Spatial-temporal analysis of hospitalizations with death caused by oral cancer in Brazil and its correlation with the expansion of healthcare coverage.

BACKGROUND: Oral cancer (OC) is a growing public health problem worldwide. In Brazil, the National Oral Health Policy, implemented in 2004, expanded access to oral health services and prioritized OC care. However, it is not known whether this expansion resulted in a reduction in hospital admissions with death. This study aimed to analyze the proportion of hospital admissions who progressed to death due to OC in Brazil from 2007 to 2019 and its correlation with the coverage of health services. MATERIAL AND METHODS: This study is an ecological, longitudinal, and analytical study of hospital admissions with death due to OC recorded in the Brazilian Hospital Information System. The following analyses were performed: descriptive, spatial (choropleth maps and Moran index), and negative binomial regression, with a hierarchical approach, estimating crude and adjusted regression coefficients (ß) and respective 95% confidence intervals (95% CI) (alpha=5%). RESULTS: In 2019, Moran's index (I) of spatial autocorrelation showed a negative association between hospital admissions with death and dentist surgeon/inhabitant rate (I=-0.176), physician/inhabitant rate (I=-0.157), family health strategy (FHS) coverage (I=-0.080), oral health team (OHT) coverage (I= -0.129), dental specialty centers (DSC)/inhabitant rate (I= -0.200), and oncology bed/inhabitant rate (I= -0.101). In the adjusted regression analysis, the proportion of hospitalizations with deaths caused by OC was higher in Brazilian states with a lower medical ̸inhabitant ratio (ß= -0.014; p=0.040), a lower dentists/inhabitant ratio (ß= -0.720; p=0.045), a lower number of DSC (ß= -0.004; p<0.000), a lower amount paid per hospitalization (ß= -10.350; p<0.001), and a lower number of biopsies (ß= -0.00008; p=0.010). The proportion of hospitalizations that progressed to death showed a positive association with the number of days of hospitalization (ß= 0.00002; p=0.002). CONCLUSIONS: Increased health care coverage has decreased serious hospital admissions with deaths caused by OC in Brazil.

Socioeconomic inequalities and temporomandibular joint disorders in adolescents: contributions from a Maranhão cohort.

AIM: To assess the prevalence of temporomandibular disorder (TMD) in adolescents and estimate possible associations with poverty. BASIC RESEARCH DESIGN: A cross-sectional study nested within a prospective birth cohort study conducted in São Luís, Maranhão, Brazil. PARTICIPANTS: 2,412 adolescents aged 18-19 years. MATERIAL AND METHODS: The presence of TMD, classified according to the Fonseca Anamnestic Index, was used as the outcome. The following explanatory variables were assessed: gender, household head, paved/asphalted street, piped water, and socioeconomic background, based on the Brazilian Association of Market Research criteria and the poverty income ratio (PIR). Logistic regression analysis was performed with the estimation of odds ratios (OR) and 95% confidence intervals. RESULTS: TMD was common (51.4%) and was associated with poverty, as it was more frequent among adolescents from social classes D-E (OR=2.60; 95% CI: 1.48-4.55) and C (OR=1.82; 95% CI: 1.12-2.99) compared to A/B, and among poor adolescents using the PIR (OR=1.50; 95% CI: 1.02-2.33). CONCLUSIONS: The prevalence of TMD in socioeconomically disadvantaged adolescents in São Luís is high, and these data allow the early identification of at-risk groups. We recommend carrying out other population-based studies, using diagnostic strategies with greater accuracy.

Identification of the first homozygous 1-bp deletion in GDF9 gene leading to primary ovarian insufficiency by using targeted massively parallel sequencing.

Targeted massively parallel sequencing (TMPS) has been used in genetic diagnosis for Mendelian disorders. In the past few years, the TMPS has identified new and already described genes associated with primary ovarian insufficiency (POI) phenotype. Here, we performed a targeted gene sequencing to find a genetic diagnosis in idiopathic cases of Brazilian POI cohort. A custom SureSelectXT DNA target enrichment panel was designed and the sequencing was performed on Illumina NextSeq sequencer. We identified 1 homozygous 1-bp deletion variant (c.783delC) in the GDF9 gene in 1 patient with POI. The variant was confirmed and segregated using Sanger sequencing. The c.783delC GDF9 variant changed an amino acid creating a premature termination codon (p.Ser262Hisfs*2). This variant was not present in all public databases (ExAC/gnomAD, NHLBI/EVS and 1000Genomes). Moreover, it was absent in 400 alleles from fertile Brazilian women screened by Sanger sequencing. The patient's mother and her unaffected sister carried the c.783delC variant in a heterozygous state, as expected for an autosomal recessive inheritance. Here, the TMPS identified the first homozygous 1-bp deletion variant in GDF9. This finding reveals a novel inheritance pattern of pathogenic variant in GDF9 associated with POI, thus improving the genetic diagnosis of this disorder.

