NMDA spikes in basal dendrites of cortical pyramidal neurons

Basal dendrites are a major target for synaptic inputs innervating cortical pyramidal neurons. At present little is known about signal processing in these fine dendrites. Here we show that coactivation of clustered neighbouring basal inputs initiated local dendritic spikes, which resulted in a 5.9 +/- 1.5 mV (peak) and 64.4 +/- 19.8 ms (half-width) cable-filtered voltage change at the soma that amplified the somatic voltage response by 226 +/- 46%. These spikes were accompanied by large calcium transients restricted to the activated dendritic segment. In contrast to conventional sodium or calcium spikes, these spikes were mediated mostly by NMDA (N-methyl-D-aspartate) receptor channels, which contributed at least 80% of the total charge. The ionic mechanism of these NMDA spikes may allow 'dynamic spike-initiation zones', set by the spatial distribution of glutamate pre-bound to NMDA receptors, which in turn would depend on recent and ongoing activity in the cortical network. In addition, NMDA spikes may serve as a powerful mechanism for modification of the cortical network by inducing long-term strengthening of co-activated neighbouring inputs.

Action potential initiation and propagation in rat neocortical pyramidal neurons

1. Initiation and propagation of action potentials evoked by extracellular synaptic stimulation was studied using simultaneous dual and triple patch pipette recordings from different locations on neocortical layer 5 pyramidal neurons in brain slices from 4-week-old rats (P26-30) at physiological temperatures. 2. Simultaneous cell-attached and whole-cell voltage recordings from the apical trunk (up to 700 microns distal to the soma) and the soma indicated that proximal synaptic stimulation (layer 4) initiated action potentials first at the soma, whereas distal stimulation (upper layer 2/3) could initiate dendritic regenerative potentials prior to somatic action potentials following stimulation at higher intensity. 3. Somatic action potentials, once initiated, propagated back into the apical dendrites in a decremented manner which was frequency dependent. The half-width of back propagating action potentials increased and their maximum rate of rise decreased with distance from the soma, with the peak of these action potentials propagating with a conduction velocity of approximately 0.5 m s-1. 4. Back-propagation of action potentials into the dendritic tree was associated with dendritic calcium electrogenesis, which was particularly prominent during bursts of somatic action potentials. 5. When dendritic regenerative potentials were evoked prior to somatic action potentials, the more distal the dendritic recording was made from the soma the longer the time between the onset of the dendritic regenerative potential relative to somatic action potential. This suggested that dendritic regenerative potentials were initiated in the distal apical dendrites, possibly in the apical tuft. 6. At any one stimulus intensity, the initiation of dendritic regenerative potentials prior to somatic action potentials could fluctuate, and was modulated by depolarizing somatic or hyperpolarizing dendritic current injection. 7. Dendritic regenerative potentials could be initiated prior to somatic action potentials by dendritic current injections used to simulate the membrane voltage change that occurs during an EPSP. Initiation of these dendritic potentials was not affected by cadmium (200 microM), but was blocked by TTX (1 microM). 8. Dendritic regenerative potentials in some experiments were initiated in isolated from somatic action potentials. The voltage change at the soma in response to these dendritic regenerative events was small and subthreshold, showing that dendritic regenerative events are strongly attenuated as they spread to the soma. 9. Simultaneous whole-cell recordings from the axon initial segment and the soma indicated that synaptic stimulation always initiated action potentials first in the axon. The further the axonal recording was made from the soma the greater the time delay between axonal and somatic action potentials, indicating a site of action potential initiation in the axon at least 30 microns distal to the soma. 10. Simultaneous whole-cell recordings from the apical dendrite, soma and axon initial segment showed that action potentials were always initiated in the axon prior to the soma, and with the same latency difference, independent of whether dendritic regenerative potentials were initiated or not. 11. It is concluded that both the apical dendrites and the axon of neocortical layer 5 pyramidal neurons in P26-30 animals are capable of initiating regenerative potentials. Regenerative potentials initiated in dendrites, however, are significantly attenuated as they spread to the soma and axon. As a consequence, action potentials are always initiated in the axon before the soma, even when synaptic activation is intense enough to initiate dendritic regenerative potentials. Once initiated, the axonal action potentials are conducted orthogradely into the axonal arbor and retrogradely into the dendritic tree.

