Rechallenge with Anti-EGFR Treatment in RAS/BRAF wt Metastatic Colorectal Cancer (mCRC) in Real Clinical Practice: Experience of the GITuD Group

BACKGROUND

There are few third- and fourth-line therapeutic options for metastatic colorectal cancer (mCRC). In RAS/BRAF wild-type (wt) mCRC previously treated with anti-epidermal growth factor receptor (anti-EGFR) (first-line) and relapsed after a good response, retreatment with anti-EGFR (rechallenge) emerges as a therapeutic alternative.

OBJECTIVE

The aim was to show the activity and safety of anti-EGFR rechallenge in RAS/BRAF wt mCRC in real-world practice.

PATIENTS AND METHODS

A multicenter, retrospective, observational study (six hospitals of the Galician Group of Research in Digestive Tumors) was conducted. Adult patients with RAS/BRAF wt mCRC, evaluated by liquid biopsy, were included. They received anti-EGFR rechallenge (cetuximab, panitumumab) as monotherapy, or combined with chemotherapy, in third- or subsequent lines. Efficacy (overall response rate [ORR], disease control rate [DCR], overall survival [OS], and progression-free survival [PFS]) and safety (incidence of adverse events [AEs]) were assessed.

RESULTS

Thirty-one patients were analyzed. Rechallenge (median 6 cycles [range 1-27], mainly cetuximab [80.7%]), started at a median anti-EGFR-free time of 18.4 months (1.7-37.5 months) after two (38.7%) or more (61.3%) lines of treatment; 64.5% of patients received a full dose. Median OS and PFS were 9.8 months (95% confidence interval [CI] 8.2-11.4) and 2.6 months (95% CI 1.7-3.4), respectively. ORR was 10%, and DCR was 30%. The most common AEs were diarrhea (35.5%), anemia (29%), emesis (6.4%), and neutropenia (6.4%); < 5% grade ≥ 3; 48.4% of patients reported anti-EGFR-related skin toxicity (grade > 1). Hypomagnesemia required supplements in 29% of patients. Dose delays (≥ 3 days) and reduction (≥ 20%) were reported in 11 (35.5%) and seven patients (22.6%), respectively.

CONCLUSIONS

In RAS/BRAF wt mCRC patients, an anti-EGFR rechallenge provides a feasible therapeutic option with clinical benefit (survival) and a manageable safety profile.

Sequential RAS mutations evaluation in cell-free DNA of patients with tissue RAS wild-type metastatic colorectal cancer: the PERSEIDA (Cohort 2) study

PURPOSE

RAS (KRAS/NRAS) mutational status on a tumor biopsy is mandatory to guide the best treatment in metastatic colorectal cancer (mCRC). Determining the RAS mutational status by tumor-tissue biopsy is essential in guiding the optimal treatment decision for mCRC. RAS mutations are negative predictive factors for the use of EGFR monoclonal antibodies. Cell-free DNA (cfDNA) analysis enables minimally invasive monitoring of tumor evolution.

METHODS/PATIENTS

PERSEIDA was an observational, prospective study assessing cfDNA RAS, BRAF and EGFR mutations (using Idylla™) in first-line mCRC, RAS wild-type (baseline tumor-tissue biopsy) patients (cohort 2). Plasma samples were collected before first-line treatment, after 20 ± 2 weeks, and at disease progression.

RESULTS

117 patients were included (103 received panitumumab + chemotherapy as first-line treatment). At baseline, 7 (6.8%) patients had RAS mutations, 4 (3.9%) BRAF mutations and no EGFR mutations were detected (cfDNA, panitumumab + chemotherapy subpopulation [panitumumab + Ch]). The baseline RAS mutational status concordance between tissue and liquid biopsies was 94.0% (93.2%, panitumumab + Ch). At 20 weeks, only one patient in the study (included in the panitumumab + Ch) had an emerging cfDNA RAS mutation. No emerging BRAF or EGFR mutations were reported. At disease progression, 6 patients had emergent mutations not present at baseline (RAS conversion rate: 13.3% [6/45]; 15.0% [6/40], panitumumab + Ch).

CONCLUSIONS

The concordance rate between liquid and solid biopsies at baseline was very high, as previously reported, while our results suggest a considerable emergence of RAS mutations during disease progression. Thus, the dynamics of the genomic landscape in ctDNA may provide relevant information for the management of mCRC patients.

Incidence, risk factors, and evolution of venous thromboembolic events in patients diagnosed with pancreatic carcinoma and treated with chemotherapy on an outpatient basis

BACKGROUND

Pancreatic carcinoma is one of the tumors associated with a higher risk for thromboembolic events, with incidence rates ranging from 5% to 41% in previous retrospective series.

PATIENTS AND METHODS

We conducted a retrospective study in eleven Spanish hospitals that included 666 patients diagnosed with pancreatic carcinoma (any stage) between 2008 and 2011 and treated with chemotherapy. The main objective was to evaluate the incidence of venous thromboembolic events (VTE) in this population, as well as potential risk factors for thrombosis. The impact of VTE on mortality was also assessed.

RESULTS

With a median follow-up of 9.3 months, the incidence of VTE was 22.1%; 52% were diagnosed incidentally. Our study was unable to confirm the ability of the Khorana score to discriminate between patients in the intermediate or high risk category for thrombosis. The presence of VTE proved to be an independent prognostic factor associated with increased risk of death (HR 2.39, 95% CI 1.96-2.92). Symptomatic events correlated with higher mortality than asymptomatic events (HR 1.72; 95% CI, 1.21-2.45; p = 0.002), but incidental VTE, including visceral vein thrombosis (VVT), negatively affected survival compared to patients without VTE. Subjects who developed VTE within the first 3 months of diagnosis of pancreatic carcinoma had lower survival rates than those with VTE after 3 months (HR 1.92, 95% CI 1.30-2.84; p&lt;0.001).

CONCLUSIONS

Pancreatic carcinoma is associated with a high incidence of VTE, which, when present, correlates with worse survival, even when thrombosis is incidental. Early onset VTE has a particularly negative impact.

FOLFOXIRI plus bevacizumab versus FOLFOX plus bevacizumab for patients with metastatic colorectal cancer and ≥3 circulating tumour cells: the randomised phase III VISNÚ-1 trial

PURPOSE

5-Fluorouracil/leucovorin, oxaliplatin, irinotecan (FOLFOXIRI) plus bevacizumab is more effective than doublets plus bevacizumab as first-line therapy for metastatic colorectal cancer, but is not widely used because of concerns about toxicity and lack of predictive biomarkers. This study was designed to explore the role of circulating tumour cell (CTC) count as a biomarker to select patients for therapy with FOLFOXIRI-bevacizumab.

