Activated CD8(+) T cells from aged mice exhibit decreased activation-induced cell death

To uncouple the defects of activation and apoptosis of T cells from aged mice, we used anti-CD3 plus IL-2 stimulation to induce an activation response and analyzed the subsequent activation-induced cell death (AICD) response of T cells from 16-month-old mice. The results herein demonstrate that T cells from 16-month-old mice could be activated by anti-CD3-induced activation signals but exhibited distinct phenotypic and functional features compared to young (2-month-old) mice. These include a decrease in AICD, a delayed entry into the cell cycle, and a decreased telomerase activity. The decreased AICD of T cells from 16-month-old mice is associated with a decreased expression of Fas and Fas ligand (FasL), decreased susceptibility to anti-Fas-induced apoptosis, and an increased expansion of a CD8(+) T-cell population. Prior to activation, these T cells exhibit a phenotype that is CD44(hi)CD62L(hi). After stimulation, these T cells produced high levels of the pro-inflammatory cytokine, IFN-gamma, and developed an increased population of IFN-gamma(+)IFN-gamma R(-) T cells. Our results suggest that there is a dysregulation in T-cell homeostasis in aged mice associated with a decrease in AICD of CD8(+) T cells.     

Protective cytotoxic T lymphocyte responses against paramyxoviruses induced by epitope-based DNA vaccines: involvement of IFN-gamma

Plasmid DNA vectors have been constructed with minigenes encoding a single cytotoxic T lymphocyte (CTL) epitope from either the M2 protein of respiratory syncytial virus (RSV) or from the nucleoprotein of measles virus (MV) with or without a signal sequence (also called secretory or leader sequence). Following intradermal immunization, plasmids in which the CTL epitopes were expressed in-frame with the signal sequence were more effective at inducing peptide- and virus- specific CTL responses than plasmids expressing CTL epitopes without the signal sequence. This immunization resulted in protection against MV-induced encephalitis and a significant reduction in viral load following RSV challenge. The reduction of viral load following RSV challenge was abrogated by prior injection with anti-IFN-gamma antibodies. These results highlight the ability of epitope-based DNA immunization to induce protective immune responses to well-defined epitopes and indicate the potential of this approach for the development of vaccines against infectious diseases.      

Drosophila mutants with progressive atrophy in dorsal longitudinal muscles

We have characterized six chemically induced mutations of the Drosophila dlm-defective (d l m d) gene. The mutants are flightless, but they have an otherwise normal appearance. By electron microscopic examination, a focal atrophy was found in their dorsal longitudinal muscle (DLM) fibers, but no abnormalities in nerve conduction or synaptic transmission were detected by electrophysiological tests. The nerve-evoked muscle spike also seemed to be normal, except that the resting potential of DLM in mutant flies was lower and their membrane excitability was higher than those in the wild type flies. The possible causes of the DLM degeneration in this strain are discussed.     

Genetic segregation of spontaneous erosive arthritis and generalized autoimmune disease in the BXD2 recombinant inbred strain of mice

The BXD2 strain of mice is one of approximately 80 BXD recombinant inbred (RI) mouse strains derived from an intercross between C57BL/6J (B6) and DBA/2J (D2) strains. We have discovered that adult BXD2 mice spontaneously develop generalized autoimmune disease, including glomerulonephritis (GN), increased serum titres of rheumatoid factor (RF) and anti-DNA antibody, and a spontaneous erosive arthritis characterized by mononuclear cell infiltration, synovial hyperplasia, and bone and cartilage erosion. The features of lupus and arthritis developed by the BXD2 mice segregate in F2 mice generated by crossing BXD2 mice with the parental B6 and D2 strains. Genetic linkage analysis of the serum levels of anti-DNA and RF by using the BXD RI strains shows that the serum titers of anti-DNA and RF were influenced by a genetic locus on mouse chromosome (Chr) 2 near the marker D2Mit412 (78 cm, 163 Mb) and on Chr 4 near D4Mit146 (53.6 cm, 109 Mb), respectively. Both loci are close to the B-cell hyperactivity, lupus or GN susceptibility loci that have been identified previously. The results of our study suggest that the BXD2 strain of mice is a novel model for complex autoimmune disease that will be useful in identifying the mechanisms critical for the immunopathogenesis and genetic segregation of lupus and erosive arthritis.     