Calcium action potentials restricted to distal apical dendrites of rat neocortical pyramidal neurons

1. Simultaneous whole-cell voltage and Ca2+ fluorescence measurements were made from the distal apical dendrites and the soma of thick tufted pyramidal neurons in layer 5 of 4-week-old (P28-32) rat neocortex slices to investigate whether activation of distal synaptic inputs can initiate regenerative responses in dendrites. 2. Dual whole-cell voltage recordings from the distal apical trunk and primary tuft branches (540-940 microns distal to the soma) showed that distal synaptic stimulation (upper layer 2) evoking a subthreshold depolarization at the soma could initiate regenerative potentials in distal branches of the apical tuft which were either graded or all-or-none. These regenerative potentials did not propagate actively to the soma and axon. 3. Calcium fluorescence measurements along the apical dendrites indicated that the regenerative potentials were associated with a transient increase in the concentration of intracellular free calcium ([Ca2+]i) restricted to distal dendrites. 4. Cadmium added to the bath solution blocked both the all-or-more dendritic regenerative potentials and local dendritic [Ca2+]i transients evoked by distal dendritic current injection. Thus, the regenerative potentials in distal dendrites represent local Ca2+ action potentials. 5. Initiation of distal Ca2+ action potentials by a synaptic stimulus required coactivation of AMPA- and NMDA-type glutamate receptor channels. 6. It is concluded that in neocortical layer 5 pyramidal neurons of P28-32 animals glutamatergic synaptic inputs to the distal apical dendrites can be amplified via local Ca2+ action potentials which do not reach threshold for axonal AP initiation. As amplification of distal excitatory synaptic input is associated with a localized increase in [Ca2+]i these Ca2+ action potentials could control the synaptic efficacy of the distal cortico-cortical inputs to layer 5 pyramidal neurons.

Matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry in lipid and phospholipid research

The interest in the analysis of lipids and phospholipids is continuously increasing due to the importance of these molecules in biochemistry (e.g. in the context of biomembranes and lipid second messengers) as well as in industry. Unfortunately, commonly used methods of lipid analysis are often time-consuming and tedious because they include previous separation and/or derivatization steps. With the development of "soft-ionization techniques" like electrospray ionization (ESI) or matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF), mass spectrometry became also applicable to lipid analysis. The aim of this review is to summarize so far available experiences in MALDI-TOF mass spectrometric analysis of lipids. It will be shown that MALDI-TOF MS can be applied to all known lipid classes and the characteristics of individual lipids will be discussed. Additionally, some selected applications in medicine and biology, e.g. mixture analysis, cell and tissue analysis and the determination of enzyme activities will be described. Advantages and disadvantages of MALDI-TOF MS in comparison to other established lipid analysis methods will be also discussed.

Degradative action of reactive oxygen species on hyaluronan

Many human diseases are associated with harmful action of reactive oxygen species (ROS). These species are involved in the degradation of essential tissue or related components. One of such components is synovial fluid that contains a high-molecular-weight polymer--hyaluronan (HA). Uninhibited and/or inhibited hyaluronan degradation by the action of various ROS has been studied in many in vitro models. In these studies, the change of the molecular weight of HA or a related parameter, such as HA solution viscosity, has been used as a marker of inflicted damage. The aim of the presented review is to briefly summarize the available data. Their correct interpretation could contribute to the implementation of modern methods of evaluation of the antioxidative capacity of natural and synthetic substances and prospective drugs--potential inflammatory disease modifying agents. Another focus of this review is to evaluate briefly the impact of different available analytical techniques currently used to investigate the structure of native high-molecular-weight hyaluronan and/or of its fragments.