PATIENTS AND METHODS

VISNÚ-1 was a multicentre, open-label, randomised, phase III study in patients with previously untreated, unresectable, metastatic colorectal carcinoma and ≥3 CTC/7.5 mL blood. Patients received bevacizumab 5 mg/kg plus FOLFOXIRI (irinotecan 165 mg/m², oxaliplatin 85 mg/m², leucovorin 400 mg/m² and 5-fluorouracil 3200 mg/m²) or FOLFOX (oxaliplatin 85 mg/m², leucovorin 400 mg/m², 5-fluorouracil 400 mg/m² then 2400 mg/m²) by intravenous administration every 2 weeks. The primary outcome was progression-free survival (PFS).

RESULTS

The intention-to-treat population comprised 349 patients (FOLFOXIRI-bevacizumab, n=172; FOLFOX-bevacizumab, n=177). Median PFS was 12.4 months (95% CI 11.2 to 14.0) with FOLFOXIRI bevacizumab and 9.3 months (95% CI 8.5 to 10.7) with FOLFOX-bevacizumab (stratified HR, 0.64; 95% CI 0.49 to 0.82; p=0.0006). Grade≥3 adverse events were more common with FOLFOXIRI-bevacizumab 85.3% vs 75.1% with FOLFOX-bevacizumab (p=0.0178). Treatment-related deaths occurred in 8 (4.7%) and 6 (3.4%) patients, respectively.

CONCLUSIONS

First-line FOLFOXIRI-bevacizumab significantly improved PFS compared with FOLFOX-bevacizumab in patients with metastatic colorectal cancer and ≥3 CTCs at baseline, which indicate a poor prognosis. CTC count may be a useful non-invasive biomarker to assist with the selection of patients for intensive first-line therapy.

Effect of antiangiogenic-based treatment and systemic inflammatory factors on outcomes in patients with BRAF v600-mutated metastatic colorectal cancer: a real-world study in Spain

Background

Outcomes are poorer in metastatic colorectal cancer (mCRC) patients with BRAF V600E mutations than those without it, but the effect of these mutations on treatment response is unclear. This real-world study assessed the effects of antiangiogenic-based treatment and systemic inflammatory factors on outcomes in patients with BRAF V600-mutated mCRC.

Methods

This real-world, multicenter, retrospective, observational study included patients with BRAF V600-mutated mCRC treated in eight hospitals in Spain. The primary endpoints were overall survival (OS) and progression-free survival (PFS); overall response rate (ORR) and disease control rate (DCR) were also assessed. The effect of first- and second-line treatment type on OS, PFS, ORR, and DCR were evaluated, plus the impact of systemic inflammatory markers on these outcomes. A systemic inflammation score (SIS) of 1–3 was assigned based on one point each for platelet-lymphocyte ratio (PLR) ≥200, neutrophil-lymphocyte ratio (NLR) ≥3, and serum albumin < 3.6 g/dL.

Results

Of 72 patients, data from 64 were analyzed. After a median of 69.1 months, median OS was 11.9 months and median first-line PFS was 4.4 months. First-line treatment was triplet chemotherapy-antiangiogenic (12.5%), doublet chemotherapy-antiangiogenic (47.2%), doublet chemotherapy-anti-EGFR (11.1%), or doublet chemotherapy (18.1%). Although first-line treatment showed no significant effect on OS, antiangiogenic-based regimens were associated with prolonged median PFS versus non-antiangiogenic regimens. Negative predictors of survival with antiangiogenic-based treatment were NLR, serum albumin, and SIS 1–3, but not PLR. Patients with SIS 1–3 showed significantly prolonged PFS with antiangiogenic-based treatment versus non-antiangiogenic-based treatment, while those with SIS=0 showed no PFS benefit.

Conclusions

Antiangiogenic-based regimens, SIS, NLR, and albumin were predictors of survival in patients with mCRC, while SIS, NLR and serum albumin may predict response to antiangiogenic-based chemotherapy.

Trial registration

GIT-BRAF-2017-01.

Sustained Stable Disease with Capecitabine plus Bevacizumab in Metastatic Appendiceal Adenocarcinoma: A Case Report

In a patient who had been diagnosed in 2006 with appendiceal adenocarcinoma with peritoneal metastases after an incomplete surgery, palliative chemotherapy was administered. First-line treatment with 5-fluorouracil, leucovorin and oxaliplatin (FOLFOX) and second-line treatment including 5-fluorouracil, leucovorin and irinotecan (FOLFIRI) plus panitumumab showed inefficiency in controlling disease progression. Third-line chemotherapy combining capecitabine plus bevacizumab was started, achieving good control of the tumour growth and a minor response in the second computed tomography scan. We decided to maintain the treatment, although forced bevacizumab “breaks” were necessary due to unexpected adverse events, with the patient suffering disease progression every time bevacizumab was stopped and reaching minor response again once the antiangiogenic treatment was reintroduced. During more than 10 years after starting third-line treatment, the patient maintained good performance status and disease stability with this “up and down” management until January 2019, when a neurological adverse event during bevacizumab infusion drove us to abandon it definitely.

Randomized phase III study comparing FOLFOX + bevacizumab versus folfoxiri + bevacizumab (BEV) as 1st line treatment in patients with metastatic colorectal cancer (mCRC) with ≥3 baseline circulating tumor cells (bCTCs)

3507

Background: FOLFOXIRI+BEV has demonstrated a survival benefit compared with FOLFIRI plus BEV (TRIBE Lancet Oncol 2015) in first-line mCRC. Nevertheless, due to its safety profile, this schedule is not recommended for all pts. In addition, we have showed that the detection of ≥3 bCTCs is a poor prognostic factor for survival (MACRO The Oncologist 2012). The VISNU-1 trial compares FOLFOX + BEV vs FOLFOXIRI + BEV in pts with mCRC and ≥3 bCTCs. Progression-free survival (PFS) is the primary endpoint. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Methods: This is an open, multicentric, randomized phase III trial. Patients with mCRC younger than 70 years, ECOG 0-1 were randomized to FOLFOX+BEV (arm A) or FOLFOXIRI+BEV (arm B), stratified per KRAS mutation (mutated vs WT) and number of involved organs (1 vs >1). Results: 349 pts were included in the ITT population; 177 in group A and 172 in group B. Characteristics of the pts, molecular profiling and safety analysis have been previously presented at ASCO 2018 and showed that this schedule had an acceptable toxicity profile. Efficacy analysis in the ITT population is shown in the table. Conclusions: In this population with very bad prognosis, our study met its primary endpoint. Pts who received FOLFOXIRI + Bev benefit for a statistically significative PFS and ORR. OS showed a trend of benefit in the experimental arm. According to these results, FOLFOXIRI-Bev could be considered an adequate treatment option for pts with mCRC and ≥3 bCTCs. Clinical trial information: 2012-000846-37. [Table: see text]

Efficacy and safety of FOLFIRI/aflibercept in second-line treatment of metastatic colorectal cancer in a real-world population: Prognostic and predictive markers

PURPOSE

The phase III VELOUR trial demonstrated efficacy with combined FOLFIRI-aflibercept in patients with metastatic colorectal cancer previously treated with oxaliplatin with or without bevacizumab versus placebo. The effect of FOLFIRI-aflibercept in routine clinical practice was evaluated.