Malignant testicular germ cell tumors in postpubertal individuals with androgen insensitivity: prevalence, pathology and relevance of single nucleotide polymorphism-based susceptibility profiling.

STUDY QUESTION: What is the prevalence of malignant testicular germ cell tumors (TGCT) and its precursors, (pre-) germ cell neoplasia in situ (GCNIS), in late teenagers and adults who have androgen insensitivity syndrome (AIS) and the impact of an individual's genetic susceptibility to development of TGCT? SUMMARY ANSWER: No GCNIS or TGCT was diagnosed, but pre-GCNIS was identified in 14 and 10% of complete and partial AIS patients, respectively, and was associated with a higher genetic susceptibility score (GSS), with special attention for KITLG (rs995030) and ATFZIP (rs2900333). WHAT IS KNOWN ALREADY: Many adult women with AIS decline prophylactic gonadectomy, while data regarding the incidence, pathophysiology and outcomes of TGCT in postpubertal individuals with AIS are lacking. The relevance of genetic factors, such as single nucleotide polymorphisms (SNPs), in predisposing AIS individuals to TGCT is unknown. STUDY DESIGN, SIZE, DURATION: This multicenter collaborative study on prophylactically removed gonadal tissue was conducted in a pathology lab specialized in germ cell tumor biology. PARTICIPANTS/MATERIALS, SETTING, METHODS: Material from 52 postpubertal individuals with molecularly confirmed AIS (97 gonadal samples) was included; the median age at surgery was 17.5 (14-54) years. Immunohistochemical studies and high-throughput profiling of 14 TGCT-associated SNPs were performed. The main outcome measures were the prevalence of pre-GCNIS, GCNIS and TGCT, and its correlation with a GSS, developed based on the results of recent genome-wide association studies. MAIN RESULTS AND ROLE OF CHANCE: The earliest recognizable change preceding GCNIS, referred to as pre-GCNIS, was present in 14% of individuals with complete and 10% of those with partial AIS at a median age of 16 years. No GCNIS or invasive TGCT were found. The median GSS was significantly greater for those with, compared to those without, pre-GCNIS (P = 0.01), with an overlap between groups. Our data suggest important roles for risk alleles G at KITLG (rs995030) and C at ATFZIP (rs2900333), among the 14 studied TGCT-associated SNPs. LARGE SCALE DATA: N/A. LIMITATIONS REASONS FOR CAUTION: A limited number of cases were included. WIDER IMPLICATIONS OF THE FINDINGS: Our data suggest that the prevalence of pre-GCNIS in individuals with AIS beyond puberty is around 15%. Genetic susceptibility likely contributes to pre-GCNIS development in AIS but factors related to malignant progression remain unclear. Although data in older patients remain scarce, malignant progression appears to be a rare event, although the natural history of the premalignant lesion remains unknown. Therefore, the practice of routine prophylactic gonadectomy in adults with AIS appears questionable and the patient's preference, after having been fully informed, should be decisive in this matter. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by research grants from the Research Foundation Flanders (FWO) (to M.C.), the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq G0D6713N) (to B.B.M. and M.C.) and the European Society for Pediatric Endocrinology (ESPE), granted by Novo Nordisk AB (to J.K.). There are no competing interests.

Anthocyanin extraction from plant tissues: A review.

Anthocyanins have gathered the attention of the scientific community mostly due to their vast range of possible applications. They have been the center point of the research in many different fields, among which is food development, where their innate coloring, antioxidant capacity, and biological potential open interesting venues to the development of new food additives and functional foodstuffs. As the range of application grows, so does the necessity to obtain these compounds, and since they are naturally occurring, the most common way to obtain anthocyanins is to extract them from different plant sources, such as fruits and flowers. Several efforts have been made to develop methods that allow for better extraction yields and higher purification rates therefore this review aims to compile the information regarding extraction and purification procedures in a comprehensive manner.

