Characterization of the rat neutrophil formyl peptide chemotaxis receptor.

Numerous synthetic N-formylated peptides, believed to be the analogs of the naturally occurring initiating signal peptides produced by bacteria, are potent chemotactic agents for phagocytic cells in several species. The authors have characterized the receptor with moderately high affinity for the chemotactic peptide f-Met-Leu-[3H]Phe on the rat peritoneal neutrophils. When neutrophils are incubated with f-Met-Leu-[3H]Phe at 24 C, the binding is saturable and reversible. The receptor on the inflammatory rat neutrophils has an equilibrium dissociation constant (KD) of 3.4 x 10(-8) M at 24 C, and there are approximately 65,000 sites per cell. In addition, the potency of several of these chemotactic peptides in inducing lysosomal enzyme secretion and superoxide production correlated well with their ability to compete with f-Met-Leu-[3H]Phe for receptor binding. Structure activity studies further demonstrate that the fine specificity of the formyl peptide receptor has been conserved across species lines.     

Incidence of and risk factors for lipoatrophy (abnormal fat loss) in ambulatory HIV-1-infected patients

To identify clinical factors associated with the incidence of HIV-1-associated lipoatrophy, HIV-1-infected patients in the HIV Outpatient Study (HOPS) were prospectively evaluated for clinical signs of lipoatrophy at two visits about 21 months apart. Development of lipoatrophy was analyzed in stratified and multivariate analyses for its relationship to immunologic, virologic, clinical, and drug treatment information for each patient. Of 337 patients with no lipoatrophy at Survey 1, 44 (13.1%) developed moderate or severe lipoatrophy between the two surveys. In multivariate analyses, significant risk factors for incident lipoatrophy were white race (OR = 5.2; 95% CI: 1.9-17.1; =.003), CD4 T-lymphocyte count at Survey 2 less than 100 cells/mm3 (OR = 4.2; 95% CI: 1.3-13.1; =.013), and body mass index (BMI) less than 24 kg/m2 (OR = 2.4; 95% CI: 1.1-5.4; =.024). Analyses that controlled for the severity of HIV illness demonstrated no significant association with use of or time on any antiretroviral agent or class of agents and the development of lipoatrophy. Some host factors and factors associated with previous or current severity of HIV infection, especially CD4 T-lymphocyte cell count, appeared to have the strongest association with incidence of lipoatrophy.     

Cytotoxicity of tumor necrosis factor-alpha for human umbilical vein endothelial cells

Human umbilical vein endothelial cells were examined for sensitivity to killing by human recombinant tumor necrosis factor-alpha (TNF-alpha). Treatment of the cells with concentrations of TNF-alpha up to 50 ng/ml for 18 hours did not produce evidence of cytotoxicity. However, a marked cytotoxic effect was found when TNF-alpha pretreated cells were incubated in Hanks' balanced salt solution for a further 4 hours. Exposure of the cells to heat-inactivated or antibody-neutralized TNF-alpha did not result in cytotoxicity. Human recombinant interleukin-1 also lysed endothelial cells under the same conditions, whereas human recombinant macrophage-colony stimulating factor did not. Inclusion of superoxide dismutase, catalase, or soybean trypsin inhibitor in the culture medium during the time of endothelial cell exposure to TNF-alpha had no protective effects. Likewise, allopurinol (a xanthine oxidase inhibitor) and nordihydro-guaiaretic acid (a lipoxygenase inhibitor) were not protective under the same conditions. In contrast, the ferric iron chelator deferoxamine mesylate and three different cyclooxygenase inhibitors provided significant protection against TNF-alpha induced cytotoxicity. When human dermal fibroblasts and human squamous epithelial cells were used in place of the umbilical vein endothelial cells, these cells were resistant to TNF-alpha mediated killing. These findings demonstrate that under the experimental conditions employed, TNF-alpha is cytotoxic for human umbilical vein endothelial cells. This may have implications in a number of in vivo situations in which TNF-alpha is thought to play a role.     

Haemophilus influenzae meningitis. A national study of secondary spread in household contacts.

To determine the risk of severe Haemophilus influenzae illness among household contacts of patients with H. influenzae meningitis, we studied prospective data obtained in 19 states from January 1, 1977, to June 30, 1978. H. influenzae meningitis was reported in 1403 patients, and 1147 (82 per cent) of the exposed families were investigated for the occurrence of H. influenzae disease within 30 days after its onset in the index patient. During this interval, nine of 1687 household contacts (0.5 per cent) under the age of six years had systemic disease confirmed to be caused by H. influenzae Type b. The risk in children less than one year of age was 6 per cent, and the risk in those less than four years of age was 2.1 per cent. None of 2624 contacts above the age of five was affected. In the 30 days after onset of meningitis, the risk of this infection alone, aside from other types of serious H. influenzae disease, is 585 times greater in household contacts than the age-adjusted risk in the general population. The risk of H. influenzae disease in household contacts under six years of age is similar to the risk of secondary meningococcal disease in all household contacts--indicating a need for effective antimicrobial prophylaxis.     