Detection of individual phospholipids in lipid mixtures by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: phosphatidylcholine prevents the detection of further species

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is an established tool for the analysis of proteins, whereas it gained by far less interest in the field of lipid analysis. This method works well with phospholipids as well as organic cell extracts and provides high sensitivity and reproducibility. The aim of the present paper is to extend our previous studies to the analysis of lysophospholipids and phospholipid mixtures. To study the suitability of MALDI-TOF mass spectrometry for the analysis of lysophospholipids, different phospholipids like phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, and phosphatidylinositol as well as their mixtures were digested with phospholipase A(2). Positive and negative ion mass spectra of all phospholipids before and after digestion were recorded. In all these cases, the molecular ions of the expected digestion products could be detected and only a very small extent of further fragmentation was observed. On the other hand, spectra of phospholipid mixtures containing phosphatidylcholine were strongly dominated by phosphatidylcholine and lysophosphatidylcholine signals, which prevented the detection of further phospholipids even if those lipids were present in comparable amounts. This is of paramount interest for the analysis of tissue and cell extracts.

Lipid analysis by matrix-assisted laser desorption and ionization mass spectrometry: A methodological approach

Whereas matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has gained high importance in the field of protein analysis, surprisingly few studies were published about the use of MALDI for lipid analysis. Lipids, however, are well-suited for MALDI since all experiments can be performed in a sole organic phase and, thus, extremely homogeneous matrix/analyte mixtures are formed. We report here for the first time the application of MALDI-TOF-MS for the analysis of diacylglycerols, phosphatidylcholines, and (poly)phosphoinositides. It is shown that in a matrix of 2,5-dihydroxybenzoic acid the molecular ions (M + 1) of phosphatidylcholines as well as the corresponding adducts of different phosphoinositides are easily detected even in complex mixtures, and thus, detailed data on the fatty acid composition are provided. In contrast, diacylglycerols are mainly detected as the corresponding sodium or potassium adducts, but not as the protonated forms. Fragmentation reactions of fatty acids on the double bonds and on the polar lipid head group are observed to a minor extent in the spectra of all investigated lipids. Generally, choline derivatives are most sensitive toward further fragmentation reactions. Due to its very high sensitivity (up to picomolar concentrations) MALDI-TOF-MS can be used for the direct investigation of biologically relevant lipid mixtures occurring, e.g. , in cell membranes. The analysis of the lipid composition of neutrophilic granulocytes is given as a representative example for future applications.

Colonoscopic polypectomy in chronic colitis: conservative management after endoscopic resection of dysplastic polyps

BACKGROUND & AIMS

Adenomatous polyps are by definition dysplastic and pathologically indistinguishable from the dysplasia-associated lesion or mass (DALM) described in 1981. Yet, adenomatous polyps in noncolitic colons are usually removed definitively endoscopically, whereas DALMs are regarded as harbingers of colon cancer, mandating colectomy.

METHODS

Since 1988, all of our patients with chronic ulcerative or Crohn's colitis and dysplastic polyps and no coexistent dysplasia in flat mucosa underwent colonoscopic polypectomy. Biopsy specimens were obtained also adjacent to polypectomy sites, from strictures, and throughout the colon at 10-cm intervals. Follow-up colonoscopies and biopsies were performed within 6 months after polypectomy and yearly thereafter.

RESULTS

Colonoscopy in 48 patients with chronic colitis (mean duration, 25.4 years) resected 70 polyps (60 in colitic and 10 in noncolitic mucosa). Polyps were detected on screening colonoscopies (29%) and on surveillance (71%). Pathology was tubular adenoma in all polyps from noncolitic mucosa and low-grade dysplasia (57), high-grade dysplasia (2), or carcinoma (1) in polyps from colitic mucosa. Subsequent colonoscopies (mean follow-up, 4.1 years) revealed additional polyps in 48% but no carcinomas. Surgical resection (6 patients) for recurrent polyps confirmed colonoscopic findings. No dysplasia or cancers in flat mucosa were found at surgery or on follow-up colonoscopies.

CONCLUSIONS

In patients with chronic colitis who have no dysplasia in flat mucosa, colonoscopic resection of dysplastic polyps can be performed effectively, just as in noncolitic colons.

