Ribosomal quality control factors inhibit repeat-associated non-AUG translation from GC-rich repeats

A GGGGCC (G4C2) hexanucleotide repeat expansion in C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD), while a CGG trinucleotide repeat expansion in FMR1 leads to the neurodegenerative disorder Fragile X-associated tremor/ataxia syndrome (FXTAS). These GC-rich repeats form RNA secondary structures that support repeat-associated non-AUG (RAN) translation of toxic proteins that contribute to disease pathogenesis. Here we assessed whether these same repeats might trigger stalling and interfere with translational elongation. We find that depletion of ribosome-associated quality control (RQC) factors NEMF, LTN1 and ANKZF1 markedly boost RAN translation product accumulation from both G4C2 and CGG repeats while overexpression of these factors reduces RAN production in both reporter assays and C9ALS/FTD patient iPSC-derived neurons. We also detected partially made products from both G4C2 and CGG repeats whose abundance increased with RQC factor depletion. Repeat RNA sequence, rather than amino acid content, is central to the impact of RQC factor depletion on RAN translation-suggesting a role for RNA secondary structure in these processes. Together, these findings suggest that ribosomal stalling and RQC pathway activation during RAN translation inhibits the generation of toxic RAN products. We propose augmenting RQC activity as a therapeutic strategy in GC-rich repeat expansion disorders.

Ribosomal quality control factors inhibit repeat-associated non-AUG translation from GC-rich repeats

A GGGGCC (G4C2) hexanucleotide repeat expansion in C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD), while a CGG trinucleotide repeat expansion in FMR1 leads to the neurodegenerative disorder Fragile X-associated tremor/ataxia syndrome (FXTAS). These GC-rich repeats form RNA secondary structures that support repeat-associated non-AUG (RAN) translation of toxic proteins that contribute to disease pathogenesis. Here we assessed whether these same repeats might trigger stalling and interfere with translational elongation. We find that depletion of ribosome-associated quality control (RQC) factors NEMF, LTN1, and ANKZF1 markedly boost RAN translation product accumulation from both G4C2 and CGG repeats while overexpression of these factors reduces RAN production in both reporter cell lines and C9ALS/FTD patient iPSC-derived neurons. We also detected partially made products from both G4C2 and CGG repeats whose abundance increased with RQC factor depletion. Repeat RNA sequence, rather than amino acid content, is central to the impact of RQC factor depletion on RAN translation - suggesting a role for RNA secondary structure in these processes. Together, these findings suggest that ribosomal stalling and RQC pathway activation during RAN translation elongation inhibits the generation of toxic RAN products. We propose augmenting RQC activity as a therapeutic strategy in GC-rich repeat expansion disorders.

Antimicrobial agent triclosan disrupts mitochondrial structure, revealed by super-resolution microscopy, and inhibits mast cell signaling via calcium modulation

The antimicrobial agent triclosan (TCS) is used in products such as toothpaste and surgical soaps and is readily absorbed into oral mucosa and human skin. These and many other tissues contain mast cells, which are involved in numerous physiologies and diseases. Mast cells release chemical mediators through a process termed degranulation, which is inhibited by TCS. Investigation into the underlying mechanisms led to the finding that TCS is a mitochondrial uncoupler at non-cytotoxic, low-micromolar doses in several cell types and live zebrafish. Our aim was to determine the mechanisms underlying TCS disruption of mitochondrial function and of mast cell signaling. We combined super-resolution (fluorescence photoactivation localization) microscopy and multiple fluorescence-based assays to detail triclosan's effects in living mast cells, fibroblasts, and primary human keratinocytes. TCS disrupts mitochondrial nanostructure, causing mitochondria to undergo fission and to form a toroidal, "donut" shape. TCS increases reactive oxygen species production, decreases mitochondrial membrane potential, and disrupts ER and mitochondrial Ca²⁺ levels, processes that cause mitochondrial fission. TCS is 60 × more potent than the banned uncoupler 2,4-dinitrophenol. TCS inhibits mast cell degranulation by decreasing mitochondrial membrane potential, disrupting microtubule polymerization, and inhibiting mitochondrial translocation, which reduces Ca²⁺ influx into the cell. Our findings provide mechanisms for both triclosan's inhibition of mast cell signaling and its universal disruption of mitochondria. These mechanisms provide partial explanations for triclosan's adverse effects on human reproduction, immunology, and development. This study is the first to utilize super-resolution microscopy in the field of toxicology.