Origin and fate of fetuin-containing neurons in the developing neocortex of the fetal sheep

Summary The development of the neocortex has previously been extensively studied in carnivores (cat and ferret), rodents (rat and mouse) and primates (monkey and human). In these species, it has been shown that the initial population of cells migrating from the ventricular zone forms the primordial plexiform layer. This is subsequently split into marginal zone and subplate zone by the insertion of later-migrating cells into the primordial plexiform layer, to form the cortical plate proper. Many of the cells derived from the split primordial plexiform layer are transient. The neurons of the subplate zone are found in the deeper part of layer VI, and white matter deep to layer VI in the more mature cortex; most of these neurons disappear by adulthood. [³H]-thymidine labelling in the present study has shown a similar pattern of neocortical development in Artiodactyla (sheep). In addition it has been shown that the previously described staining of subplate and cortical plate cells for the fetal protein fetuin indicates that fetuin is a useful marker for a proportion of this transient population of neurons and defines its extent in neocortical development more clearly. Dividing cells were labelled by a single intra-amniotic injection of [³H]-thymidine at E26 to E35 (birth is at E150). The brains were subsequently examined at E40 or E80 for [³H]-thymidine labelling and fetuin staining by a combination of autoradiography and immunocytochemistry. The earliest generated neocortical cells detected in this study (E26) were found in two layers by E40, the outer marginal zone and inner subplate zone. Neurons of the marginal zone were generated up to E28; those of the early subplate zone were generated up to E31. The cortical plate proper was generated by cells born on E32 and later. This sequence is similar to that described in other species, especially the cat. A proportion of the early-generated neurons in the marginal zone, subplate zone and early cortical plate stained for fetuin. By E80 these earliest-generated, fetuin-positive cells were found in the white matter deep to the forming neocortical layers and in layer VI. In adult brains no fetuin-positive neurons could be identified in the neocortex, and neurons had almost entirely disappeared from the white matter. The fetal glycoprotein fetuin seems to be specifically associated with a population of cells that has the same developmental history as the transient marginal zone and subplate neurons described in other species. However, the distribution of fetuin-containing neurons is more extensive and includes some of the neurons within the cortical plate itself. Thus in addition to being a marker for a proportion of the transient marginal zone and subplate cells, the presence of fetuin in subplate and cortical plate neurons, given the trophic properties attributed to fetuin, may indicate its involvement in early stages of synaptogenesis and connectivity in the developing neocortex.     

HIV infection among patients in U.S. acute care hospitals. Strategies for the counseling and testing of the hospital patients. The Hospital HIV Surveillance Group.

BACKGROUND. Routine, voluntary testing of hospital patients for the human immunodeficiency virus (HIV) has been proposed in order to identify those with early HIV infection in a setting where there is ready access to counseling, appropriate clinical referral, evaluation, and therapy. We studied the pattern of HIV infection among patients in 20 U.S. hospitals, in order to evaluate possible national strategies for the routine, voluntary HIV counseling and testing of hospital patients. METHODS. Blood specimens remaining after clinical use from a systematically selected sample of patients at 20 hospitals in 15 U.S. cities were tested anonymously for antibody to HIV type 1 (HIV-1). Multivariate regression was used to determine which variables best predicted HIV seroprevalence in individual hospitals. Using these data, we estimated the number of HIV-positive patients in all U.S. hospitals and considered the efficiency of routine counseling and testing in different subgroups of patients and hospitals. RESULTS. From September 1989 through October 1991, 9286 of 195,829 specimens (4.7 percent) were positive for HIV-1 in the 20 hospitals. The seroprevalence of HIV at these institutions ranged from 0.2 percent to 14.2 percent. Among HIV-positive patients, 32 percent had symptomatic HIV infection or the acquired immunodeficiency syndrome (AIDS) at the time of admission or evaluation. In the 20 hospitals, HIV seroprevalence was 10.4 times (95 percent confidence interval, 8.8 to 12.0) the AIDS-diagnosis rate (the annual number of patients with new diagnoses of AIDS per 1000 discharges in 1990). In a multivariate model that included 13 hospital-specific variables, only the AIDS-diagnosis rate was associated with the hospital-specific HIV-seroprevalence rate (P less than 0.001). Using these data and the AIDS-diagnosis rates for all U.S. acute care hospitals, we estimated that 225,000 HIV-positive persons were hospitalized (95 percent confidence interval, 190,000 to 260,000) in all 5558 such hospitals in 1990, including 163,000 persons presenting with conditions other than HIV or AIDS (95 percent confidence interval, 130,000 to 196,000). In 1990, in 593 U.S. hospitals with AIDS-diagnosis rates of 1.0 or more per 1000 discharges, HIV testing of patients 15 to 54 years old (3 million patients, or 12.0 percent of all patients in U.S. acute care hospitals) would have identified an estimated 68 percent of all HIV-positive patients (110,000 patients) who were admitted with conditions other than symptomatic HIV infection or AIDS. CONCLUSIONS. We estimate that about 225,000 HIV-positive persons were hospitalized in 1990, of whom only one third were admitted for symptomatic HIV infection or AIDS. Routine, voluntary HIV testing of patients 15 to 54 years old in hospitals with 1 or more patients with newly diagnosed AIDS per 1000 discharges per year could potentially have identified as many as 110,000 patients with HIV infection that was previously unrecognized.     