Outcome of patients with a performance status of 2 in Eastern Cooperative Oncology Group Study E1594: a Phase II trial in patients with metastatic nonsmall cell lung carcinoma

BACKGROUND

Eastern Cooperative Oncology Group (ECOG) Study E1594 compared paclitaxel and cisplatin with three newer chemotherapy doublets in the treatment of patients with advanced nonsmall cell lung carcinoma (NSCLC). The accrual of patients with an ECOG performance status (PS) of 2 was discontinued due to a perceived rate of unacceptable toxicity.

METHODS

Patients were stratified by PS and randomized to one of the following treatments: 1) paclitaxel (135 mg/m2) over 24 hours with cisplatin (75 mg/m2) on a 21-day cycle; 2) cisplatin (100 mg/m2) with gemcitabine (1 g/m2) on Days 1, 8, and 15 on a 28-day cycle; 3) cisplatin (75 mg/m2) with docetaxel (75 mg/m2) on a 21-day cycle; and 4) paclitaxel (225 mg/m2) over 3 hours with carboplatin (area under the curve, 6). All tests of statistical significance were two-sided.

RESULTS

Sixty-eight patients with an ECOG PS of 2 were enrolled, and 64 patients were evaluable for toxicity and response. Fifty-six percent of 64 evaluable patients were male, and 81% had Stage IV disease. Grade 3-4 hematologic toxicities occurred in > 50% of the patients in each treatment group. Nonhematologic Grade 3-4 toxicities occurred significantly less often in the paclitaxel and carboplatin arm (P = 0.0032). The overall rate of toxicity did not differ significantly from the rate of toxicity in the PS-0 or PS-1 cohorts. There were 5 deaths (7.35%) among 68 patients with a PS of 2 during therapy; however, only 2 of those deaths were attributed to therapy. The overall response rate for the 64 evaluable patients was 14%. The overall median survival of all 68 patients with a PS of 2, as determined by an intent-to-treat analysis, was 4.1 months.

CONCLUSIONS

Patients with advanced NSCLC and a PS of 2 experienced a large number of adverse reactions and overall poor survival. A comparison with patients with a PS of 0-1 suggests that these events and the shorter survival were related to disease process rather than treatment. Alternative strategies need to be explored with therapy specifically tailored for this group of patients.

Spatial profile of dendritic calcium transients evoked by action potentials in rat neocortical pyramidal neurones

1. Simultaneous measurements of intracellular free calcium concentration ([Ca2+]i) and intrasomatic and intradendritic membrane potential (Vm) were performed using fura-2 fluorimetry and whole-cell recording in neocortical layer V pyramidal neurones in rat brain slices. 2. Back-propagating action potentials (APs) evoked [Ca2+]i transients in the entire neurone including the soma, the axon initial segment, the apical dendrite up to the distal tuft branches, and the oblique and basal dendrites, indicating that following suprathreshold activation the entire dendritic tree is depolarized sufficiently to open voltage-dependent calcium channels (VDCCs). 3. The [Ca2+]i transient peak evoked by APs showed large differences between various compartments of the neurone. Following a single AP, up to 6-fold differences were measured, ranging from 43 +/- 14 nM in the soma to 267 +/- 109 nM in the basal dendrites. 4. Along the main apical dendrite, the [Ca2+]i transients evoked by single APs or trains of APs had the largest amplitude and the fastest decay in the proximal region; the [Ca2+]i transient peak and decay time constant following a single AP were 128 +/- 25 nM and 420 +/- 150 ms, respectively, and following a train of five APs (at 10-12 Hz), 710 +/- 214 nM and 390 +/- 150 ms, respectively. The [Ca2+]i transients gradually decreased in amplitude and broadened in more distal portions of the apical dendrite up to the main bifurcation. 5. In the apical tuft branches, the profile of the [Ca2+]i transients was dependent on AP frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

NMDA receptors amplify calcium influx into dendritic spines during associative pre- and postsynaptic activation