2-Azetidinone cholesterol absorption inhibitors: increased potency by substitution of the C-4 phenyl ring

SAR studies directed towards the optimization of 2-azetidinone cholesterol absorption inhibitors led to the discovery of 11a, the most potent cholesterol absorption inhibitor yet identified.

Carboxy-substituted 2-azetidinones as cholesterol absorption inhibitors

Metabolism initiated SAR studies led to the discovery of a new class of potent 2-azetidinone cholesterol absorption inhibitors. These studies found that a heteroatom at the para position of the C-4 phenyl ring is not a requirement for cholesterol absorption inhibition as was suggested by earlier findings. Substitution of Ph-linker-COOR for PhOMe at the C-4 position enhanced cholesterol absorption inhibition.

Sugar-substituted 2-azetidinones as cholesterol absorption inhibitors

The asymmetric synthesis of a glucuronide conjugate of the 2-azetidinone cholesterol absorption inhibitor Sch 48461 was accomplished to confirm the structure of a metabolite isolated from in vivo sources. Key features of this article include the asymmetric synthesis of 2-azetidinones by Evan's chiral oxazolidinone methodology and glucuronide formation by a Mitsunobu protocol.

2-Azetidinone cholesterol absorption inhibitors: structure-activity relationships on the heterocyclic nucleus

A series of azetidinone cholesterol absorption inhibitors related to SCH 48461 ((-)-6) has been prepared, and compounds were evaluated for their ability to inhibit hepatic cholesteryl ester formation in a cholesterol-fed hamster model. Although originally designed as acyl CoA: cholesterol acyltransferase (ACAT) inhibitors, comparison of in vivo potency with in vitro activity in a microsomal ACAT assay indicates no correlation between activity in these two models. The molecular mechanism by which these compounds inhibit cholesterol absorption is unknown. Despite this limitation, examination of the in vivo activity of a range of compounds has revealed clear structure-activity relationships consistent with a well-defined molecular target. The details of these structure-activity relationships and their implications on the nature of the putative pharmacophore are discussed.

Inhibitors of acyl CoA:cholesterol acyltransferase

Conformational restriction of previously disclosed acyclic (diphenylethyl)diphenylacetamides led to the discovery of several potent inhibitors of acyl CoA:cholesterol acyltransferase (ACAT). cis-[2-(4-Hydroxyphenyl)-1-indanyl]diphenylacetamide (4a) was the most potent ACAT inhibitor identified (IC50 = 0.04 microM in an in vitro rat hepatic microsomal ACAT assay, ED50 = 0.72 mg/kg/day in cholesterol-fed hamster.

Computed tomography detection of active mesenteric hemorrhage following blunt abdominal trauma

Following blunt abdominal trauma, patients still may be actively bleed ing, despite seeming hemodynamically stable. By detecting extravasation of contrast-enhanced blood in the absence of any other evidence to support solid visceral injury as the source, computed tomography (CT) scanning was able to indicate ongoing hemorrhage in two patients, thought most likely of mesenteric origin. This information influenced the decision for intervention, which in these two cases was laparotomy, where bleeding torn mesenteric vessels were confirmed.

The role of women in the AIDS epidemic

Two aspects of the role of women in the AIDS epidemic are discussed. Firstly, the role of women in the epidemic and secondly how does HIV/AIDS affect women. Currently it is estimated that over four million women are infected with HIV and more attention is increasingly being paid to this group. Women have been functionally socialized in a dual role, namely that of care giver and service provider. The generally low status of women in the developing world needs to be corrected by empowering women to deal with the epidemic through education and equal social and sexual status to men. Epidemiological data concerning women and HIV/AIDS are presented and the possible effect of HIV/AIDS on women is discussed. Candidiasis, pelvic inflammatory diseases and cervical neoplastic lesions require further attention. Finally, a number of recommendations, including human rights, are presented to enable women worldwide successfully to cope with the HIV epidemic.

