A case-control study of a combination of single nucleotide polymorphisms and clinical parameters to predict clinically relevant toxicity associated with fluoropyrimidine and platinum-based chemotherapy in gastric cancer

Background

Fluoropyrimidine plus platinum chemotherapy remains the standard first line treatment for gastric cancer (GC). Guidelines exist for the clinical interpretation of four DPYD genotypes related to severe fluoropyrimidine toxicity within European populations. However, the frequency of these single nucleotide polymorphisms (SNPs) in the Latin American population is low (< 0.7%). No guidelines have been development for platinum. Herein, we present association between clinical factors and common SNPs in the development of grade 3–4 toxicity.

Methods

Retrospectively, 224 clinical records of GC patient were screened, of which 93 patients were incorporated into the study. Eleven SNPs with minor allelic frequency above 5% in GSTP1, ERCC2, ERCC1, TP53, UMPS, SHMT1, MTHFR, ABCC2 and DPYD were assessed. Association between patient clinical characteristics and toxicity was estimated using logistic regression models and classification algorithms.

Results

Reported grade ≤ 2 and 3–4 toxicities were 64.6% (61/93) and 34.4% (32/93) respectively. Selected DPYD SNPs were associated with higher toxicity (rs1801265; OR = 4.20; 95% CI = 1.70–10.95, p = 0.002), while others displayed a trend towards lower toxicity (rs1801159; OR = 0.45; 95% CI = 0.19–1.08; p = 0.071). Combination of paired SNPs demonstrated significant associations in DPYD (rs1801265), UMPS (rs1801019), ABCC2 (rs717620) and SHMT1 (rs1979277). Using multivariate logistic regression that combined age, sex, peri-operative chemotherapy, 5-FU regimen, the binary combination of the SNPs DPYD (rs1801265) + ABCC2 (rs717620), and DPYD (rs1801159) displayed the best predictive performance. A nomogram was constructed to assess the risk of developing overall toxicity.

Conclusion

Pending further validation, this model could predict chemotherapy associated toxicity and improve GC patient quality of life.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08745-0.

Validation of an NGS Panel Designed for Detection of Actionable Mutations in Tumors Common in Latin America

Next-generation sequencing (NGS) is progressively being used in clinical practice. However, several barriers preclude using this technology for precision oncology in most Latin American countries. To overcome some of these barriers, we have designed a 25-gene panel that contains predictive biomarkers for most current and near-future available therapies in Chile and Latin America. Library preparation was optimized to account for low DNA integrity observed in formalin-fixed paraffin-embedded tissue. The workflow includes an automated bioinformatic pipeline that accounts for the underrepresentation of Latin Americans in genome databases. The panel detected small insertions, deletions, and single nucleotide variants down to allelic frequencies of 0.05 with high sensitivity, specificity, and reproducibility. The workflow was validated in 272 clinical samples from several solid tumor types, including gallbladder (GBC). More than 50 biomarkers were detected in these samples, mainly in BRCA1/2, KRAS, and PIK3CA genes. In GBC, biomarkers for PARP, EGFR, PIK3CA, mTOR, and Hedgehog signaling inhibitors were found. Thus, this small NGS panel is an accurate and sensitive method that may constitute a more cost-efficient alternative to multiple non-NGS assays and costly, large NGS panels. This kind of streamlined assay with automated bioinformatics analysis may facilitate the implementation of precision medicine in Latin America.

Simvastatin interferes with cancer 'stem-cell' plasticity reducing metastasis in ovarian cancer

Cell plasticity of 'stem-like' cancer-initiating cells (CICs) is a hallmark of cancer, allowing metastasis and cancer progression. Here, we studied whether simvastatin, a lipophilic statin, could impair the metastatic potential of CICs in high-grade serous ovarian cancer (HGS-ovC), the most lethal among the gynecologic malignancies. qPCR, immunoblotting and immunohistochemistry were used to assess simvastatin effects on proteins involved in stemness and epithelial-mesenchymal cell plasticity (EMT). Its effects on tumor growth and metastasis were evaluated using different models (e.g., spheroid formation and migration assays, matrigel invasion assays, 3D-mesomimetic models and cancer xenografts). We explored also the clinical benefit of statins by comparing survival outcomes among statin users vs non-users. Herein, we demonstrated that simvastatin modifies the stemness and EMT marker expression patterns (both in mRNA and protein levels) and severely impairs the spheroid assembly of CICs. Consequently, CICs become less metastatic in 3D-mesomimetic models and show fewer ascites/tumor burden in HGS-ovC xenografts. The principal mechanism behind statin-mediated effects involves the inactivation of the Hippo/YAP/RhoA pathway in a mevalonate synthesis-dependent manner. From a clinical perspective, statin users seem to experience better survival and quality of life when compared with non-users. Considering the high cost and the low response rates obtained with many of the current therapies, the use of orally or intraperitoneally administered simvastatin offers a cost/effective and safe alternative to treat and potentially prevent recurrent HGS-ovCs.