Long-term potentiation (LTP) of synaptic strength can be induced by synchronous pre- and postsynaptic activation, and a rise in postsynaptic calcium is essential for induction of LTP. Calcium can enter through both voltage-dependent Ca2+ channels and NMDA-type glutamate receptors, but the relative contributions of these pathways is not known. We have examined this issue in layer V cortical pyramidal neurons, using focal flash photolysis of caged glutamate to mimic synaptic input and two-photon, laser-scanning microscopy to measure calcium levels in dendritic spines. Most of the calcium entry in response to glutamate alone was via voltage-dependent Ca2+ channels, and NMDA receptors accounted for less than 20% of total Ca2+ entry. When glutamate was paired with postsynaptic action potentials, however, the NMDA-receptor-dependent component was selectively amplified. The same is likely to occur during paired physiological pre- and postsynaptic activation, providing a mechanism for the input specificity and Hebbian behavior of LTP.

Nasal immunization of mice with human papillomavirus type 16 virus-like particles elicits neutralizing antibodies in mucosal secretions

To specifically induce a mucosal antibody response to purified human papillomavirus type 16 (HPV16) virus-like particles (VLP), we immunized female BALB/c mice orally, intranasally, and/or parenterally and evaluated cholera toxin (CT) as a mucosal adjuvant. Anti-HPV16 VLP immunoglobulin G (IgG) and IgA titers in serum, saliva, and genital secretions were measured by enzyme-linked immunosorbent assay (ELISA). Systemic immunizations alone induced HPV16 VLP-specific IgG in serum and, to a lesser extent, in genital secretions but no secretory IgA. Oral immunization, even in the presence of CT, was inefficient. However, three nasal immunizations with 5 microgram of VLP given at weekly intervals to anesthetized mice induced high (>10(4)) and long-lasting (>15 weeks) titers of anti-HPV16 VLP antibodies in all samples, including IgA and IgG in saliva and genital secretions. CT enhanced the VLP-specific antibody response 10-fold in serum and to a lesser extent in saliva and genital secretions. Nasal immunization of conscious mice compared to anesthetized mice was inefficient and correlated with the absence of uptake of a marker into the lung. However, a 1-microgram VLP systemic priming followed by two 5-microgram VLP intranasal boosts in conscious mice induced both HPV16 VLP-specific IgG and IgA in secretions, although the titers were lower than in anesthetized mice given three intranasal immunizations. Antibodies in serum, saliva, and genital secretions of immunized mice were strongly neutralizing in vitro (50% neutralization with ELISA titers of 65 to 125). The mucosal and systemic/mucosal HPV16 VLP immunization protocols that induced significant titers of neutralizing IgG and secretory IgA in mucosal secretions in mice may be relevant to genital HPV VLP-based human vaccine trials.

Lipid analysis of human spermatozoa and seminal plasma by MALDI-TOF mass spectrometry and NMR spectroscopy - effects of freezing and thawing

In the present study, the applicability of proton NMR spectroscopy and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) to the analysis of the lipid composition of human spermatozoa and seminal fluids as well as changes after cryopreservation of human spermatozoa was investigated. Whereas NMR spectra primarily indicated a high content of double bonds within the spermatozoa but no marked differences upon cryopreservation, MS detected intense peaks which could be assigned to phosphatidylcholines containing one docosahexaenoic and one palmitic or stearic acid residue (m/z=806 and 834). In contrast, the seminal plasma contained more saturated fatty acids and especially more sphingomyelin (SM). A freezing/thawing cycle markedly influences the lipid composition of spermatozoa. There was a diminution of phosphatidylcholines (16:0, 22:6 and 18:0, 22:6) and SM (16:0) and the appearance of lysophosphatidylcholines (16:0 and 18:0) and ceramide (16:0). These data demonstrate the release or activation of both phospholipase A(2) and sphingomyelinase in human spermatozoa due to the freezing/thawing cycle. These results were finally confirmed by experiments on the action of phospholipases on lipids containing docosahexaenoic acid.

NMDA receptor-mediated dendritic spikes and coincident signal amplification

Dendrites of cortical neurons possess active conductances, which contribute to the nonlinear processing of synaptic information. Recently it has been shown that basal dendrites can generate highly localized spikes mediated by NMDA receptor channels. These spikes may serve as a powerful mechanism to detect and amplify synchronously activated spatially clustered excitatory synaptic inputs in individual dendritic segments, and may enable parallel processing in several integrative dendritic subunits.

