Locally produced anti-phosphorylcholine and anti-oxidized low-density lipoprotein antibodies in gingival crevicular fluid from aggressive periodontitis patients

BACKGROUND: Sera from patients with periodontal attachment loss contain higher concentrations of IgG anti-phosphorylcholine (anti-PC) than sera from healthy subjects. Furthermore, a large proportion of plaque bacteria bear PC-containing surface antigens, implicating the oral flora as a source of immunogen for anti-PC. Additionally, anti-PC is cross-reactive with a variety of oral bacterial antigens and human antigens such as oxidized low-density lipoprotein (oxLDL). We hypothesized that, if the oral flora is a source of PC antigens, then we should be able to detect local anti-PC and anti-oxLDL production in gingival crevicular fluid (GCF). METHODS: To test this, we collected 66 GCF samples from 15 patients with aggressive periodontitis and examined both the GCF samples and serum samples for their content of IgG anti-PC, IgG anti-LDL, and IgG anti-oxLDL by enzyme-linked immunosorbent assay. We also determined levels of anti-tetanus toxoid (anti-TT) as a non-oral antigen control. Serum and GCF concentrations of serum albumin (HSA) were also determined for use as a dilution marker. A conservative GCF:serum antibody ratio of greater than 1.5 was considered to be evidence of local antibody production. RESULTS: For the non-oral antigen TT, only one out of 62 samples contained locally produced antibody. Eight out of 64 samples (7 from a single subject) demonstrated local production of anti-LDL. In contrast, 28 out of 66 samples demonstrated local production of anti-PC, and 47 out of 66 samples contained locally produced anti-oxLDL. It was observed that A. actinomycetemcomitans strains containing or devoid of PC could absorb anti-oxLDL from human sera. Although there was a correlation between the ratios of anti-PC and anti-oxLDL (Spearman's rho = 0.35, P = 0.0037), local production of both antibodies was found in only 17 out of 65 samples, indicating that these antibodies are not always reflective of reactivity to the same antigens. CONCLUSION: The local production of anti-PC and anti-oxLDL further implicates the oral flora as a source of antigen that may mediate immune reactions of relevance to cardiovascular and other systemic diseases.     

In vitro and in vivo activity of murine lymphokine-activated killer cells after cryopreservation

The in vitro and in vivo effects of cryopreservation on the cytotoxic activity of murine lymphokine-activated killer (LAK) cells were studied. LAK cells were generated by incubation of spleen lymphocytes of BALB/c mice for 3 days with recombinant interleukin-2 (rIL-2) and subsequent cryopreservation. Cytotoxicity was determined in a 51Cr release assay. After thawing, cytotoxic activity was reduced (40.4% 51Cr release at an effector:target cell ratio of 40:1 as compared to 68.5% 51Cr release before freezing) and could be restored to precryopreserved levels by reincubation with rIL-2 for 2 days after thawing (78.8% 51Cr release). These cells were then tested in BALB/c mice injected with RAW 112 cells, a pre-B-cell lymphoma line. The results demonstrate that the survival rate of mice injected with cryopreserved and restimulated LAK cells (50% survival greater than 180 days after injection) did not differ significantly from that of mice injected with fresh unfrozen LAK cells (60% survival greater than 120 days, 50% survival greater than 180 days). Cryopreserved LAK cells have potential use in adoptive immunotherapy.     

Emergence of Gentamicin-Resistant Klebsiella in a General Hospital

Gentamicin had been in use in a general hospital for over 7 years before any gentamicin-resistant Klebsiella were observed. In 1974 and 1975, nine different gentamicin-resistant serobiotypes of Klebsiella were isolated from 35 patients. The first strain to appear had R-factor-mediated gentamicin resistance, and it infected 19 patients during a period of almost 2 years, spreading largely by case-to-case infection in patients with urinary catheters. It appeared to lose the capacity to transfer its gentamicin resistance after it had infected five of the patients. We had previously isolated on the same ward a gentamicin-susceptible Klebsiella of identical type, and it was found to be capable of acquiring an R-factor for gentamicin resistance. All of the other types of gentamicin-resistant Klebsiella infected few patients and did not persist in the hospital; four of them had R-factor-mediated resistance to gentamicin and all four, as did the original strain, cotransferred kanamycin, neomycin, and tobramycin resistance. Every gentamicin-resistant Klebsiella was susceptible to amikacin and netilmicin.     