METHODS/PATIENTS

Overall survival (OS), progression-free survival (PFS), response and safety were analysed for 78 patients treated with FOLFIRI-aflibercept at six GITuD institutions. Exploratory analyses of prognostic and predictive markers of efficacy were performed.

RESULTS

Patients had good general status (PS 0-1 96.2%), tumours were mostly RAS-mutant (75.6%), synchronous (71.8%), and left-sided (71.8%). Prior therapy included bevacizumab (47.4%) and anti-EGFR agents (12.8%). PFS was longer for metachronous than synchronous tumours (11.0 vs 5.0 months, P = 0.028), and for left-colon tumours (7.0 vs 3.0 months, P = 0.044). RAS-mutant status, first-line treatment and primary tumour surgery did not impact PFS. The disease control rate was 70.5%. The most common grade 3/4 toxicities were neutropenia (15.3%), asthenia (10.3%), diarrhea and mucositis (6.4% each). Dysphonia was reported in 39.7% of patients, and grade 3 hypertension in 3.8%. Development of hypertension (any grade) was significantly associated with a reduced risk of progression by multivariate analysis (HR = 2.7; 95%CI 1.3-5.4; P = 0.001).

CONCLUSIONS

Efficacy with FOLFIRI-aflibercept in a real-life population was in line with results from the pivotal trial and toxicity was manageable with treatment adaptation. Survival outcomes were not impacted by primary tumour location, RAS-mutant status, first-line treatment or primary tumour surgery. Hypertension may be a surrogate marker of efficacy in this patient population.

Co-occurrence and seasonal and environmental distributions of the sandflies Lutzomyia longipalpis and Nyssomyia whitmani in the city of Puerto Iguazú, northeastern Argentina

The aim of this work was to study the distribution of Phlebotominae (Diptera: Psycodidade) abundance in time and space in an area in northeastern Argentina with vector transmission of visceral and tegumentary leishmaniasis. For this, 51 households were selected using a 'worst scenario' criterion where one light trap was set during two consecutive nights in peridomiciles in the transitions between the four seasons, and the environment was surveyed simultaneously. The relationships of phlebotomine assemblage structure and the most abundant species with seasonality and environmental variables were evaluated using a canonical correspondence analysis and generalized linear mixed models, respectively. A total of 5110 individuals were captured. Lutzomyia longipalpis (Lutz & Neiva, 1912) and Nyssomyia whitmani (Antunes & Coutinho, 1939) were the most abundant species captured in all samplings (98.3% of the total capture). The period of highest abundance of Lu. longipalpis was early autumn, and it was distributed in the most urbanized areas. Nyssomyia whitmani occupied mainly the less urbanized areas, showing peaks of abundance in early spring and summer. Other species were captured in low numbers and showed seasonal-spatial variations similar to those of Ny. whitmani. We confirmed Leishmania spp. vector persistence throughout the year in spatial patches of high abundance even during the less favorable season.

Prognostic and predictive markers of response to treatment in patients with locally advanced unresectable and metastatic pancreatic adenocarcinoma treated with gemcitabine/nab-paclitaxel: Results of a retrospective analysis

BACKGROUND

Recent studies support the use of gemcitabine and nab-paclitaxel in adults with locally advanced unresectable or metastatic pancreatic adenocarcinoma although insufficient data are available on prognostic and predictive markers of response to treatment.

OBJECTIVE

The objective of this study is to identify treatment response markers in patients with locally advanced unresectable or metastatic pancreatic adenocarcinoma.

MATERIALS AND METHODS

This is an observational, retrospective, and multicenter study. Sociodemographic, clinical, and therapeutic data were collected. Cox regression models were applied to determine associations.

RESULTS

In total, 39 patients were included; 23.1% presented locally advanced pancreatic cancer and 76.9% metastatic disease. They received a mean of 6 ± 3 treatment cycles; 59% required dose reduction, 59% treatment delay, and 20.5% switched to a biweekly regimen. The overall response rate was 23% and the disease control rate was 81%. Median progression-free survival was 9 months and median overall survival (OS) was 15 months. A higher neutrophil/lymphocyte ratio (NLR) was significantly associated with lower OS. We reported Grades 1-4 nonhematological and hematological toxicities.

CONCLUSION

NLR is a useful prognostic factor for OS in patients with locally advanced unresectable or metastatic pancreatic adenocarcinoma treated with gemcitabine and nab-paclitaxel. Moreover, we suggest that a biweekly regimen is an option for certain groups of patients.

A prospective international Aspergillus terreus survey: an EFISG, ISHAM and ECMM joint study

OBJECTIVES

A prospective international multicentre surveillance study was conducted to investigate the prevalence and amphotericin B susceptibility of Aspergillus terreus species complex infections.

METHODS

A total of 370 cases from 21 countries were evaluated.

RESULTS

The overall prevalence of A. terreus species complex among the investigated patients with mould-positive cultures was 5.2% (370/7116). Amphotericin B MICs ranged from 0.125 to 32 mg/L, (median 8 mg/L).

CONCLUSIONS

Aspergillus terreus species complex infections cause a wide spectrum of aspergillosis and the majority of cryptic species display high amphotericin B MICs.

Austromegabalanus psittacus barnacle shell structure and proteoglycan localization and functionality

Comparative analyzes of biomineralization models have being crucial for the understanding of the functional properties of biominerals and the elucidation of the processes through which biomacromolecules control the synthesis and structural organization of inorganic mineral-based biomaterials. Among calcium carbonate-containing bioceramics, egg, mollusk and echinoderm shells, and crustacean carapaces, have being fairly well characterized. However, Thoraceca barnacles, although being crustacea, showing molting cycle, build a quite stable and heavily mineralized shell that completely surround the animal, which is for life firmly cemented to the substratum. This makes barnacles an interesting model for studying processes of biomineralization. Here we studied the main microstructural and ultrastructural features of Austromegabalanus psittacus barnacle shell, characterize the occurrence of specific proteoglycans (keratan-, dermatan- and chondroitin-6-sulfate proteoglycans) in different soluble and insoluble organic fractions extracted from the shell, and tested them for their ability to crystallize calcium carbonate in vitro. Our results indicate that, in the barnacle model, proteoglycans are good candidates for the modification of the calcite crystal morphology, although the cooperative effect of some additional proteins in the shell could not be excluded.