Stability over time of serum antibody levels to human papillomavirus type 16

The stability over time of serum IgG antibody levels to human papillomavirus type 16 (HPV-16) was determined by comparing the HPV-16 capsid antibody levels in serial serum samples of an age-stratified random subsample of 1656 primiparous mothers resident in Helsinki who were followed until their second pregnancy, on average 29.5 months later. The correlation between the first and second pregnancy HPV-16 serum antibody levels of the same woman was high, even when >4 years had elapsed between pregnancies (r = .822). Between negativity, indeterminate results, or quartiles of positivity, the predictive values for being classified in the same category on both occasions ranged between 42% and 91%. Correlation coefficients, predictive values, and kappa coefficients between serial samples all were comparable with those of repeat analyses of the same sample, indicating that HPV capsid antibody levels are generally stable during several years of follow-up.

Hydration of polymeric components of cartilage--an infrared spectroscopic study on hyaluronic acid and chondroitin sulfate

Hydrated polysaccharides are major constituents of cartilage and play an important role in its water-binding properties. Infrared (IR) spectroscopy and sorption isotherms have been used to investigate the hydration behavior of the glycosaminoglycans hyaluronic acid and chondroitin sulfate. IR-dichroism of the vibrational modes of the pyranose ring is found at relative humidities (RH) smaller than 84%. The IR-dichroism data for the vibrational modes of the pyranose ring have been analyzed with respect to the helical structure of these polysaccharides. The orientation vanishes at higher relative humidities (>84%), because a strong increase in the water uptake occurs in the observed sorption isotherms. Differences in the IR-absorbance of the O-H stretching mode of sorbed water between hyaluronic acid and chondroitin sulfate are shown to be caused by the additional hydration of the sulfate groups. The corresponding H-bonds are weaker than those of the hydration shell of the pyranose rings.

Contribution of reactive oxygen species to cartilage degradation in rheumatic diseases: molecular pathways, diagnosis and potential therapeutic strategies

Inflammatory joint diseases are of considerable socio-economic significance. However, mechanisms of cartilage destruction are so far only poorly understood. This review is dedicated to reactive oxygen species (ROS) like superoxide anion radicals, hydrogen peroxide, singlet oxygen, hypochlorous acid, hydroxyl radicals and nitric oxide that are generated under inflammatory conditions and also to their potential contribution to cartilage degradation. First, the relevance of rheumatic diseases and potential mechanisms of cartilage degradation are discussed in this review, followed by the description of the chemical constituents and the molecular architecture of articular cartilage as well as the different cell types that play a role in inflammation and cartilage destruction. Methods of the assessment of cartilage degeneration are also shortly discussed. In the main chapter of this review the characteristics of individual ROS, their generation under in vivo conditions as well as their reactivities with individual cartilage components are discussed. Because of the low selectivity of ROS, useful "markers" of cartilage degradation allowing the differentiation of effects induced by individual ROS are also discussed. In the last chapter current therapeutic concepts of the treatment of rheumatic diseases are reviewed. The recently developed "anti-TNF-alpha" therapy that is primarily directed against neutrophilic granulocytes that are powerful sources of ROS and, therefore, important mediators of joint degeneration are emphasised.