Insights into chitosan antibiofilm activity against methicillin-resistant Staphylococcus aureus.

AIMS: Chitosan is a natural compound that has been validated as a viable antimicrobial agent against Staphylococcus aureus. With this work we sought to evaluate the planktonic and sessile sensitivity of methicillin-resistant S. aureus to chitosan's activity and evaluate if methicillin-resistant S. aureus (MRSA) would be more or less sensitive to chitosan's activity than methicillin-sensitive S. aureus (MSSA). METHODS AND RESULTS: A group comprised of reference strains and clinical multiresistant isolates of MSSA and MRSA were used. Methicilin resistance effect upon chitosan activity was assessed in planktonic setting and in different phases of sessile colonization, namely adhesion, biofilm formation and mature biofilm through biomass and metabolism inhibition. The results obtained showed that S. aureus methicillin resistance mechanism did not impair chitosan's activity as the highest bacterial susceptibility was registered for MRSA. Chitosan was highly effective in inhibiting MSSA and MRSA strains in both planktonic and sessile settings with biofilm inhibition percentages reaching as high as 90% for MRSA. CONCLUSIONS: Staphylococcus aureus methicillin resistance did not impair chitosan's antimicrobial and antibiofilm activities and MRSA and MSSA were inhibited both in planktonic and sessile settings at low concentrations with great efficacy. SIGNIFICANCE AND IMPACT OF THE STUDY: Considering the obtained results chitosan shows potential as an alternative for the control of biofilm-related recalcitrant MRSA infections.

Antimicrobial, antiadhesive and antibiofilm activity of an ethanolic, anthocyanin-rich blueberry extract purified by solid phase extraction.

AIMS: The present work aimed to characterize the impact of an anthocyanin-rich blueberry extract upon the growth, adhesion and biofilm formation of several pathogens including some multiresistant bacteria. METHODS AND RESULTS: A group comprised of reference strains and clinical multiresistant isolates of Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Acinetobacter baumannii and Staphylococcus aureus, were used to screen for antimicrobial activity. Microbial growth was determined through the measurement of the optical density while adhesion and biofilm formation was determined using the standard crystal violet staining procedure. The results showed that, while blueberry extract was only effective in hindering the growth of Staph. aureus and E. coli, it was capable of significantly inhibiting biofilm formation and bacterial adhesion for all micro-organisms tested. CONCLUSIONS: The extract demonstrated a considerable potential as a natural, alternative antimicrobial capable of either interfering with microbial growth or hamper the adhesion to surfaces, with Staph. aureus proving to be the most susceptible micro-organism. SIGNIFICANCE AND IMPACT OF THE STUDY: The overall study demonstrates the potential of anthocyanin extracts as natural effective alternative antimicrobial agents. Additionally, the extract's capacity to reduce adhesion without reducing bacterial growth reduces the likeliness of resistance development while reducing the probability of infection.

Diagnosis of prolactinoma in two male-to-female transsexual subjects following high-dose cross-sex hormone therapy.

Male-to-female transsexual persons use oestrogens + antiandrogens to adapt their physical bodies to the female sex. Doses are usually somewhat higher than those used by hypogonadal women receiving oestrogen replacement. Particularly in cases of self-administration of cross-sex hormones, doses may be very high. Oestrogens are powerful stimulators of synthesis and release of prolactin and serum prolactin levels are usually somewhat increased following oestrogen treatment. Prolactinomas have been reported in male-to-female transsexual persons, both after use of high and conventional doses of oestrogens but remain rare events. We report two new cases of prolactinomas in male-to-female transsexual persons, one in a 41-year-old subject who had used nonsupervised high-dose oestrogen treatment since the age of 23 years and another one in a 42 year old who had initiated oestrogen treatment at the age of 17 years. Their serum prolactin levels were strongly increased, and the diagnosis of a pituitary tumour was confirmed by imaging techniques. Both cases responded well to treatment with cabergoline treatment whereupon serum prolactin normalised. Our two cases are added to the three cases of prolactinomas in the literature in persons who had used supraphysiological doses of oestrogens.

Association between oral conditions and functional limitations in childhood.