Aflibercept for metastatic colorectal cancer: safety data from the Spanish named patient program

OBJECTIVE

Aflibercept increased overall survival with acceptable tolerability in metastatic colorectal cancer (mCRC) when it was used in combination with FOLFIRI after progression on a first-line oxaliplatin regimen (VELOUR study). The safety profile of aflibercept in day-to-day clinical practice was assessed.

DESIGN AND METHODS

A named patient program provided early access to aflibercept to mCRC patients in Spain before its commercialization. Patients received aflibercept 4 mg/kg intravenous + FOLFIRI every 2 weeks as second-line treatment. A descriptive safety analysis was conducted.

RESULTS

Data from 89 mCRC patients were analyzed (male: 61.8%; median age: 62 years [interquartile range: 55, 67]; Eastern Cooperative Oncology Group 0 - 1: 95.5%). Fifty four (60.7%) patients presented ≥ 2 metastasis [liver (83.1%), lung (44.9%) or lymph nodes (33.7%)]. Most patients had previously received bevacizumab (60.7%) or anti-EGFR (19.1%) therapy. Patients received a median of 6.0 (interquartile range: 4, 13) cycles of FOLFIRI + aflibercept. Most grade ≥ 3 adverse events (AEs) were reported during the initial cycles of treatment. AEs possibly related to treatment occurred in 39 (43.8%) patients. Common grade ≥ 3 treatment-related AEs were neutropenia (7.9%), diarrhea (4.5%) and hypertension (3.4%).

CONCLUSIONS

In clinical practice, aflibercept + FOLFIRI is well tolerated, with a manageable toxicity profile. The safety results confirm the findings from the confirmatory VELOUR trial.

Retrospective analysis of prognostic and predictive markers in patients with locally advanced unresectable and metastatic pancreatic adenocarcinoma treated with gemcitabine/nabpaclitaxel: Influence of the presence of stent

483

Background: Placement of a biliary stent is a standard measure for patients (pts) with pancreatic cancer. We evaluated prognostic/predictive factors that could predict the benefit of gemcitabine/nabpaclitaxel in pts with locally advanced unresectable and metastatic pancreatic adenocarcinoma and whether the presence of a biliary stent reduced the treatment efficacy Methods: We retrospectively analyzed 39 pts with locally advanced and metastatic pancreatic cancer treated with gemcitabine/nabpaclitaxel. Data included lactate dehydrogenase (LDH) level, alkaline phosphatase, neutrophil/lymphocyte ratio (NLR), performance status (PS), weight loss, presence of stent, analgesics use and CA 19.9 level. The correlation with response rate, progression-free survival (PFS) and overall survival (OS) was analyzed. Objective toxicities were assessed. Results: 30 pts (77%) had metastatic disease and 9 (23%) locally advanced pancreatic cancer. 46% had liver metastases and 41% lung metastases. Mean age of pts: 62 years (62% male). 20% had PS:0, 67% PS:1 and 13% PS:2. Stents were placed in 30% of pts, 69% had weight loss and 64% used analgesics at diagnosis. At the time of analysis 14 pts had died (25 alive). 56% had progressed, 3% were lost to follow-up and 41% had not progressed. A total of 54% disease stabilizations, 21% partial responses and 18% progressions were achieved (deaths: 7%). 43% required dose reduction. The main toxicity was hematologic (grade 1 anemia). Median PFS: 6 months (95%CI 4.4-7.6). Median OS: 15 months (95%CI 10.4-19.6). There was a statistically significant relationship between LDH level, NLR and PS and OS: LDH level higher than 363 increased the risk of death, NLR above 3.1 increased 1.8 times the risk of death and mean OS of pts with ECOG:0,1 was greater than that of pts with ECOG:2. No relationship between the presence of stent and PFS or OS was found, as well as with any of the other variables. Conclusions: The presence of stent did not reduce the efficacy of gemcitabine/nabpaclitaxel. Univariate analysis showed PS as a prognostic factor while multivariate showed LDH and NLR.

Phase II trial of erlotinib plus capecitabine as first-line treatment for metastatic pancreatic cancer (XELTA study)

AIM

To evaluate the efficacy and safety of erlotinib plus capecitabine for metastatic pancreatic cancer.

PATIENTS AND METHODS

This was a multicenter, uncontrolled, phase II trial. Patients with untreated metastatic pancreatic cancer received oral capecitabine at 1,000 mg/m(2) twice daily on days 1-14, of a 21-day treatment cycle; and oral erlotinib at 150 mg daily.

RESULTS

Thirty-two patients were enrolled. The overall response rate (ORR) was 6%, with a median time to treatment failure of 2.1 months. The median follow-up was 7.6 months. The median progression-free survival was 2.1 months and median overall survival was 4.3 months. The one-year survival rate was 22%. Major grade 1 and 2 non-hematological toxicities were skin rash (34%), asthenia (31%) and diarrhea (31%). Grade 3 hematological toxicity was <13%. No grade 4 toxicities were detected. None of the patients died due to treatment toxicity.

CONCLUSION

The combination of capecitabine with erlotinib is an active regimen with a favorable safety profile for patients with metastatic pancreatic cancer.

Evaluation of a multilayered chitosan-hydroxy-apatite porous composite enriched with fibronectin or an in vitro-generated bone-like extracellular matrix on proliferation and diferentiation of osteoblasts

The use of extracellular matrix (ECM) molecules from tissues is an interesting way to induce specific responses of cells grown onto composite scaffolds to promote adhesion, proliferation and differentiation. There have been several studies on the effects on cell proliferation and differentiation of osteoprogenitor cells cultured onto composites, either adding some ECM molecules or grown in the presence of growth factors. Other studies involve the use of osteoblasts cultured on a three-dimensional (3D) matrix, enriched with ECM molecules produced by the same cells grown previously inside the composite. Here, the effect of enrichment of a novel multilayered chitosan-hydroxyapatite composite with ECM molecules produced by osteoblasts, or the addition of 25 or 50 µg/ml fibronectin to the composite, on proliferation and differentiation of osteoblasts cultured on these composites was studied. The results showed an increase in the number of osteoblasts from day 1 of culture, which was higher in the group grown onto composites enriched with the highest concentration of fibronectin or with ECM molecules produced naturally by osteoblasts cultured previously on them, when compared with the control group. However, this increment tended to decline in all groups after day 7 of culture, the day when they reached the highest peak of proliferation. Differentiation expressed as alkaline phosphatase activity followed the proliferation pattern of the cells cultivated on the scaffolds. The results demonstrate the potential offered by these enriched 3D multilayered composites for improving their ability as bone grafting material.