Hyperglycemia and renin-dependent hypertension synergize to model diabetic nephropathy

Rodent models exhibit only the earliest features of human diabetic nephropathy, which limits our ability to investigate new therapies. Hypertension is a prerequisite for advanced diabetic nephropathy in humans, so its rarity in typical rodent models may partly explain their resistance to nephropathy. Here, we used the Cyp1a1mRen2 rat, in which the murine renin-2 gene is incorporated under the Cytochrome P4501a1 promoter. In this transgenic strain, administration of low-dose dietary indole-3-carbinol induces moderate hypertension. In the absence of hypertension, streptozotocin-induced diabetes resulted in a 14-fold increase in albuminuria but only mild changes in histology and gene expression despite 28 weeks of marked hyperglycemia. In the presence of induced hypertension, hyperglycemia resulted in a 500-fold increase in albuminuria, marked glomerulosclerosis and tubulointerstitial fibrosis, and induction of many of the same pathways that are upregulated in the tubulointerstitium in human diabetic nephropathy. In conclusion, although induction of diabetes alone in rodents has limited utility to model human diabetic nephropathy, renin-dependent hypertension and hyperglycemia synergize to recapitulate many of the clinical, histological, and gene expression changes observed in humans.     

BOLD responses to stimuli: dependence on frequency, stimulus form, amplitude, and repetition rate

A quantitative theory is developed for the relationship between stimulus and the resulting blood oxygen level-dependent (BOLD) functional MRI signal. The relationship of stimuli to neuronal activity during evoked responses is inferred from recent physiology-based quantitative modeling of evoked response potentials (ERPs). A hemodynamic model is then used to calculate the BOLD response to neuronal activity having the form of an impulse, a sinusoid, or an ERP-like damped sinusoid. Using the resulting equations, the BOLD response is analyzed for different forms, frequencies, and amplitudes of stimuli, in contrast with previous research, which has mostly concentrated on sustained stimuli. The BOLD frequency response is found to be closely linear in the parameter ranges of interest, with the form of a low-pass filter with a weak resonance at approximately 0.07 Hz. An improved BOLD impulse response is systematically obtained which includes initial dip and post-stimulus undershoot for some parameter ranges. It is found that the BOLD response depends strongly on the precise temporal course of the evoked neuronal activity, not just its peak value or typical amplitude. Indeed, for short stimuli, the linear BOLD response is closely proportional to the time-integrated activity change evoked by the stimulus, regardless of amplitude. It is concluded that there can be widely differing proportionalities between BOLD and peak activity, that this is the likely reason for the low level of correspondence seen experimentally between ERP sources and BOLD measurements and that non-BOLD measurements, such as ERPs, can be used to correct for this effect to obtain improved activity estimates. Finally, stimulus sequences that optimize the signal-to-noise ratio in event-related BOLD fMRI (efMRI) experiments are derived using the hemodynamic transfer function.     

Perceptions of voluntary medical male circumcision among circumcising and non-circumcising communities in Malawi

Three randomised controlled trials in Africa indicated that voluntary medical male circumcision (VMMC) is an effective method to reduce a man's risk of becoming infected through sex with an HIV-positive female partner. The success of recent public health initiatives to increase numbers of circumcised men in Malawi has been very limited. We conducted in-depth interviews and focus group discussions (FGDs) with men, women and male adolescents from non-circumcising and circumcising communities in southern Malawi to better understand their beliefs about male circumcision and the promotion of VMMC for HIV prevention. Results revealed that beliefs about male circumcision, in general, are strongly mediated by Malawian culture and history. Participants have attempted to develop a new meaning for circumcision in light of the threat of HIV infection and the publicised risk reduction benefits of VMMC. Several study participants found it difficult to distinguish VMMC from traditional circumcision practices (jando and lupanda), despite awareness that the new form of circumcision was an expression of (western) modern medicine performed largely for public health purposes. Greater recognition of background cultural beliefs and practices could inform future efforts to promote medical male circumcision as an HIV prevention strategy in this context.