Status of hepatitis B virus DNA in hepatocellular carcinoma: a study based on paired tumor and nontumor liver tissues

To investigate the hepatitis B virus (HBV) DNA status in the liver when hepatocellular carcinoma (HCC) has developed, 35 paired nontumorous and tumorous liver tissues from 27 hepatitis B surface antigen (HBsAg)-seropositive and 8 HBsAg-negative patients with HCC were studied by Southern blot analysis. The hybridization patterns of HBV DNA were different in the nontumor and tumor parts in 26 (96.3%) of the 27 HBsAg-positive patients. In the nontumor parts, integration of HBV DNA into the host genome was significantly less when compared to the tumor parts (15/27 vs. 25/27, P less than 0.05), whereas free replicative viral forms were significantly more frequent (17/27 vs. 7/27). The integrated HBV DNA in the nontumor parts showed discrete band patterns in the majority of cases (13/15). Hepatitis B e antigen (HBeAg) was significantly associated with the expression of free replicative forms of HBV DNA in the tumor tissues. An integrated HBV DNA sequence was detected in the tumor part of one HBsAg-negative patient, but not in her nontumor counterpart. Our observation that discrete integrated HBV DNAs are present in the nontumor part, representing subclinical clonal expansion that precedes the development of HCC, suggests the risk of future new tumor growth from these cell clones.     

Cloning of the fusion gene of rinderpest virus: comparative sequence analysis with other morbilliviruses

We have cloned the cDNA of the fusion (F) gene of the virulent (Kabete O) strain of rinderpest virus and provided a comparative analysis of its sequence with that of the F genes of measles and distemper viruses. The gene has an open reading frame of 2241 nucleotides with two potential initiation codons in-frame. Use of the first ATG would produce a polypeptide 747 amino acids long with a calculated molecular weight of 81,068. However, we suggest that the second ATG is used to generate the Fo protein, which is 546 amino acids long with a calculated molecular weight of 58,754. During maturation, the cleavage of F0 gives rise to the functional F1 and F2 polypeptides. The F1 polypeptide is 438 amino acids long and has a calculated molecular weight of 46,791, with a single (potential) glycosylation site in its cytoplasmic domain. The F2 polypeptide, probably 89 amino acids long after the signal sequence is cleaved, is estimated to be 9,800 Da and has three potential glycosylation sites. There is a divergence of 18.7% in amino acid sequences between rinderpest and measles virus F0 polypeptides; between distemper and rinderpest viruses the divergence is 31.8%. No significant homology in nucleotide sequences of rinderpest DNA to measles or distemper DNA was found in the 5' and 3' untranslated regions.     

Effect of peroral immunization of humans with Streptococcus mutans on induction of salivary and serum antibodies and inhibition of experimental infection

Naturally occurring antibodies reactive with Streptococcus mutans whole cells were assayed in whole saliva, parotid saliva, and blood samples collected from eight human volunteers. The levels and serotypes of indigenous S. mutans in plaque and whole saliva samples were also determined. After baseline sampling the teeth were cleaned and the subjects were inoculated with streptomycin-resistant S. mutans strains Ingbritt (serotype c) and OMZ65 (serotype g). The level of implantation and duration of colonization were determined in plaque and saliva, and antibodies reactive with these strains were monitored in saliva and serum. After the implanted bacteria were shed, the subjects wee immunized by the daily ingestion of an enteric-coated capsule containing 25 mg of Formalin-killed, freeze-dried OMZ65 cells for 3 days and inoculation was repeated. The levels of antibodies and of implantation and the duration of colonization were monitored as before. One month after the bacteria could no longer be detected, the immunization and inoculation cycle was repeated except that the subjects were immunized for 7 days. Five of the eight subjects were successfully colonized by strains Ingbritt and OMZ65. The remaining three did not become colonized with either strain. Strain OMZ65 implanted at a higher level than did strain Ingbritt. Oral immunization did not result in a detectable antibody response in saliva or serum to whole bacterial cells. However, after both the first and second immunizations there were marked reductions in the peak levels of infection and the duration of colonization of both OMZ65 and Ingbritt.     