[Trapped epidural catheter: reconstruction of computed tomography images]

A trapped epidural catheter without a knot is a rare complication. During placement of an epidural catheter for analgesia during labor, resistance made it impossible to position the catheter within the epidural space. A second catheter was inserted to provide the required analgesia. When the second catheter was removed, computed tomography (CT) revealed that the tip of the first catheter was close to the the right facet joint space. A second attempt to extract the catheter failed. In light of this situation, the patient was seated with the spine slightly bent to one side, a guidewire was inserted through the catheter lumen, and the catheter and guidewire were gently pulled; the catheter was extracted without causing the tip to break up. Three-dimensional CT reconstruction allowed the catheter tip and characteristics of the joint surfaces to be observed. We discuss protcols and alternative strategies that can be followed when an epidural catheter is difficult to remove, including the most appropriate images to use for guidance.

[Breast metastasis as initial presentation of a renal carcinoma]

OBJECTIVES

To report the case of a breast metastasis as initial presentation of renal carcinoma.

METHODS

72-year-old male patient who consulted for a painful right breast tumor. We describe clinical history, complementary tests, biopsy and treatment.

RESULTS

Pathologic study confirmed a metastasis of a renal clear cell carcinoma. A CT scan confirmed the existence of bilateral renal tumors.

CONCLUSIONS

Breast metastases are exceptional as initial presentation of a renal carcinoma. We performed a bibliographic review on the topic.

Prospective comparison of clinical and echocardiographic diagnosis of rheumatic carditis: long term follow up of patients with subclinical disease

OBJECTIVE

To determine the frequency of occurrence and long term evolution of subclinical carditis in patients with acute rheumatic fever.

DESIGN

Valvar incompetence was detected by clinical examination and Doppler echocardiographic imaging during the acute and quiescent phases of rheumatic fever. Patients were followed prospectively and submitted to repeat examinations at one and five years after the acute attack. Persistence of acute mitral and aortic lesions detected solely by echocardiography (subclinical disease) was compared with that of disease detected by clinical examination as well (thereby fulfilling the latest 1992 Jones criteria for rheumatic carditis).

SETTING

Three general hospitals with a university affiliation in Chile.

PATIENTS

35 consecutive patients fulfilling the revised Jones criteria for rheumatic fever. Clinical and echocardiographic examination was repeated in 32 patients after one year and in 17 after five years. Ten patients had subclinical carditis on admission, six of whom were followed for five years.

MAIN OUTCOME MEASURES

Auscultatory and echocardiographic evidence of mitral or aortic regurgitation during the acute attack or at follow up.

RESULTS

Mitral or aortic regurgitation was detected by Doppler echocardiographic imaging in 25/35 rheumatic fever patients as opposed to 5/35 by clinical examination (p = 0.03). Doppler echocardiography revealed acute valvar lesions in 10 of 20 rheumatic fever patients who had no auscultatory evidence of rheumatic carditis (subclinical carditis). Three of these subclinical lesions and three of the clinical or auscultatory lesions detected on admission were still present after five years of follow up, emphasising that subclinical lesions are not necessarily transient.

CONCLUSIONS

Doppler echocardiographic imaging improves the detection of rheumatic carditis. Subclinical valve lesions, detected only by Doppler imaging, can persist. Echocardiographic findings should be accepted as a major criterion for the diagnosis of rheumatic fever.

Escherichia coli membrane fluidity as detected by excimerization of dipyrenylpropane: sensitivity to the bacterial fatty acid profile

A coordinated study of membrane fluidity and fatty acid composition has been carried out in Escherichia coli W3110. The lipid acyl chain profile of the bacteria, altered by growing cells in steady state at 30, 37, 42, or 45 degrees C, was determined by gas chromatography of the fatty acid methyl esters. In parallel experiments, total membranes obtained from cells of the above-mentioned cultures were labeled with dipyrenylpropane and their relative fluidity was measured on the basis of the excimer to monomer fluorescence intensity ratio of the fluorophore. It has been found that, at constant assay temperature, fluidity determined with dipyrenylpropane decreases gradually with the growth temperature increment, from 30 to 45 degrees C. Interestingly, when fatty acid composition is taken into account, fluidity increases linearly in the range under study, with the proportion of unsaturated fatty acyl chains, both variables being highly correlated (0.924 </= r(2) </= 0.996). Our results show that dipyrenylpropane is a reliable and quantitative indicator of changes in membrane fluidity, driven by modifications in the acyl chain composition of bacterial lipids.

[Single-system ectopic ureters. A review of 19 cases]

Single system ectopic ureters are usually associated with multiple congenital abnormalities and the corresponding renal units is frequently abnormal. 19 cases of single system ectopic ureters were diagnosed and treated in our hospital during the last 20 years. The patients were less than 11 years old. The abnormality was bilateral in two cases and the 63% of all had associated malformations, being the anorectal abnormalities the most frequent. The incidence of reflux into the ectopic ureter was 57%, and the association to unilateral or contralateral renal agenesis, 26.3%. Thirteen ectopic ureters were reimplanted successfully into the bladder, and the cases of nonfunctioning kidneys were removed (nephroureterectomy). The follow-up period was 10 months to 14 years, developing the 68% of the cases without any complication and a good renal function. Two patients were transplanted due to a kidney failure. Diagnosis is often extremely difficult and requires a high degree of suspicion. This diagnosis may be incidental, and it may be made during investigation of patients with other malformations. An early diagnosis and treatment must be made in order to avoid a disturbance of renal function. We wish to point up the high incidence of reflux into the ectopic ureter and the high association to renal agenesis in the single system ectopic ureters in comparison with ectopic ureter of duplex system.

Spontaneous biliary perforation and necrotizing enterocolitis

A case of spontaneous bile-duct perforation in a 5-month-old boy with a history of necrotizing enterocolitis in his 1st week of life is reported. To our knowledge, this is the second case reported with such an antecedent, supporting a vascular etiology for some cases of spontaneous biliary perforation.