The aim of this study was to evaluate the impact of oral conditions on functional limitations among preschoolers. A preschool-based, cross-sectional study was carried out with 843 preschoolers in Campina Grande, Brazil. Parents/caregivers answered a questionnaire addressing socio-demographic characteristics and perceptions regarding the general/oral health of their children as well as the Brazilian version of the Early Childhood Oral Health Impact Scale. The nonparametric Kruskal-Wallis test followed by Mann-Whitney test (α = 5%) was used to compare mean children's quality-of-life scores for each independent variable. Poisson regression analysis was used to test associations between the independent and dependent variables (difficulties eating, drinking and speaking) (α = 5%). The multivariate regression model involved a hierarchical approach with four levels (distal to proximal determinants): (i) socio-demographic aspects; (ii) health perceptions; (iii) oral conditions; and (iv) pain conditions. The prevalence of negative impact on function was 24.7% for eating/drinking and 8.0% for speaking. Significant associations were found between toothache and negative impact on eating/drinking (PR = 5.38; 95%CI: 3.20-9.02) as well as between high severity dental caries and negative impact on speaking (PR = 14.91; 95%CI: 1.98-112.32). Dental caries, traumatic dental injury and malocclusion were not significantly associated with a negative impact on eating or drinking. However, toothache was an indicator of negative impact on eating/drinking and dental caries severity was an indicator of negative impact on speaking.

Genetic divergence among African cowpea lines based on morphoagronomic traits.

The aim of this study was to estimate the genetic divergence between African cowpea lines from the Cowpea Germplasm Bank of Embrapa Meio-Norte, Brazil. The morphoagronomic diversity of 57 cowpea lines was assessed using multivariate analysis. The germplasm was evaluated in August 2009 using a randomized block design with three replications based on the following traits: number of pods per peduncle, pod length (PL), number of grains per pod (NGP), grain length (GRL), grain width, 100-grain weight (W100G), and yield. The heritability values of the traits PL, NGP, GRL, and W100G were all higher than 70%, indicating the possibility of genetic progress with selection. The crosses between the lines IT82D-889 and IT89KD-245, IT85F-1380 and IT89KD-245, and IT89KD-245 and IT98K-1092-1 could result in promising genetic combinations. The characteristics that contributed most to genetic divergence were W100G (49.7%), PL (16.7%), GRL (12.0%), and NGP (9.7%).

Study of the effects of chitosan upon Streptococcus mutans adherence and biofilm formation.

The main aim of this work was to access the potential use of high and low molecular weight chitosans as potential oral antimicrobials, particularly as antibiofilm agents. Chitosan's interference with Streptococcus mutans capability to adhere and form biofilms was assessed. Additionally the effect upon mature and polymicrobial biofilms was also evaluated. The results obtained showed that chitosan was capable of interfering with S. mutans adhesion and primary biofilm formation. This action was observed up to a week with little to none decrease in efficiency. In addition chitosan was capable of inhibiting biofilms formed by two microorganisms and was capable of acting upon mature biofilms leading to significant reductions (94%) in biofilm survival. However clear statistical differences (p < 0.05) were registered in all assays with, in most assays, HMw chitosan presenting higher efficiency than LMw chitosan. Considering this results chitosan's potential as a valid alternative to traditional antimicrobials in oral health it's evident.

Evaluation and insights into chitosan antimicrobial activity against anaerobic oral pathogens.

The objective of this study was to assess the antimicrobial capability of non-chemically altered chitosan as an alternative to traditional antimicrobials used in the treatment of oral infections. The action mechanism of chitosan was also ascertained. High and low molecular weight chitosan showed antimicrobial activity at low concentrations for all tested bacteria with the MICs varying between 1 and 7 mg/ml with a drop of efficacy relatively to the action of LMW chitosan. In addition chitosan showed also to be an effective bactericidal presenting bactericidal effect within 8 h at the latest. Additionally the evaluation of chitosan's action mechanism showed that both MWs acted upon the bacterial cell wall and were not capable of interacting with the intracellular substances, as showed by the inefficacy obtained in the flocculation assay.

Partial VP2 sequencing of canine parvovirus (CPV) strains circulating in the state of Rio de Janeiro, Brazil: detection of the new variant CPV-2c.