Effects of hypochlorous acid on unsaturated phosphatidylcholines

Effects of hypochlorous acid and of the myeloperoxidase-hydrogen peroxide-chloride system on mono- and polyunsaturated phosphatidylcholines were analyzed by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Chlorohydrins and glycols were detected as main products according to the characteristic shift of molecular masses. Mainly mono-chlorohydrins result upon the incubation of HOCl/(-)OCl with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, whereas only traces of mono-glycols were detected. 1-Palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine yielded a complex mixture of products. Mono-chlorohydrins and glycols dominated only at short incubation, while bis-chlorohydrins as well as products containing one chlorohydrin and one glycol moiety appeared after longer incubation. Similarly, a complex product mixture resulted upon incubation of 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine with hypochlorous acid. Additionally, tris-chlorohydrins, products with two chlorohydrin and one glycol moiety, as well as lysophosphatidylcholines and fragmentation products of the arachidonoyl side chain were detectable. Mono-chlorohydrins of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine were detected after the incubation of the latter phospholipid with the myeloperoxidase-hydrogen peroxide-chloride system at pH 6.0. These chlorohydrins were not observed in the absence of chloride, hydrogen peroxide, or myeloperoxidase as well as in the presence of methionine, taurine, or sodium azide. Thus, mono-chlorohydrins in 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine produced by hypochlorous acid from the myeloperoxidase-hydrogen peroxide-chloride system can also be detected by means of MALDI-TOF MS.

Sero-epidemiological association between human-papillomavirus infection and risk of prostate cancer

Some epidemiological studies of prostate cancer have suggested the existence of a sexually transmitted risk factor, and some studies have reported the presence of human papillomavirus (HPV) DNA in prostate-cancer tissue. To perform a sero-epidemiological evaluation of whether HPV infection is associated with increased risk for prostate cancer, we performed a nested case-control study within a serum bank containing samples from 20,243 healthy Finnish men. We identified 165 cases of prostate cancer that were diagnosed up to 24 years after donation of the serum sample. Two control subjects per case were selected, matched for gender, age and municipality of residence. Serum samples were analyzed for the presence of IgG antibodies against 4 HPV types and against Chlamydia. The presence of antibodies against HPV type 18 was associated with a 2.6-fold increased risk of developing prostate cancer during follow-up (p < 0.005). HPV type 16 tended to be associated with subsequent prostate-cancer occurrence (relative risk: 2.4, p = 0.06), whereas seropositivity for HPV type 11 or type 33 or for Chlamydia was not associated with risk. The results suggest that infection with oncogenic HPV might be involved in the etiology of a minority of prostate cancers.

Sexual behaviour and papillomavirus exposure in cervical intraepithelial neoplasia: a population-based case-control study

Sexual history is an established risk determinant for cervical neoplasia. It is not clear if human papillomavirus (HPV) exposure entirely explains the sexual behaviour-related risk or if other sexually transmitted agents may act as cofactors for HPV in carcinogenesis. The aim of this study was to elucidate whether HPV exposure or HPV persistence explains the sexual history-related risk of high-grade cervical intraepithelial neoplasia (CIN) using a population-based case-control study of most of the 254 women referred to colposcopy in the Vasterbotten county in Sweden because of an abnormal cervical smear during October 1993 to December 1995 and 320 age-matched women from the general population. The women were interviewed for sexual history and tested for presence of serum antibodies to HPV-16, -18 and -33 as well as for presence of HPV DNA in cervical brush samples. HPV-16, -18 and -33 seropositivity was specific for the corresponding type of HPV DNA, dependent on the lifetime sexual history and associated with a two- to threefold increased risk of CIN 3. There was no sexual history-related risk of CIN among HPV-seropositive women and adjustment for HPV DNA presence explained the sexual history-related risk of CIN. In conclusion, HPV exposure appeared to explain the sexual history-related risk of high-grade CIN.

Limits for the detection of (poly-)phosphoinositides by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS)

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been recently established as a powerful tool for the analysis of biomolecules. Here, MALDI-TOF MS was used for the detection of (poly-)phosphoinositides (PPI). PPI possess higher molecular weights than other phospholipids and a high phosphorylation-dependent negative charge. Both features affect the MALDI detection limits expressed as the minimum of analyte on the sample plate resulting in a signal-to-noise-ratio of S/N = 5. Using 2,5-dihydroxybenzoic acid (DHB) as matrix the detection limit for phosphatidylinositol (PI) is seven times higher than for phosphatidylcholine (PC) and further increases with increasing phosphorylation or in mixtures with other well-detectable phospholipids. For phosphatidylinositol-tris-phosphate (PIP3) in a mixture with PC, the limit is about 20 times higher than for PI. The consequences for the experimental conditions are discussed. It is advisable to pre-separate PPI from biological lipid mixtures prior to the application of MALDI-TOF MS.