Fatty acid profile of Escherichia coli during the heat-shock response

The possible changes in the fatty acid profile of Escharichia coli during heat-shock have been investigated. Bacteria growing in steady-state at 30 degrees C were subjected to an abrupt temperature upshift to 45 degrees C and held at the high temperature for various periods of time in order to elicit the heat-shock response. Fatty acid compositions of lipids extracted from samples taken at different times after the temperature upshift, as well as from cultures in steady-state at 30 and 45 degrees C, were determined by gas-chromatography. It has been found that the total unsaturates to total saturates ratio decreases gradually during heat-shock and that 30 min after the temperature jump, the reduction is equivalent to 57% of the difference between ratios corresponding to steady-state cultures at 30 and 45 degrees C. Consistent with this remodeling of lipid acyl chains, there is a decrease in the excimerization rate of the fluidity probe dipyrenylpropane incorporated into sonicated E. coli lipid extracts. Such modifications occur within the time-span of the heat-shock response, as judged from our previous measurements of the kinetics of change in heat-shock proteins induction ratio. Together, these results indicate that the control of membrane fluidity during the heat-shock response can be accounted for, at least in part, by an important change in the fatty acid composition of Escherichia coli lipids.

[Laparoscopic transsection of Ladd's bands: a new indication for therapeutic laparoscopy in neonates]

Within the last ten years and by the introduction of some new instruments, laparoscopy is a safe and effective method that has been further extended in children. We report our experience in the treatment of laparoscopy on a seven day old newborn affected by malrotation with an intermittent duodenal obstruction. The treatment consisted of a duodenal liberation after the section was easily performed in congenital Ladd's bands. The spiral twists of the small intestine found in the upper gastrointestinal series, disappeared in a new study done after surgery. We consider this operation as a new indication for an operative laparoscopy. It allows a good visualization of this congenital abnormality, and it is easy to perform with a significantly reduced operative trauma.

Long-gap esophageal atresia: reconstruction preserving all portions of the esophagus by Schärli's technique

For distances of over 4-5 cm, esophageal replacement is almost always necessary in esophageal atresias. We present the technical details and describe our experience with esophageal reconstruction by elongation of the lesser curvature (Schärli's technique) in four cases of very long atresias. A retrosternal transposition was made without a thoracotomy in two children, and an orthotopic mediastinal route through a right thoracotomy was done in two others. There were two main complications: anastomotic leaks in three patients that closed spontaneously, and too-rapid gastric emptying, resulting in dumping symptoms that improved with time and diet. One patient developed an anastomotic stricture that responded to bouginage, while another had temporary feeding problems. Esophageal reconstruction by elongation of the lesser curvature provides a relatively simple method of esophageal replacement in children in that all portions of the esophagus are preserved. We propose this technique for early establishment of esophageal continuity in neonates.

The interaction of phospholipase A2 with liposomes: an immunological approach to its study

Porcine pancreatic phospholipase A2 (PLA2) has been incubated for 2 hours at 34 degrees C with rabbit anti-pig pancreatic PLA2 polyclonal antiserum in the absence or presence of phosphatidylcholine liposomes in different physical states. Subsequent assay of hydrolysis -triggered through addition of 5 mM Ca2+- at 34 degrees C, shows that preincubation with antiserum in the presence of 1,2-dimyristoyl-3-sn-phosphatidylcholine liquid-crystalline vesicles, renders the PLA2 activity undetectable, similarly to what is found if preincubation is carried out in the absence of liposomes. In contrast, 1,2-dipalmitoyl-3-sn-phosphatidylcholine liposomes, which at 34 degrees C are in the gel-phase, protect the enzyme from the antiserum effect. The results are consistent with a stronger binding of PLA2 to gel phase, as compared to liquid crystalline vesicles and suggest that through the physical interaction with liposomes in the gel state, the enzyme is shielded from reaction with the antibodies. Taking into account the characteristic hydrolysis profiles of vesicles in different physical states, it can be concluded that the above interpretation agrees with the proposal that PLA2-membrane association promotes the interfacial activation of the enzyme.

Role of type X collagen on experimental mineralization of eggshell membranes

Type X collagen is a transient and developmentally regulated collagen that has been postulated to be involved in controlling the later stages of endochondral bone formation. However, the role of this collagen in these events is not yet known. In order to understand the function of type X collagen, if any, in the process of biomineralization, the properties of type X collagen in eggshell membranes were further investigated. Specifically, calvaria-derived osteogenic cells were tested for their ability to mineralize eggshell membranes in vitro. Immunohistochemistry with specific monoclonal antibodies was used to correlate the presence or absence of type X collagen or its propeptide domains with the ability of shell membranes to be mineralized. The extent of mineralization was assessed by Von Kossa staining, scanning electron microscopy and energy-dispersive spectroscopy. The results indicate that the non-helical domains of type X collagen must be removed to facilitate the cell-mediated mineralization of eggshell membranes. In this tissue, intact type X collagen does not appear to stimulate or support cell-mediated mineralization. We postulate that the non-helical domains of type X collagen function in vivo to inhibit mineralization and thereby establish boundaries which are protected from mineral deposition.

Cantrell's pentalogy. Report of four cases and their management

Four neonates with the uncommon Cantrell's pentalogy seen in our hospital within a 6-month period without any apparent factor in common are described, with a review of the world literature. The first case was diagnosed prenatally at 15 weeks' gestation, the earliest intrauterine finding in the literature. The occurrence of imperforate anus with the syndrome, observed in one of the cases, has not been previously reported. Two were operated upon and only one of the four survived. This high mortality was confirmed by similar cases reported by other authors.

[Solid ovarian tumors in childhood]

We evaluate our experience in solid ovarian tumors at the Children's Hospital La Fe. The main aims of the study were finding out relevant clinical data for a correct clinical approach, and the optimal surgical attitude in order to obtain tumor relieving with preservation of fertility when possible. A review of 28 girls under 14 years with solid ovarian tumors was carried out. Previous history, initial symptoms and signs, analytical and radiological explorations, treatment and evolution were analysed. 17 benign and 11 malignant tumors were found. Main clinical data were acute abdominal pain and palpation of a mass. Surgery was performed in all of them: salpyngo-oophorectomy in 23 and oophorectomy in 5, with tumoral resection. All patients survive, with periodic follow-up. We remark the frequency of acute abdominal pain as initial symptom of an ovarian tumor, and the importance of a surgical attitude that, intending to be curative, would preserve fertility.