Small marker chromosome identification in metaphase and interphase using centromeric multiplex fish (CM-FISH)

Multicolor karyotyping procedures, such as multiplex fluorescence in situ hybridization (M-FISH), spectral karyotyping, or color-changing karyotyping, can be used to detect chromosomal rearrangements and marker chromosomes in prenatal diagnosis, peripheral blood cultures, leukemia, and solid tumors, especially in cases where G-banding is not sufficient. A regular M-FISH analysis requires relatively large amounts of labeled DNA (microgram quantities), is not informative in interphase nuclei, hybridization can take up to 2 to 3 days, and unlabeled human chromosome-painting probes are not available commercially. Unique probes (plasmids, PAC), specific for centromeric or subtelomeric chromosomal regions, can replace the painting probes in M-FISH to address specific issues, such as the identification of marker chromosomes and aneuploidies. A set of plasmid probes carrying repetitive sequences specific for the alpha-satellite region of all human chromosomes were combined in a metaphase assay and an interphase assay, allowing identification of aneuploidies in one hybridization step, on a single cytogenetic slide. The fluorophore-dUTP and the labeled antibodies required to label and detect the DNA probes can be prepared in any laboratory. All DNA probes can be easily isolated and labeled using common molecular cytogenetic procedures. Because of the repetitive nature of the probes, hybridization time is short, usually less than 1 hour, and the analysis can be performed with nonspecialized image-processing software.     

Primary and recurrent cytomegalovirus infections have different effects on human herpesvirus-6 antibodies in immunosuppressed organ graft recipients: absence of virus cross-reactivity and evidence for virus interaction.

The relationship between serum antibodies to human herpesvirus-6 (HHV-6) and cytomegalovirus (CMV) infection was studied in immunosuppressed adult organ graft recipients all of whom had IgG to both HHV-6 and Epstein-Barr virus capsid antigen (EBVCA) before operation and who had received an organ or organs from HHV-6 seropositive donors. In primary CMV infection the titre of IgG to HHV-6 rose substantially (between 32- and 512-fold) in eight out of eight patients whereas IgG to EBVCA only rose 32-fold in two patients. Moreover, the HHV-6 responses coincided closely with the CMV seroconversion. Serum absorption studies gave no evidence for antibody cross-reaction between CMV and HHV-6 because the CMV antibody titre could be reduced specifically without affecting HHV-6 antibody titres and vice versa. In recurrent CMV infection, HHV-6 antibody levels rose (32-fold) in three out of eight patients but these changes did not coincide with the CMV antibody response. Similarly, in the complete absence of CMV infection, five out of eight patients showed antibody rises to HHV-6 (between four- and 16-fold). IgG titres to EBVCA were stable in both these groups of patients. It is concluded that there is serological evidence (rising titre greater than or equal to four-fold) for genuine HHV-6 reactivation or, alternatively, for reinfection in 16 out of the 24 patients. This phenomenon was most frequent in primary CMV infection where the largest HHV-6 antibody responses were seen probably because of an, as yet, undetermined interaction between the two viruses.     

Characterization of the dominant autoreactive T-cell epitope in spontaneous autoimmune haemolytic anaemia of the NZB mouse

NZB mice spontaneously develop autoimmune haemolytic anaemia (AIHA) due to a T helper-dependent autoantibody response against the erythrocyte anion channel protein, Band 3. Here, we characterize the recognition of the Band 3 sequence 861-874, which carries the dominant, I-E(d)-restricted T cell epitope. The ability of N and C-terminal truncated versions of peptide 861-874 to elicit NZB splenic T-cell proliferation indicated that the core epitope spans residues 862-870. Next, a set of alanine substitution analogues was tested to determine which residues functioned either as MHC anchor or TCR contact residues. A combination of proliferation and MHC:peptide binding assays identified residues 862(L), 864(V), 865(L), and 869(K) as I-E(d) anchor residues, and 868(V) as the only TCR contact residue. The ability of the wild-type sequence 861-874 to compete with a high affinity reference peptide for binding to I-E(d) indicates that the escape of pathogenic NZB T cells from purging of the autoreactive repertoire cannot be attributed to ineffective presentation of peptide 861-874 by its restricting element. It will now be possible to design altered peptide ligands of Band 3 861-874, in order to further dissect the mechanisms responsible for the maintenance and loss of T cell tolerance to RBC autoantigens, and to modulate the immune response in AIHA.     

Visual perception in women during the menstrual cycle

Twelve females were tested at four times during the menstrual cycle with a visual detection task and a visual pattern discrimination task. Mood levels and confidence ratings were evaluated for each session. In addition to the behavioral testing, plasma samples were collected and radioimmunoassayed for estradiol, progesterone, luteinizing hormone, and follicle stimulating hormone levels. Visual detection fluctuated significantly during the menstrual cycle with impaired performance occurring at the premenstrual session. In contrast to previous reports, the impaired performance was not related to lowered confidence ratings or to mood levels.