Platelets enhance tissue factor protein and metastasis initiating cell markers, and act as chemoattractants increasing the migration of ovarian cancer cells

Background

An increase in circulating platelets, or thrombocytosis, is recognized as an independent risk factor of bad prognosis and metastasis in patients with ovarian cancer; however the complex role of platelets in tumor progression has not been fully elucidated. Platelet activation has been associated with an epithelial to mesenchymal transition (EMT), while Tissue Factor (TF) protein expression by cancer cells has been shown to correlate with hypercoagulable state and metastasis. The aim of this work was to determine the effect of platelet-cancer cell interaction on TF and “Metastasis Initiating Cell (MIC)” marker levels and migration in ovarian cancer cell lines and cancer cells isolated from the ascetic fluid of ovarian cancer patients.

Methods

With informed patient consent, ascitic fluid isolated ovarian cancer cells, cell lines and ovarian cancer spheres were co-cultivated with human platelets. TF, EMT and stem cell marker levels were determined by Western blotting, flow cytometry and RT-PCR. Cancer cell migration was determined by Boyden chambers and the scratch assay.

Results

The co-culture of patient-derived ovarian cancer cells with platelets causes: 1) a phenotypic change in cancer cells, 2) chemoattraction and cancer cell migration, 3) induced MIC markers (EMT/stemness), 3) increased sphere formation and 4) increased TF protein levels and activity.

Conclusions

We present the first evidence that platelets act as chemoattractants to cancer cells. Furthermore, platelets promote the formation of ovarian cancer spheres that express MIC markers and the metastatic protein TF. Our results suggest that platelet-cancer cell interaction plays a role in the formation of metastatic foci.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1304-z) contains supplementary material, which is available to authorized users.

[In vitro cell response to chemotherapeutic agents, to personalize ovarian cancer treatment: report of two cases]

Our laboratory has implemented an in vitro assay to estimate the response to chemotherapy in ovarian cancer cells pertaining to individual patients. In two selected patients, we determined the correlation between an in vitro assay of cells from suspected ovarian cancer ascites, with the clinical chemotherapy response. Cancer cells isolated from peritoneal fluid with suspected ovarian cancer were tested for cytotoxicity with corresponding chemotherapy regimens. Circulating Cal25 levels and attending physician consultation determined clinical course and response to chemotherapy. The in vitro assay result correlated with Cal25 levels, progression free survival and attending physician evaluation. The assay predicted correctly the failure of two successive chemotherapy regimes in the first patient, while predicting a favorable clinical response in the second subject.

Development and validation of I-DNA1: a 15-Loci multiplex system for identity testing

This paper presents a system for the multiplex amplification of 15 loci, known as I-DNA1, which combines mini and midiSTR technology, with amplicon sizes ranging from 49 to 297 bp. I-DNA1 analyses all the STR loci included in the CODIS and the Interpol Standard Set of loci, nine of the ten European core loci and seven of the eight German core loci, making it suitable for use in identifying humans. Moreover, its high sensitivity and the small size of its amplicons mean that I-DNA1 is potentially highly useful for analysing highly degraded and/or very small DNA samples.

Mutation rates at Y chromosome specific microsatellites

A collaborative work was carried out by the Spanish and Portuguese ISFG Working Group (GEP-ISFG) to estimate Y-STR mutation rates. Seventeen Y chromosome STR loci (DYS19, DYS385, DYS389I and II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS460, DYS461, DYS635 [GATA C4], GATA H4, and GATA A10) were analyzed in a sample of 3,026 father/son pairs. Among 27,029 allele transfers, 54 mutations were observed, with an overall mutation rate across the 17 loci of 1.998 x 10(-3) (95% CI, 1.501 x 10(-3) to 2.606 x 10(-3)). With just one exception, all of the mutations were single-step, and they were observed only once per gametogenesis. Repeat gains were more frequent than losses, longer alleles were found to be more mutable, and the mutation rate seemed to increase with the father's age. Hum Mutat 26(6), 520-528, 2005. (c) 2005 Wiley-Liss, Inc.