Cannabinoid-induced presynaptic inhibition at the primary afferent trigeminal synapse of juvenile rat brainstem slices

Systemic or intraventricular administration of cannabinoids causes analgesic effects, but relatively little is known for their cellular mechanism. Using brainstem slices with the mandibular nerve attached, we examined the effect of cannabinoids on glutamatergic transmission in superficial trigeminal caudal nucleus of juvenile rats. The exogenous cannabinoid receptor agonist WIN 55,212-2 (WIN), as well as the endogenous agonist anandamide, hyperpolarized trigeminal caudal neurones and depressed the amplitude of excitatory postsynaptic potentials (EPSPs) or currents (EPSCs) monosynaptically evoked by stimulating mandibular nerves in a concentration-dependent manner. The inhibitory action of WIN was blocked or fully reversed by the CB₁ receptor antagonist SR 141716A. WIN had no effect on the amplitude of miniature excitatory postsynaptic currents (mEPSCs) recorded in the presence of tetrodotoxin or cadmium. The inhibitory effect of WIN on EPSCs was greater for those with longer synaptic latency, suggesting that cannabinoids have a stronger effect on C-fibre EPSPs than on Aδ-fibre EPSPs. Ba²⁺ (100 μ m ) blocked the hyperpolarizing effect of cannabinoids, but did not affect their inhibitory effect on EPSPs. The N-type Ca²⁺ channel blocker ω-conotoxin GVIA (ω-CgTX) occluded the WIN-mediated presynaptic inhibition, whereas the P/Q-type Ca²⁺ channel blocker ω-agatoxin TK (ω-Aga) had no effect. These results suggest that cannabinoids preferentially activate CB₁ receptors at the nerve terminal of small-diameter primary afferent fibres. Upon activation, CB₁ receptors may selectively inhibit presynaptic N-type Ca²⁺ channels and exocytotic release machinery, thereby attenuating the transmitter release at the trigeminal nociceptive synapses.     

Increasing trend of Cesarean deliveries in HIV-infected women in the United States from 1994 to 2000

BACKGROUND: Meta-analysis and randomized clinical trial results reported in June 1998 indicated a significant reduction in perinatal HIV transmission rates among mothers undergoing a cesarean section (C-section). OBJECTIVE: The objective of this study was to examine recent trends in and factors associated with C-section deliveries among HIV-infected women in the United States. DESIGN: A multisite pediatric medical record review of a cohort of HIV-exposed and HIV-infected infants in the Pediatric Spectrum of HIV Disease (PSD) Cohort study (n = 6467) and the national Pediatric HIV/AIDS Reporting System (HARS) (n = 8,306) was conducted. SETTING/PATIENTS: All infants born between 1994 and 2000 to HIV-positive mothers referred to the PSD study or to a Pediatric HARS hospital or clinic site were enrolled. RESULTS: The proportion of deliveries by C-section was steady at about 20% from 1994 through June 1998. From July 1998 through December 2000, this proportion increased to 44% in the PSD study and to nearly 50% in the Pediatric HARS. On analysis by multiple logistic regression, delivery of infants by C-section was associated with the release of study results (OR = 2.83), delivery in four PSD sites in reference to Texas (OR: 2.02-1.43), having private medical care reimbursement (OR = 1.62), and having maternal prenatal care (OR = 1.43). CONCLUSIONS: The PSD and Pediatric HARS data demonstrate a sharp increase in C-section rates mainly among HIV-infected women in the United States after the release of the meta-analysis and randomized clinical trial results in 1998. This finding highlights the rapid impact of study results on obstetric practice. It underscores the critical role of prenatal care in offering perinatal interventions such as scheduled C-section when indicated to reduce the likelihood of HIV transmission.