[Our experience in portal cavernomatosis in childhood: cross-sectional study and analysis of results]

A retrospective and transversal study of our patients with portal cavernomatosis is developed, with the aim of comparing the evolution and the present status of the patients that have undergone different therapeutical approaches. Between 1975 and 1995, 15 patients with portal cavernomatosis have been treated. Personal history, signs and symptoms at the moment of diagnosis, and treatment were analyzed. Now, the controls have been made by physical examination and ECO-Doppler of the espleno-portal system. In 6 cases the absence of bleeding made surgery unnecessary. In the 9 patients with digestive haemorrhage, it could be controlled pharmacologically, with a later surgical approach. Now, all non-operated and 6 operated patients show splenomegaly, without bleeding. The ECO-Doppler shows colateral flow, the splenomegaly in the non-operated and the surgical shunts and the hepatofugal circulation in the operated patients. Looking at our results, we believe that prophylactic surgery is not indicated. In those cases of digestive bleeding, surgery after the complete resolution of the acute disease shows good results at a short and long term.

Congenital intrahepatic portocaval shunt associated with trimethylaminuria

A case of congenital portal-systemic shunting due to an intrahepatic connection diagnosed by ultrasound scanning and color Doppler in an 8-month-old girl is reported. She began to manifest trimethylaminuria 3 years later. At 7 years of age, she is asymptomatic without therapeutic measures except for diet. This is the seventh reported case and the third in a child to our knowledge.

[Ureteral ectopia in pediatric age: treatment and evolution in 55 cases]

In the last twenty years 55 children with ureteral ectopia were diagnosed and treated in our Hospital. Thirty seven of them were female (67.3%) and they presented the urinary tract infection like the most frequent symptomatology. Seven children were diagnosed during the first days after being born because the detection of hydronephrosis in the antenatal ultrasound; 36 were associated with complete ureteric duplication (65.4%) and the other 19 with single system (34.6%). Congenital abnormalities associated were seen in 14 patients with more frequency in those which presented single-system ectopic ureter (12/14), being the imperforate anus and the kidney agenesia those the most incidence. The most frequent points of opening were the bladder neck and posterior uretra. Diagnostic work-up included some radiological studies (abdominal ultrasound, intravenous urography, sequence mictional cystourethrography and vaginogram), isotopical tests, meticulous genital exploration, cystoscopy and vaginoscopy. 49.1% underwent conservative surgical treatment (7 ipsilateral ureteroureterostomy and 20 ureteral reimplantation) and 50.9% underwent total or partial nephroureterectomy, being the type of treatment depended on functionality of renal units. After treatment, 74.5% had not any incident; among all postsurgical complications, reflux reappearance was the most frequent (3 cases).

[The use of color doppler sonography of the acute scrotum in children]

The differential diagnosis of the causes of acute scrotum only by clinical means, is often very difficult and supposes the risk of making mistakes, which leaves to several unnecessary surgical explorations. By Colour Doppler Sonography we get some information about testicular flow that helps us in the diagnosis. During the last two years 72 consecutive cases of acute scrotum in children younger than 13 years old, were seen in our hospital emergency department. They all underwent testicular bilateral sonography with color flow imaging using a 7.5 MHz linear array transducer (Model Sonolayer Toshiba SSH-140 A). The sonographical diagnosis were: 45 epididymo-orchitis (62.5%), 8 testicular torsions (11%), 7 torsions of the appendix of testis (9.7%), 7 normal explorations (9.7%), 4 acute idiopathic scrotal oedema (5.5%) and a Henoch-Schönlein purpura (1.38%). Doppler examination showed a 97.2% sensibility and 72.2% specificity in the diagnosis of epididymo-orchitis and 88.88% sensibility and 100% specificity in the diagnosis of testicular torsion. The Colour Doppler Sonography should not minimize importance to the clinical explorations, but is very useful for the diagnosis of acute scrotal process, overcoat in inflammatory diseases.

[Treatment with Ethibloc of lymphangiomas and venous angiomas]

Lymphangioma and venous angioma are a group of pathological entities which have required surgical treatment since years. Extension, localization and poor delimitation of some lesions have resulted in technical difficulties and serious complications. Our group began the sclerosing therapy with an injection of fibrin adhesive and, due to the lack of response in the first patient, a program with Ethibloc as an alternative substance was developed. We present 10 cases, 4 lymphangiomas and 6 venous angiomas. In 50% of our patients one single session of sclerotherapy was made, in 25% two sessions, and in the rest 25% three. From 10 cases, 4 are still on treatment, complete remission in 5 cases, and good evolution in one case (mixed lymphangioma). As a long-term complication, we have noticed fistulization in 3 cases, and expulsion of the sclerosing agent. In our experience, percutaneous sclerosis with Ethibloc should be the first therapeutic alternative.

[Neonatal intravaginal testicular torsion in an undescended testis]

We report a case of intravaginal testicular torsion with an unusual debut in a 30 day old patient which had undescended testis. We emphasize the need of a complete physical exploration of the child that go to the emergency service with inspecific symptoms of abdominal pain, and supposing the hemiscrotum was empty, is essential to reject a torsion of a cryptorchidic testicle. An immediate surgery is necessary in order to diagnose and treat this disturbance.

Membrane fluidity of Escherichia coli during heat-shock

The excimer-forming fluorophore dipyrenylpropane has been used to measure the relative fluidity of total membranes isolated from Escherichia coli grown at 30 or 45 degrees C, or exposed to a heat-shock from 30 to 45 degrees C for various periods of time. Parallel experiments were performed using [35S]methionine pulse-labeling of cells, to study the induction of heat-shock proteins (HSPs) at different times after the sudden change in E. coli growth-temperature from 30 to 45 degrees C. Results suggest that upon an abrupt temperature upshift from 30 to 45 degrees C, membrane fluidity adjustment to the steady-state level at the high temperature, takes place during the E. coli heat-shock response.

Activity of phospholipase A2 on a fluorescent substrate incorporated into non-hydrolyzable phospholipid liposomes

The activity of phospholipase A2 (PLA2) on phospholipid liposomes depends on the physicochemical properties of the aggregated substrate, which are subject to continuous modification by the products released during hydrolysis. We propose here an experimental design that, by means of the incorporation of a fluorescent substrate at very low molar ratio (< or = 1:500) into a nonhydrolizable liposomal matrix of 1,2-dihexadecyl-sn-glycero-3-phosphocholine (DHPC), allows the study of hydrolysis by porcine pancreatic phospholipase A2, in virtual absence of physical perturbations of the lamellar phase, by the released products. We have been able to measure immediate hydrolysis of the fluorescent substrate 1,2-di-[omega(1'-pyreno)-decanoyl]-sn- glycero-3-phosphocholine when the sonicated liposomal matrix is in the gel phase. In the liquid crystalline state, in contrast, hydrolysis is very poor even after 80 min of adding the enzyme. Both in the gel and liquid-crystalline phases, incorporation of unlabeled PLA2 products activates the hydrolysis rate to comparable levels. It appears that the conformation adopted by the substrate immersed in the gel or liquid crystalline matrix is especially important in determining its susceptibility to hydrolysis in the absence of products.