Prevalence of hepatitis C in South Africa: detection of anti-HCV in recent and stored serum

The prevalence of anti-HCV was studied in a cohort of 2,072 South Africans. The results were compared in selected recently collected sera and in stored sera. The serum ALT and anti-HBc were also studied as surrogate markers in this population. The following groups were tested: (a) 498 urban, black blood donors (b) 500 white blood donors (c) 500 Asian blood donors (d) 216 rural hospitalized patients (e) 358 rural mineworkers. Sera found positive by the original ELISA were retested, and reproducibly positive tests in rural black men (group d) were confirmed both by recombinant immunoblot assay and by a second ELISA. An anti-HCV prevalence of 1.2%, 0.8%, and 0.6% in urban blacks, Asians, and whites was found. Antibodies to hepatitis B core antigen were found in 42.9%, 3.4%, and 1.2% of black, Asian, and white donors, respectively; 76% of donors positive for anti-HCV were anti-HBc negative. In rural African men, 17% of stored serum samples and 9.2% of recently collected serum samples were positive for anti-HCV. In this cohort 3.84% were positive by all three assays. These results suggest that the prevalence of anti-HCV in low and high-risk South African urban blood donors is comparable to high and low prevalence areas in Europe, the United States, and Japan, but indicates a relatively high degree of exposure to hepatitis C in rural African men. The reactivity of stored, frozen sera in this population requires further investigation. In South African urban blood donors, surrogate marker testing will not expedite HCV screening.

Transfusion-related human immunodeficiency virus in patients with haemophilia in Johannesburg

Tests were carried out on 198 patients with inherited coagulation disorders attending haemophilia clinics of Johannesburg and Baragwanath Hospitals for the prevalence of antibodies to the human immunodeficiency virus (HIV). This cohort of patients has been treated with locally produced (South African) blood products from volunteer donors, except for a 15-month period in 1982-1984 when, owing to a shortage of locally produced material, an imported large donor-pool US factor VIII concentrate was used. Not all patients received this material. Of the haemophilia A patients who received the imported factor VIII concentrate, 85% were seropositive, while only 3% of the patients who received locally produced small donor-pool products were seropositive. No factor VIII-deficient patients have seroconverted while using small donor-pool products, since the introduction of routine screening of blood donations and strict exclusion criteria of donors. However, despite testing of blood products, 3 patients receiving locally produced factor IX concentrate (4,000 donors) seroconverted in 1988, having previously been HIV-negative. Factors influencing the choice of blood products to be used, especially in South Africa, are discussed.

Dietary iron overload in southern African rural blacks

A survey conducted in rural southern African black subjects indicated that dietary iron overload remains a major health problem. A full blood count, erythrocyte sedimentation rate, serum concentrations of iron, total iron-binding capacity, ferritin, C-reactive protein (CRP), gamma-glutamyltransferase (GGT) and serological screening for hepatitis B and human immunodeficiency virus (HIV) infections were carried out in 370 subjects (214 inpatients and 156 ambulatory Mozambican refugees). The fact that the geometric mean (SD range) serum ferritin concentration was much higher in the male hospital patients than in subjects living in the community [1,581 micrograms/l (421-5,944 micrograms/l) and 448 micrograms/l (103-1,945 micrograms/l) respectively] suggested that dietary iron overload was not the only factor raising the serum ferritin concentration. The major additional factor appeared to be inflammation, since the geometric mean (SD range) serum CRP was significantly higher in male hospital patients [21 mg/l (8-53 mg/l)] than in subjects in the community [3 mg/l (1-5 mg)]. Alcohol ingestion, as judged by history and by serum GGT concentrations, was also associated with significantly raised serum ferritin concentrations. This finding was ascribed to the fact that traditional brews are not only associated with alcohol-induced hepatic damage but are also a very rich source of highly bio-available iron. The role of iron overload in the genesis of the raised serum ferritin concentrations are confirmed in the diagnostic liver biopsy study. The majority of biopsies showed heavy siderosis, with varying degrees of hepatic damage.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV infection in South Africa, 1982-1988--a review

A review of human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS) in South Africa between 1982 -1988 is presented. One hundred and sixty-six cases of AIDS have been seen in South Africa so far, with a mortality rate of 59.2%. There has been a predicted and alarming increase in the number of cases of AIDS in the black population. A total of 1857 HIV antibody-positive sera have been tested by various laboratories in the RSA, but this figure excludes sera found to be positive in the mining industry. The HIV-positive and AIDS cases include members of all population groups. A number of surveillance studies are presented. These revealed that beyond the groups at high risk for HIV infection the prevalence of this infection is still very low. Of an estimated 710,000 blood donors tested, 244 were positive for HIV-1 antibodies. Although 1 case of HIV-2 infection was detected in South Africa, this does not constitute a problem at present. No evidence of infection with HIV-1 was detected in southern and central African sera taken between 1970 and 1974. In the absence of a vaccine and specific treatment a change of sexual behavior to one of safer sex practices through education is the only means we have of containing the spread of the epidemic.

