thymic epithelial cells, but thymic carcinomas are obviously histologically malignant and usually not associated with any parathymic syndromes. Epidermoid and lymphoepithelioma-like carcinomas are described along with special forms, such as small- and clear-cell carcinomas, basaloid, sarcomatoid, mucoepidermoid, and adenocystic carcinoma. Compared to the other forms, lymphoepithelioma-like carcinoma has a poor prognosis in regard to metastases and rate of survival. Some thymic carcinomas may develop from pre-existing thymomas.

IL-4, but not IL-5, can act synergistically with B cell activating factor (BCAF) to induce proliferation of resting B cells

B cell activating factor (BCAF) was initially identified in the supernatant of the murine T helper cell clone 52-3 (52-3 SN) because of its ability to promote activation and proliferation of resting B cells in the absence of any other costimulus. In this paper, we show that 52-3 T helper cells also secrete IL-4 and IL-5 and we have analyzed the influence of these two lymphokines on B cell proliferation induced by BCAF-containing 52-3 SN. Using the neutralizing anti-IL-4 monoclonal antibody 11B11, we observed partial inhibition of B cell proliferation. 52-3 SN free of IL-4 prepared using an immunoabsorbent column was still able to induce significant B cell proliferation. Although recombinant IL-4 alone does not induce B cell proliferation, it increased the proliferation induced by IL-4-free 52-3 SN. Kinetic studies showed that IL-4 is required at the start of B cell cultures in order to exert optimal synergistic effects. In contrast, anti-IL-5 monoclonal antibody NC17 did not affect the B cell proliferative activity of 52-3 SN whether or not IL-4 was present. When 52-3 SN was tested on dextran-sulfate-activated B cells, IL-5 and BCAF activities were detected but only the IL-5 activity was neutralized by monoclonal antibody NC17. These results demonstrate that (i) BCAF-containing SN can induce proliferation of resting B cells independently of IL-4 and IL-5, and (ii) IL-4, but not IL-5, can act synergistically with BCAF to induce B cell proliferation.

Allogeneic manipulation of the GAT idiotypic cascade. Immunization of C57BL/6 mice by BALB/c anti-idiotypes stimulates similar strain-specific V genes as the original antigen

Antibodies specific for the immunizing Ag (Ab1) (Id+ Ag+) and Ab3 (Id+ Ag+ or Id+ Ag-) of the (Glu60 Tyr10 Ala30) (GAT) idiotypic cascade express similar pGAT public determinants in BALB/c and C57BL/6 strains. These determinants have been shown to be dependent upon both VH and Vkappa encoded segments. The VH of the BALB/c Ab1 (germ-line gene H10) and that of the C57BL/6 Ab1 (germ-line gene V186-2) are only 75% homologous, whereas VK are much more conserved. C57BL/6 mice were immunized with BALB/c Ab2 (anti-idiotypic) antibodies and monoclonal Ab3 were derived after fusion of immunized spleen cells with the nonsecreting hybridoma cell line Sp/2.0-Ag. From 13 cell lines, five clones (four Id+ Ag- and one Id+ Ag+) were isolated and the mRNA V regions sequenced. Immunization with BALB/c anti-idiotypes elicits expression of the same or closely related C57BL/6 VH and Vkappa genes as when C57BL/6 mice were immunized with GAT, although functional VH BALB/c equivalents have been isolated in the B6 strain. Our results suggest that manipulation of the repertoire via antigenic or idiotypic stimulation both lead to the expression of different genes in different strains. They further confirm that the immune system is largely degenerate, for both idiotype expression and Ag recognition.

Allogeneic manipulation of the GAT idiotypic cascade. Immunization of C57BL/6 mice by BALB/c anti-idiotypes stimulates similar strain-specific V genes as the original antigen

Antibodies specific for the immunizing Ag (Ab1) (Id+ Ag+) and Ab3 (Id+ Ag+ or Id+ Ag-) of the (Glu60 Tyr10 Ala30) (GAT) idiotypic cascade express similar pGAT public determinants in BALB/c and C57BL/6 strains. These determinants have been shown to be dependent upon both VH and Vkappa encoded segments. The VH of the BALB/c Ab1 (germ-line gene H10) and that of the C57BL/6 Ab1 (germ-line gene V186-2) are only 75% homologous, whereas VK are much more conserved. C57BL/6 mice were immunized with BALB/c Ab2 (anti-idiotypic) antibodies and monoclonal Ab3 were derived after fusion of immunized spleen cells with the nonsecreting hybridoma cell line Sp/2.0-Ag. From 13 cell lines, five clones (four Id+ Ag- and one Id+ Ag+) were isolated and the mRNA V regions sequenced. Immunization with BALB/c anti-idiotypes elicits expression of the same or closely related C57BL/6 VH and Vkappa genes as when C57BL/6 mice were immunized with GAT, although functional VH BALB/c equivalents have been isolated in the B6 strain. Our results suggest that manipulation of the repertoire via antigenic or idiotypic stimulation both lead to the expression of different genes in different strains. They further confirm that the immune system is largely degenerate, for both idiotype expression and Ag recognition.