Canine parvovirus (CPV) is the most important enteric virus for dogs and it seems to be undergoing continuous evolution, generating new genetic and antigenic variants throughout the world. The aim of this study was to analyze the distribution of CPV variants from 1995 to 2009 and to investigate the circulation of the new variant CPV-2c in Rio de Janeiro, Brazil. In addition, the clinical features of CPV infection were also reported. After CPV laboratorial confirmation by HA/HI and PCR, thirty-two fecal samples were analyzed by sequencing a 583-bp fragment of the VP2 gene. One sample, collected in 2008 was typed as the new type CPV-2c. All samples from 1995 to 2003 were identified as "new CPV-2a". From 2004 to 2006, both "new CPV-2a" and CPV-2b were observed. From 2006 to 2009, most of the samples were characterized as CPV-2b. The classical signs of CPV enteritis were observed in 16/18 CPV-2a and 5/13 CPV-2b infected puppies. These results show that continuous epidemiological surveillance of CPV strain distribution is essential for studying the patterns of CPV-2a and 2b spread and for determining whether the new variant CPV-2c has become permanently established in Brazilian canine population.

Children's perceptions regarding functional limitations due to oral problems.

AIM: To evaluate factors associated with difficulty eating and speaking due to oral problems according to the reports of children. METHODS: A cross-sectional study was conducted with 769 5-year-old children at preschools in a city in northeast Brazil. Parents/caretakers answered a questionnaire addressing socio-demographic data and a history of dental pain. The children answered the scale of oral health outcomes for 5-year-old children, which was used to evaluate the dependent variables. Clinical examinations of the children were performed by examiners who had undergone calibration exercises. Data analysis involved descriptive statistics and Poisson regression analysis (α = 5%). RESULTS: The prevalence of the perception of functional limitations on the part of the children was 35.5% for difficulty eating and 22.9% for difficulty speaking. Difficulty eating was associated with a history of dental pain (PR = 1.68; 95% CI 1.27-2.22) and the occurrence of traumatic dental injury (TDI) (PR = 1.23; 95% CI 1.01-1.52). Difficulty speaking due to oral problems was associated with studying at a public preschool (PR = 1.71; 95% CI 1.19-2.46), a history of dental pain (PR = 1.54; 95% CI 1.07-2.20), and the occurrence of TDI (PR = 1.52; 95% CI 1.12-2.06). CONCLUSIONS: Pain symptoms and the occurrence of TDI can exert an influence on the development of functional limitations. With regard to socioeconomic factors, studying at a public preschool can influence difficulty speaking in children.

Assessment of markers of bone formation under controlled environmental factors and their correlation with serum minerals in adult sheep as a model for orthopaedic research.

Eighteen healthy skeletally mature (3 years old) ewes, with an average weight of 45 kg, of the Portuguese Churra da Terra Quente breed were used to evaluate the normal values of total and bone-specific isoform of alkaline phosphatase serum activities (ALP and BALP, respectively) and serum osteocalcin (OC) and their correlation with the serum minerals - calcium (Ca), phosphorus (P), magnesium (Mg) and ionized calcium (Ca(2+)). The sheep were maintained under controlled environmental conditions (constant diurnal photoperiod cycle and identical husbandry and feeding) for six weeks before the collection of the blood samples. The measurement of the total ALP and serum minerals was performed with automated biochemistry analysers using the BioMérieux kits, the serum electrolyte Ca(2+) Diametrics Medical, Inc specific cassettes and the BALP and OC METRATM kits from QUIDEL Corporation. The mean +/- standard deviation values obtained were: total ALP 90.17 +/- 85.72 U/L, BALP 15.0 +/- 5.44 U/L, ratio BALP/ total ALP 29.28 +/- 24.22, OC 13.02 +/- 1.87 ng/mL, Ca 2.57 +/- 0.37 mmol/L, P 2.13 +/- 0.42 mmol/L, Mg 1.04 +/- 0.13 mmol/L, Ca(2+) 1.29 +/- 0.04 mmol/L. Significant correlations were observed between the total ALP and Ca (r = 0.5939; P = 0.05) and OC and Ca (r = 0.5706; P = 0.05). Reference to the serum values of bone turnover parameters in sheep could be of great value in research and could provide complementary non-invasive information on the bone healing process, particularly with regard to obtaining an early prognosis of fracture healing.

Impact of endostatin gene therapy on myeloid-derived suppressor cells from a metastatic renal cell carcinoma.