Evaluation of the effectiveness of AIDS training and information courses

Acquired immunodeficiency syndrome (AIDS) is considered to be the major health threat of the 20th century. The only way to contain the spread of AIDS is by prevention of infection in the first place. This task is essentially one of education. Because the South African Institute for Medical Research is traditionally associated with the prevention of infectious diseases, an AIDS Centre was established to promote education. As part of the launching of the Centre in January 1988, a series of four 1-day courses was held for different target groups. Attendance rates were high and all participants completed a pre- and post-test questionnaire designed to evaluate the effectiveness of the courses and identify existing level of knowledge, present needs and possible future demands. Collected data were examined by correlation analysis, the chi-square test and the t-test. Results generally showed improved changes in knowledge and attitudes about AIDS, and pointed the way forward for future education interventions in the community.

Photosensitivity and anti-Ro (SS-A) antibodies in black patients with systemic lupus erythematosus (SLE)

Ninety-two patients with SLE, 36 black and 56 white, were studied prospectively for photosensitivity and anti-Ro (SS-A) and anti-La (SS-B) antibodies. Photosensitivity was found in 19% of black patients, compared to 71% of white patients (p = 0.001). Anti-Ro antibodies were found in 69% of black and 54% of white patients (p = 0.013). Photosensitivity was present in 87% of Ro-positive white patients and in 54% of Ro-negative white patients (p = 0.007). However, in black patients with SLE there was a strong negative association: 4% of Ro-positive patients were photosensitive while 55% of Ro-negatives were photosensitive (p = 0.001). This suggests that black SLE patients may possess a factor which 'blocks' photosensitivity, perhaps by preventing local tissue damage caused by the interaction of Ro antibodies and ultraviolet light.

Differences in the regional prevalence of chronic hepatitis B in southern Africa--implications for vaccination

Chronic hepatitis B infection is an important cause of cirrhosis and subsequent hepatocellular carcinoma in South Africa. The disease can now be prevented by vaccination, but second-generation genetically engineered vaccines still necessitate planned allotment. We have tested 29,312 black southern African mineworkers for hepatitis B surface antigen (HBsAg) to indirectly ascertain the relative prevalence of hepatitis B infection in diverse linguistic and ethnic groups. The overall prevalence of HBsAg in this cohort of predominantly rural men was 9.9%, but the prevalence in men from different regions varied from 5.5% to 14%. The relative prevalence in 200 magisterial districts was ranked; these percentage prevalences ranged from 0% to 17%. A significantly lower mean prevalence was detected in Southern Sotho subjects than in those from coastal districts (Nguni). Based on these data, we believe that there are perhaps 2 million hepatitis B carriers in South Africa. The collected data in this report could provide a basis for a broad-based vaccine campaign whereby hepatitis B vaccine could be targeted to high-priority districts initially. This strategy could rapidly reduce the critical mass of carriers, and hasten control of the disease.

Regional prevalence of hepatitis B, delta, and human immunodeficiency virus infection in southern Africa: a large population survey

Although hepatitis B infection is endemic in southern Africa, a changing epidemiology of the disease has recently been documented in the region. The authors surveyed migrant southern African male mineworkers during 1986 to establish the prevalence of chronic hepatitis B and D (delta) infection in their areas of origin. Hepatitis B surface antigen (HBsAg) was tested in 29,312 adult male mineworkers from 18 geographic regions, encompassing the diverse tribal and linguistic groups in the region, as well as in expatriate mineworkers from neighboring southern African countries. The same cohort was also tested for antibody to human immunodeficiency virus (HIV). Selected hepatitis B carriers were also tested for hepatitis B virus deoxyribonucleic acid (DNA), antibody to hepatitis D (anti-HD), and alpha-fetoprotein. The overall prevalence of HBsAg in this survey was 9.9%. However, the prevalence varied from 5.5% to 14% in different ethnic groups. A minority of carriers (4.9%) had replicative hepatitis B infection and were hepatitis B virus DNA-positive. Only 0.6% of tested carriers were anti-HD-positive. Alpha-fetoprotein determinations were abnormal in 1.2% of hepatitis B-positive men. These data show that although chronic hepatitis B infection remains widespread in southern Africa, carrier rates vary significantly from region to region. In contrast, hepatitis D co-infection remains extremely uncommon. These baseline seroprevalence data also establish that HIV infection was, in 1986, a rare infection in the indigenous population of South Africa.