Biochemical characterization and biological effects of partially purified B cell-activating factor (BCAF)

B cell-activating factor (BCAF) has been characterized and partially purified from the supernatant of the murine tumor T cell line 373. BCAF has an apparent molecular mass of 15 to 20 kDa when analyzed by Superose 12 fast protein liquid chromatography (FPLC) gel filtration and a pI of 4.5 to 5.0 when analyzed by FPLC chromatofocusing. Concentrated supernatant was applied to a nickel chelating column and unadsorbed active material was further purified by two sequential C4 reverse-phase high-performance liquid chromatography steps. This purification procedure allowed a complete separation of interleukin 2 and interleukin 4 activities from BCAF. This partially purified BCAF induces Ia expression, cell size increase and proliferation of small resting B cells. Furthermore, we have shown that the activity of partially purified BCAF is insensitive to treatment by monoclonal antibodies specific for interleukin 4 and interleukin 5.

Antigenic variation in parasitic protozoa

Antigenic variation in the protozoan parasites responsible for malaria and African sleeping sickness is examined. Some of the molecular mechanisms responsible for the generation of new variant antigens are reviewed and the possible problems posed by this process in the development of vaccines against these parasites are discussed.

Bone block transfer of coracoacromial ligament in acromioclavicular injury

A bone block transfer of coracoacromial ligament into the medullary canal of the clavicle for Grade III acromioclavicular injury was developed in an attempt to prevent occasional pullout of the ligament in the procedure described by Weaver and Dunn. Fifteen consecutive cases (12 acute, three chronic) with Grade III acromioclavicular injury were treated by this method. All but one patient regained painless full range of shoulder motion. All patients returned to previous activity. Failure of coracoclavicular reconstruction occurred in one case. Asymptomatic focal myositis ossificans developed in four cases with no functional deficit.

Stable expression of two variable surface glycoproteins by cloned Trypanosoma equiperdum

African trypanosomes are thought to evade the host immune system by periodically changing their variable surface glycoprotein (VSG). VSG genes are activated by a complex process involving the duplicative transposition of silent basic copy genes to one of several expression sites. These expression-linked copies (ELCs) of the VSG genes are also subject to regulation within expression sites by as yet unknown mechanisms. It is generally assumed that trypanosomes can express only one VSG gene at a time. Nevertheless, the finding that they contain multiple VSG gene expression sites suggests that multiple expression is possible. We show here that Trypanosoma equiperdum can stably express two VSG genes in a simple axenic culture system and that both antigens are present on the cell surface. The two antigens do not co-cap or form heterodimers. Their corresponding genes show no cross-hybridization and are situated in different telomere-linked expression sites. Northern blot analysis reveals that both genes are active in the double expressors.

Gene repertoire of the anti-poly(Glu60Ala30Tyr10) (GAT) immune response: comparison of VH, V kappa, and D regions used by anti-GAT antibodies and monoclonal antibodies produced after anti-idiotypic immunization

Eight monoclonal antibodies were selected from BALB/c mice immunized with two different monoclonal anti-idiotypic antibodies recognizing two discrete idiotopes characteristic of the anti-poly(Glu60Ala30Tyr10) (GAT) antibody response. These monoclonal antibodies were previously classified as Ab1 (anti-GAT-like) and Ab3 (anti-anti-idiotype) on the basis of expression of the public idiotypic specificity (p.GAT) studied with a xenogeneic serum, anti-GAT activity, and expression of various public idiotopes. All the heavy chain variable region (VH) sequences from Ab1 are nearly identical to the VH sequences of Ab1 anti-GAT monoclonal antibodies. The same type of results has been found with the Ab1 kappa light chain variable region (V kappa) sequences. Confirming our classification, Ab3 VH and V kappa sequences were found to be completely different from Ab1 VH and V kappa sequences. The Ab1 diversity (D) regions are different from one another and different from the D regions found on monoclonal anti-GAT antibodies but function similarly. These D regions are not simply derived from already described D genes. Finally, our results suggest that in the anti-GAT response VH and V kappa sequence are mainly responsible for idiotype expression.

Immune response against poly(Glu60,Ala30,Tyr10) (GAT): immunization with monoclonal anti-idiotypic antibodies leads to the predominant stimulation of idiotypically similar immunoglobulins with anti-GAT activity

Two monoclonal anti-idiotypic antibodies (HP-Id20 and HP-Id22) recognizing two different public idiotopes expressed in the anti-poly(Glu60,Ala30,Tyr10) (GAT) response were used to immunize BALB/c and C57BL/6 mice. From these animals hybridomas were isolated. From BALB/c and C57BL/6 mice eight and seven monoclonal antibodies were characterized, respectively. The reagents were classified according to the expression of the public idiotypic specificity p.GAT (recognized by a rabbit antiserum). The anti-GAT activity and the expression of the various idiotopes characterized on anti-GAT polyclonal and monoclonal antibodies were also studied. Most of the reagents are Ab1'-type of antibody resembling anti-GAT antibodies. One anti-anti-idiotypic monoclonal antibody (Ab3) was also isolated from BALB/c mice. This suggests that in this experimental model the repertoire induced after HP-Id immunization and antigen stimulation is comparable. The idiotypic analysis of a large number of anti-GAT and of Ab1' monoclonal antibodies suggests that only two public idiotopes are involved in the anti-GAT response.