AIM: To evaluate the role of endostatin (ES) gene therapy on myeloid-derived suppressor cells (MDSC) in a metastatic model of renal cell carcinoma (RCC). MATERIALS AND METHODS: Balb/C mice bearing orthotopic Renca tumors were treated with NIH/3T3-LendSN or, as a control, with NIH/3T3-LXSN cells. At the end of in vivo experiment, plasma and tissue lung samples were collected. Plasma ES and granulocyte colony stimulating factor (G-CSF) levels were measured by ELISA and Milliplex, respectively. Quantification of CD11b+Gr-1+ cells and their subsets was performed by flow cytometry. Reactive oxygen species (ROS) production was measured in CD11b+Gr-1+ MDSC using the DCFDA marker by flow cytometry. RESULTS: Metastatic RCC (mRCC) induced expansions of CD11b+Gr-1+ MDSC and promoted accumulation of these cells and their subtypes in lymphoid organ and metastases. ES treatment promoted low G-CSF plasmatic levels which were produced by the tumor microenvironment, reflecting the reduced metastatic accumulation of CD11b+Gr-1+ MDSC in the lungs. However, the therapy was selective for granulocytic cells, thus reducing the production of ROS. CONCLUSION: These findings confirm the expansion of MDSC during metastatic progression of RCC and indicate the important role of ES in reducing MDSC and possible use of ES therapy in combined anticancer treatment.

Oral phaeohyphomycosis.

This is the first description of solitary phaeohyphomycosis affecting the mucosal surface. The lesion developed in the inferior lip of a 57-year-old woman. After surgical resection, histopathological examination evidenced characteristic brownish fungal structures within granulomatous-purulent inflammation. Amplification and sequencing of rDNA obtained from paraffin-embedded tissue identified Alternaria species, as the causative agent.

Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumannii.

Over the last two decades worldwide levels of antibiotic resistance have risen leading to the appearance of multidrug resistant microorganisms. Acinetobacter baumannii is a known skin pathogen which has emerged as a major cause of nosocomial outbreaks due to its capacity to colonize indwelling medical devices and natural antibiotic resistance. With chitosan being an effective antimicrobial agent against antibiotic resistant microorganisms, the aim of this work was to access its potential as an alternative to traditional antimicrobials in the management of A. baumannii growth. What the results showed was that both chitosan MW's tested were active upon A. baumannii's planktonic and sessile growth. For planktonic growth MICs and MBCs were obtained at relatively low concentrations (0.5-2mg/mL) while for sessile growth chitosan proved to be an effective inhibitor of A. baumannii's adhesion and biofilm formation. Considering these results chitosan shows a high potential for control of A. baumannii infections.

Chitosan nanoparticles as alternative anti-staphylococci agents: Bactericidal, antibiofilm and antiadhesive effects.

Chitosan is a biocompatible, bioactive, non-toxic polymer that due to these characteristics has been widely used as a carrier for targeted delivery of bioactive molecules. In recent years, and considering that chitosan has a strong antimicrobial potential, the scientific community's focus has shifted onto the possible antimicrobial activity of chitosan nanoparticles. With this in mind, the aim of this work was to produce low molecular weight chitosan nanoparticles, through the ionic gelation method and characterize their potential biological activity against three staphylococci (MSSA, MRSA and MRSE) in planktonic and sessile environments. The chitosan nanoparticles produced had an average size of 244±12nm, an average charge of 17.3±1.4mV and had a MIC of 1.25mg/mL for all tested microorganisms. Bactericidal activity was only registered for MSSA and MRSA with the time-inhibition curves showing bactericidal activity within 1h. Assays regarding chitosan nanoparticles' impact upon sessile populations showed that they were effective in preventing MRSE adhesion and highly effective in reducing MRSA and MSSA biofilm formation.

Evidence for active phospholipase A in mouse plasma.

Mouse, rat and human plasma were exposed to minimum concentrations of disulphide or minimum pre-incubation at 55 degrees C in order to inhibit lecithin : cholesterol acyltransferase activity completely. The plasma samples were subsequently incubated at 37 degrees C and changes in individual phospholipid concentrations determined. Significant utilization of phosphatidylcholine and formation of lysophosphatidylcholine occurred only in disulphide-treated mouse plasma and this was accompanied by a decrease in total phospholipid concentration. When disulphide-treated mouse plasma was incubated with [U-14C]phosphatidylcholine radioactivity was additionally recovered in the lysophosphatidylcholine, non-esterified fatty acid and glycero-3-phosphocholine fractions; maximum conversion occurred at close to physiological pH. These observations suggest that phospholipase A and lysophosphatidylcholine hydrolase enzymes are active in mouse plasma but that phospholipase A is either absent or inactive in rat and human plasma.