Kaposi's sarcoma in different populations in South Africa

Patients with Kaposi's sarcoma (13 black and 5 white heterosexuals and 2 homosexuals with the acquired immunodeficiency syndrome (AIDS)) were investigated clinically, histologically, serologically and immunologically. Clinically, lymph node involvement was present in 9 of the 13 black heterosexuals, but was not seen in the other two groups. Oedema, which was seen in 13 of the 14 black patients, was only present in 1 white patient. The lesions were of the nodular cutaneous type except in the AIDS patients who presented with plaque-like lesions. Whereas all non-AIDS patients were negative for HTLV-III antibodies, both AIDS patients were positive and showed a marked cell-mediated immune (CMI) deficiency. Only 1 heterosexual white and 4 heterosexual black patients had some degree of CMI deficiency. South Africans with Kaposi's sarcoma do not have significant underlying immunodeficiency or associated opportunistic infections. No serological or electron microscopic evidence was found to support the aetiological role of cytomegalovirus in Kaposi's sarcoma. The findings suggest that the cell of origin of this tumour is the vascular endothelial cell.

AIDS and related conditions--infection control. Guidelines for health care workers involved in patient management and investigation

The aetiology, transmission, clinical spectrum, complicating opportunistic infections and neoplasias (such as Kaposi's sarcoma) and the diagnosis of acquired immune deficiency syndrome (AIDS) are described. Precautions to be observed by health care workers with regard to the handling of patients with AIDS and AIDS-related conditions are detailed, as are instructions relating to the handling of blood, secretions, excretions and tissues for laboratory and health care workers. These include the use of protective clothing and sterilization of instruments, and the correct disposal of infected fomites, needles, syringes and other disposable hardware. The need for counselling patients infected with the AIDS virus is stressed.

Sero-epidemiology of HTLV-III antibody in southern Africa

A preliminary survey has demonstrated that antibodies directed against human T-cell leukaemia virus type III (HTLV-III), the virus implicated as the agent causing the acquired immunodeficiency syndrome, are not present in the low-risk population groups studied. The survey, in which an indirect immunofluorescence assay was used, has indicated that HTLV-III is not endemic in southern Africa (as opposed to central Africa, where it has been suggested that the virus is endemic). Anti-HTLV-III antibodies were, however, found in sera from male homosexuals, the one high-risk population group studied.

Eosinophilia in premature neonates. Phase 2 of a biphasic granulopoietic response

Eosinophilia within the first 6 weeks of life was studied prospectively in 10 premature neonates. Mean birthweight was 1229 +/- 314 g, and mean gestational age 31.5 +/- 1.8 weeks. Simultaneous changes in eosinophil, neutrophil, total lymphocyte, suppressor and helper T-cell counts and IgE levels were monitored. Infants were designated as responders (eosinophils greater than 1000/microliter for greater than 5 days) and non-responders. In the 6 responders eosinophils increased from 353 +/- 76 (mean +/- SEM) at birth to a peak of 2783 +/- 430/microliter at 20-25 days. Responders had significantly lower neutrophil counts at birth (P less than 0.05), and in 5 of the 6 responders neutrophils increased by more than 100% within 10-15 days; this did not occur in any of the 4 non-responders (P less than 0.025). Lymphocytes and suppressor and helper T cells increased progressively in both groups over the period of study with no differences between responders and non-responders. Birthweight and gestational age were similar in both groups, and there were no apparent causes for the lower neutrophil counts in responders at birth. Eosinophilia was not related to an IgE response. The incidence of eosinophilia in this study is similar to that reported previously, and appears to be part of a biphasic granulopoietic response.