Formation of lysophospholipids from unsaturated phosphatidylcholines under the influence of hypochlorous acid

The formation of lysophosphatidylcholines from unsaturated phosphatidylcholines upon treatment with hypochlorous acid was evaluated by means of MALDI-TOF mass spectrometry and 31P NMR spectroscopy. With an increasing number of double bonds in a fatty acid residue, the yield of lysophosphatidylcholines with a saturated fatty acid residue increased considerably in comparison to the total amount of higher molecular weight products like chlorohydrins and glycols. High amounts of lysophosphatidylcholines were formed from phospholipids containing arachidonic or docosahexaenoic acid residues. In phospholipids with monounsaturated fatty acid residues, the position of the double bond did not influence the yield of lyso-products. Besides the exclusive formation of chlorohydrin and glycol, hypochlorous acid caused the cleavage of the unsaturated fatty acid residue independent of its location at the first or second position of the glycerol backbone. In contrast, strong alkaline conditions, i.e. saponification led also to a hydrolysis of the saturated fatty acid residue from phosphatidylcholines. It is concluded that both MALDI-TOF mass spectrometry and 31P NMR spectroscopy are able to detect the formation of lysophosphatidylcholines. We conclude also that the formation of lysophospholipids from unsaturated phosphatidylcholines by hypochlorous acid can be relevant in vivo under acute inflammatory conditions.

Comparison of development of serum antibodies to HPV16 and HPV33 and acquisition of cervical HPV DNA among sexually experienced and virginal young girls. A longitudinal cohort study

OBJECTIVES

To study the importance of sexual activity and early coitus debut on the risk for acquiring infection with human papillomavirus (HPV) type 16 or 33.

STUDY DESIGN

Ninety-eight healthy adolescent girls were followed up with consecutive interviews and donations of serum and cervical brush samples during 2 years.

RESULTS

Fourteen percent of sexually experienced girls had serum immunoglobulin G to HPV16 and/or HPV33 capsids, and 14% also had cervical HPV16 or HPV33 DNA. Seropositivity for HPV correlated with detection of cervical HPV DNA. None of the 36 girls without coital experience was seropositive or harbored cervical HPV DNA. Seropositivity for HPV was correlated strongly with the number of sexual partners: Odds ratio for > 1 sexual partner was 16.3 (P < 0.001), and for early coitus debut (younger than 17 years of age), it was 14.3 (P < 0.002).

CONCLUSIONS

Both HPV serology and HPV DNA testing indicated that the number of sexual partners and earliness of coitus debut determined the risk for acquiring HPV infection and that nonsexually transmitted infections are rare or nonexistent among adolescent girls.

Mucosal but not parenteral immunization with purified human papillomavirus type 16 virus-like particles induces neutralizing titers of antibodies throughout the estrous cycle of mice

We have recently shown that nasal immunization of anesthetized mice with human papillomavirus type 16 (HPV16) virus-like particles (VLPs) is highly effective at inducing both neutralizing immunoglobulin A (IgA) and IgG in genital secretions, while parenteral immunization induced only neutralizing IgG. Our data also demonstrated that both isotypes are similarly neutralizing according to an in vitro pseudotyped neutralization assay. However, it is known that various amounts of IgA and IgG are produced in genital secretions along the estrous cycle. Therefore, we have investigated how this variation influences the amount of HPV16 neutralizing antibodies induced after immunization with VLPs. We have compared parenteral and nasal protocols of vaccination with daily samplings of genital secretions of mice. Enzyme-linked immunosorbent assay analysis showed that total IgA and IgG inversely varied along the estrous cycle, with the largest amounts of IgA in proestrus-estrus and the largest amount of IgG in diestrus. This resulted in HPV16 neutralizing titers of IgG only being achieved during diestrus upon parenteral immunization. In contrast, nasal vaccination induced neutralizing titers of IgA plus IgG throughout the estrous cycle, as confirmed by in vitro pseudotyped neutralization assays. Our data suggest that mucosal immunization might be more efficient than parenteral immunization at inducing continuous protection of the female genital tract.