Calcium ions reverse a latency period induced by bovine serum albumin in the time course of phospholipase A2 action on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes

The time course of hydrolysis of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes in the gel phase catalyzed by porcine pancreatic phospholipase A2 was studied at 1 mM NaCl and variable CaCl2 concentrations, in the presence of delipidated bovine serum albumin. It has been found that the duration of the latency induced by bovine serum albumin shows an inverse dependence with CaCl2 concentration. As we showed previously, the induction of a lag phase by bovine serum albumin is related to its ability to sequester the fatty acid newly released by hydrolysis. Based on this and on our observation that there is an inverse dependence between the length of the latency period and the interfacial calcium ion concentration, it is interpreted that, while a direct effect of bovine serum albumin is the diminution of the liposome negative surface charge density by sequestration of the fatty acid released during hydrolysis, an indirect effect could be the decrease in the surface Ca2+ concentration. This, in turn, should diminish the enzyme binding to the lipid-water interface. The appearance of a latency phase seems to be the final consequence of these events.

[Renal scintigraphy with captopril in the evaluation of renovascular hypertension]

The administration of an angiotensin-converting enzyme (ACE) inhibitor transitorily reduces the GFR in a kidney with renal artery stenosis, effect that can be ascertained with scintigraphic studies using ACE inhibitors. We evaluated the clinical usefulness of captopril renography (CR) in the diagnosis of renovascular hypertension (RVH) in 51 hypertensive patients in which this diagnosis was suspected. All subjects underwent angiography and RVH was diagnosed when renal artery stenosis exceeded 60%, there was lateralization of renal vein renin or there was a concordant clinical outcome. Renography was performed 15 minutes after Lasix administration, using Tc-99m DTPA, before and 60 minutes after the oral administration of 50 mg of captopril. The scintigraphic criteria for a positive test were a decreased split renal function, a delayed peak uptake, a decreased excretion of DTPA and a prolonged transit time. In three of 28 patients in whom angiography discarded RVH, CR was positive. In the 23 patients with confirmed RVH, CR was positive in 10 of 12 with unilateral stenosis, in 3 of 8 with bilateral stenosis and 1 of 3 with stenosis in a transplanted kidney. The overall sensitivity and specificity of the test for RVH was 60.9% and 89.2% respectively. There were no changes in blood pressure or adverse effects after captopril administration. We conclude that CR in RVH is useful to select patients for further studies (angiography) and to perform a functional interpretation of angiographic alterations.

Partial biochemical and immunochemical characterization of avian eggshell extracellular matrices

There is evidence to suggest that extracellular matrix molecules, such as proteoglycans, are involved in the regulation of mineral deposition in calcifying tissues. One mineralizing system which is characterized by extremely rapid mineralization is the hen eggshell. This eggshell consists of a pair of nonmineralized eggshell membranes subjacent to the calcified eggshell proper; the eggshell proper is organized into palisades (columns) of mineralized matrix separated by pores. Between the membranes and the shell proper are compacted foci of tissue called mammillary knobs, which are thought to be sites where mineralization is initiated. Previous work from this laboratory has shown the presence of types I, V, and X collagen in the shell membranes. To address the question of the possible role of proteoglycans and glycosaminoglycans in mineralization of the eggshell, two approaches were used. First, immunohistochemistry was performed with monoclonal antibodies to various proteoglycan and glycosaminoglycan epitopes. This analysis indicates that different glycosaminoglycans are localized to discrete regions within the eggshell. Dermatan sulfate is present within the matrix of the shell proper and, to a lesser extent, the mammillary knobs and the outer portion of the shell membranes. In contrast, keratan sulfate is found in the shell membranes and prominently in the mammillary knobs. Interestingly, different keratan sulfate antibodies immunostain distinct regions of the eggshell, which suggests that various types of keratan sulfate are distributed differently. The second approach utilized was to extract the eggshell membranes and recover anionic molecules by anion-exchange chromatography. This resulted in the extraction of material which was recognized by antibodies to keratan sulfate, but not to chondroitin sulfate. This material was very large, as evidenced by its elution in the void volume of a Sepharose CL-2B column. The large size may be due to the extensive cross-links known to occur in the eggshell. If eggshell membranes are extracted at elevated temperature, the material recovered is of much smaller size. These results indicate that molecules recognized by antibodies to glycosaminoglycans are present in the eggshell, and their localized distribution relative to the calcified matrix suggests that they may be involved in the regulation of mineral deposition.

[Sexually transmitted diseases: notification in Chile, in the V region and in the Vinã Del Mar-Quillota health service (1977-1988)]

Reports of sexually transmitted diseases in the Vth Region of Chile from 1977 to 1988 were analyzed and compared to nationwide reports and to figures for the Viña del Mar-Quillota area. Overall rates of syphilis decreased during the period. In contrast both number of cases and risk of disease increased for gonorrhoea. Risk of syphilis and gonorrhoea was highest in the Vth Region. HIV infection is increasing, especially in the area covered by the Health Service in Viña del Mar-Quillota. Sexually transmitted diseases not subject to reports were screened along with routine examinations for cancer of the cervix. Infection rates of 9.9% for trichomona and 1.09% for candida were thus detected.

Dependence on neutral salt concentration of the latency phase in the time course of hydrolysis of dimyristoylphosphatidylcholine liposomes by phospholipase A2

The time course of the hydrolytic action of porcine pancreatic phospholipase A2 on sonicated dimyristoylphosphatidylcholine liposomes in the presence of variable NaCl concentrations has been studied at temperatures between 17 and 36 degrees C; at these temperatures liposomes are in the gel phase. At a NaCl concentration of 10 mM, the hydrolysis shows a small and constant lag period of 6-8 min at all temperatures within this range. As the temperature is raised into the liquid crystalline range, the latency phase lengthens monotonically so that at 36 degrees C it reaches 55 min. An increase in the NaCl concentration to 1 M makes the lag period longer at all temperatures studied, with the exception of the phase transition range (near 24 degrees C); within this temperature range, a small reduction in the lag time is observed. The increase in the length of the latency period at high salt concentrations may be due to screening of the negative surface charge generated by the nascent fatty acid which seems to be essential for the efficient interfacial binding of the enzyme. In the phase transition range of the lamellae, the unfavorable effect of high salt concentrations on the electrostatic binding of the enzyme appears to be overcome by another type of interaction. Recent findings raise the possibility that this interaction could be hydrophobic in nature.