The enhancement of eosinophil function by lymphocyte supernatants

Supernatants obtained from non-stimulated lymphocytes, lymphocytes stimulated with phytohaemagglutinin and lymphocytes from patients with schistosomiasis that were stimulated with Schistosomiasis haematobium ova were shown to enhance a number of eosinophil functions. Eosinophil chemotaxis, phagocytosis, microbicidal activity, Nitro blue tetrazolium reduction, hexose monophosphate shunt activity and glycolysis were increased. Eosinophil iodination was not affected. Only those supernatants obtained from phytohaemagglutinin stimulated lymphocytes and lymphocytes from patients with schistosomiasis that were stimulated with S. haematobium ova showed eosinophil chemotactic activity. The active factor was found to be heat stable, and had no effect on cAMP and cGMP metabolism. The most likely mechanism of enhanced eosinophil function is through the increased activity of the hexose monophosphate shunt activity and glycolysis.

Serum trace elements and vitamin A in leprosy subtypes

Serum zinc, copper, iron, and vitamin A levels were determined in patients with leprosy and healthy controls. Leprosy patients were classified according to the Ridley and Jopling classification and divided into two main groups as follows: tuberculoid, which consisted mainly of borderline tuberculoid patients and lepromatous, which consisted of borderline lepromatous and true lepromatous patients. The lepromatous group was found to have significantly lower serum levels of zinc and iron and elevated levels of copper. Vitamin A levels were also significantly lower in the lepromatous groups than in the tuberculoid group. Furthermore, the true lepromatous vitamin A determinations were significantly lower than those of the borderline lepromatous patients. The mechanism of these alterations in trace elements is probably due to a redistribution of these metals from the blood to various tissues; brought about by the release of leucocyte endogenous mediators by continuing phagocytosis of tissue macrophages in the lepromatous group of patients.

The in vivo and in vitro effects of levamisole in patients with lepromatous leprosy

Levamisole, 150 mg daily, was administered on 2 consecutive days per week for 6 weeks to two groups of patients with lepromatous leprosy. Group I was composed of patients who were receiving specific anti-leprosy therapy for varying periods of time and Group II were untreated lepromatous patients. Whereas half the patients in Group I received levamisole and the other half a placebo, those in Group II all received levamisole. Patients in both groups showed a) no clinical improvement, b) no conversion of the lepromin reaction, c) no histological change in skin biopsies, d) conversion of SKSD skin reactions from negative to positive in 20% of patients from each group, and e) unaltered absolute neutrophil counts. Whereas the total lymphocyte counts were unchanged in patients from Group I, 13 patients from Group II showed an increased lymphocyte count of greater than 10%. Lymphocyte transformation and lymphokine production in the second group showed no significant change, although four patients showed some lymphokine production after levamisole therapy. E and EAC rosettes were significantly increased in cases where these were reduced prior to treatment with levamisole-Side effects due to levamisole were not experienced.

Eosinophil degranulation. Monitoring by interference contrast microscopy

A method is described for the quantitative monitoring of human eosinophil degranulation using interference contrast microscopy. Using staphyloccoci as a stimulus, degranulated cells appeared larger than nondegranulating cells, were ameboid in shape and exhibited large nude areas of cytoplasm with prominent nuclei. Granules were observed to marginate along the plasma membrane and discharge into the exterior of the cell. Eosinophils that were not induced to degranulate were spherical in shape and the cytoplasm contained numerous granules that often obscured the nuclei. Pharmacological agents that increase intracellular cAMP prevented degranulation, whereas those that increase cGMP had no effect on degranulation. Colchicine inhibited degranulation but did not interfere with the phagocytosis of staphyloccoci. Endotoxin-activated serum, ECF-A, phytohemagglutinin, concanavalin A, levamisole, and compound 48/80 caused degranulation of eosinophils per se. The presence of disodium cromoglycate prevented this degranulation. Compound 48/80 and disodium cromoglycate had no effect on the level of intracellular cAMP and cGMP.

The effects of a soluble factor released by sensitized mononuclear cells incubated with S. haematobium ova on eosinophil migration

Incubation of sensitized mononuclear cells from patients with schistosomiasis with specific antigen containing a suspension of viable Schistosoma haematobium ova resulted in the release of a soluble factor which was chemotactic for eosinophils. Production of this substance was detectable at 24 h and demonstrated peak chemotactic activity after 2 days in culture. The chemotactic potential was dose-dependent and attracted eosinophils obtained from patients with schistosomiasis or allergic diathesis. Human neutrophil motility was unaffected by this chemoattractant. Preliminary studies demonstrated that the chemotactic factor is a heat-stable substance with peak activity associated with a molecular weight of approximately 42,000. These findings may reflect an in vitro correlate of cell-mediated immunity and may indicate a role played by the lymphocyte in the control of eosinophil function in human biology.

Production of a suppressor factor by human adherent cells treated with mycobacteria

Human peripheral blood mononuclear cell (MN) proliferation and lymphokine production induced by mitogen could be inhibited by heat killed whole mycobacteria. The inhibition was induced by a wide variety of mycobacteri but not by other Gram-positive or Gram-negative organisms or by latex particles. Proliferation and lymphokine production by adherent cell-depleted lymphocytes was not inhibited by these organisms. Adherent cells treated with mycobacteria had the ability to inhibit lymphocyte blastogenesis when co-cultured with the lymphocytes. the inhibitory effect of these adherent cells was due to the release of a heat stable, nondialyzable suppressor cells. These latter cells, which were T gamma cells, could inhibit the blastogenic ability of normal lymphocytes activated by mitogens. The results suggest that in situations of high mycobacterial load, adherent cells are activted to release a suppressor factor that will activate lymphocytes to become suppressor cells. This mechanism may explain the anergy associated with lepromatous leprosy or advanced tuberculosis.

Production of a suppressor factor by human adherent cells treated with mycobacteria

Human peripheral blood mononuclear cell (MN) proliferation and lymphokine production induced by mitogen could be inhibited by heat killed whole mycobacteria. The inhibition was induced by a wide variety of mycobacteri but not by other Gram-positive or Gram-negative organisms or by latex particles. Proliferation and lymphokine production by adherent cell-depleted lymphocytes was not inhibited by these organisms. Adherent cells treated with mycobacteria had the ability to inhibit lymphocyte blastogenesis when co-cultured with the lymphocytes. the inhibitory effect of these adherent cells was due to the release of a heat stable, nondialyzable suppressor cells. These latter cells, which were T gamma cells, could inhibit the blastogenic ability of normal lymphocytes activated by mitogens. The results suggest that in situations of high mycobacterial load, adherent cells are activted to release a suppressor factor that will activate lymphocytes to become suppressor cells. This mechanism may explain the anergy associated with lepromatous leprosy or advanced tuberculosis.

In vitro effects of histamine on eosinophil migration

Histamine at concentrations of 5 X 10(-6) to 5 X 10(-5) M increased eosinophil movement to endotoxin-activated serum (EAS). This effect was due entirely to stimulation of random migration (chemokinesis). Directional motility (true chemotaxis) was inhibited by these concentrations. Regulation of chemotaxis was apparently mediated via an H2 receptor as metiamide, an H2 receptor antagonist, but not diphenylhydramine hydrochloride, an H1 receptor antagonist, blocked the histamine-induced inhibition of chemotaxis. Both histamine and metiamide when used alone had no effect on eosinophil motility. The histamine effects on motility were associated with increased levels of intracellular cAMP, whereas cGMP levels were not affected.

Overwhelming pneumococcaemia 17 years after splenectomy. A case report

We present a case of fulminant pneumococcaemia and disseminated intravascular coagulopathy in a young adult man 17 years after splenectomy. The clinical presentation, laboratory and postmortem findings are discussed. The diagnosis, management and prophylaxis of overwhelming infections in splenectomized patients are reviewed. The advent of pneumococcal and other vaccines could contribute significantly to the successful protection of asplenic patients against certain severe infections.

Polymorphonuclear cell function in the various polar types of leprosy and erythema nodosum leprosum

Polymorphonuclear leukocyte motility, both in vivo and in vitro, and reduction of Nitro Blue Tetrazolium was studied in tuberculoid and lepromatous leprosy patients and a group of lepromatous patients with erythema nodosum leprosum (ENL). A profound defect in random migration, chemotaxis, and chemokinesis was found in lepromatous patients with and without complicating ENL, and marked depletion of skin window migration confirmed these in vitro findings. Tuberculoid patients exhibited a mild defect in polymorphonuclear leukocyte motility. Serum inhibitors of normal polymorphonuclear leukocyte chemotaxis were found in all types of leprosy, but sera from lepromatous and ENL patients were most inhibitory. Resting levels of Nitro Blue Tetrazolium reduction were normal in all three groups. Reconstitution of polymorphonuclear leukocyte cells from normal and ENL patients with ENL serum, however, showed increased Nitro Blue Tetrazolium reduction well above the normal range, whereas reconstitution with normal, lepromatous, and tuberculoid sera failed to increase Nitro Blue Tetrazolium reduction above the normal values.