Autosomal STR genetic variation in negroid Chocó and Bogotá populations

Genetic data for eight autosomal STRs were obtained from two different population samples from Colombia: the European Mestizo population of Bogotá and the African descent population of the Chocó region. The STRs were analysed in a multiplex system that includes the STR markers CSF1PO, TPOX, TH01, VWA, D13S317, D7S820, D16S539 and D5S818. Separation of the fragments and fluorescent detection was carried out in an ABI 310 DNA sequencer and the typing was made by comparison with sequenced allelic ladders. Exact tests were used for testing linkage between the loci and for Hardy-Weinberg equilibrium. Significant differences were found between both populations for all the loci.

Autosomal, mtDNA, and Y-chromosome diversity in Amerinds: pre- and post-Columbian patterns of gene flow in South America

To evaluate sex-specific differences in gene flow between Native American populations from South America and between those populations and recent immigrants to the New World, we examined the genetic diversity at uni- and biparental genetic markers of five Native American populations from Colombia and in published surveys from native South Americans. The Colombian populations were typed for five polymorphisms in mtDNA, five restriction sites in the beta-globin gene cluster, the DQA1 gene, and nine autosomal microsatellites. Elsewhere, we published results for seven Y-chromosome microsatellites in the same populations. Autosomal polymorphisms showed a mean G(ST) of 6.8%, in agreement with extensive classical marker studies of South American populations. MtDNA and Y-chromosome markers resulted in G(ST) values of 0.18 and 0.165, respectively. When only Y chromosomes of confirmed Amerind origin were used in the calculations (as defined by the presence of allele T at locus DYS199), G(ST) increased to 0.22. G(ST) values calculated from published data for other South American natives were 0.3 and 0.29 for mtDNA and Amerind Y chromosomes, respectively. The concordance of these estimates does not support an important difference in migration rates between the sexes throughout the history of South Amerinds. Admixture analysis of the Colombian populations suggests an asymmetric pattern of mating involving mostly immigrant men and native women.

[Multiple sclerosis: epidemiological-genetic studies in the population of Antioquia, Colombia. Disequilibrium of HLA DQ alpha]

INTRODUCTION AND OBJECTIVE

Discrimination and quantification of the environmental and genetic components involved in developing multiple sclerosis (MS) have not been made. In order to discriminate these components we have ascertained affected individuals by MS belonging to the Paisa community from Antioquia, Colombia, a state localized in the tropical area of South America, to detect eventual linkage disequilibrium to HLA, locus DQ alpha, which could demonstrate the relevance of the genetic component.

DEVELOPMENT

A contingence analysis among case-control HLA DQ alpha genotype distributions, by using Monte Carlo resampling method to solve small number sample, showed that there are significant differences between the two groups. We observe that HLA DQ alpha 1.1, 1.2 allele frequencies were higher in the cases than in the controls. Also, there was significant HLA DQ alpha 3 allele lower frequency (p < 0.05) in the cases than in the controls.

CONCLUSIONS

Similar results have been described in other Caucasian populations living in non tropical areas. Before results could indicate that the Caucasoid populations genetic component implied in the susceptibility to MS have remained in Paisa community, whether the environmental component, being meaningful to develop MS.

Multiple sclerosis: association to HLA DQalpha in a tropical population

Studies performed in subtropical populations have found significant association between the phenotype multiple sclerosis (MS) and the major histocompatibility complex (MHC). We present the results of a case-control study conducted on a tropical population (Antioquia, Colombia) in order to detect a possible association between MS and HLA DQalpha (HLA DQA1*) alleles. Forty chromosomes belonging to MS patients were compared to two sets of controls (40 and 910 chromosomes, respectively). The HLA DQA1*0101 and DQA1*0102 alleles were found in a significantly higher proportion among the cases than among the controls, whereas the HLA DQA1*0103 allele was found in a significantly lower proportion of the cases. These results suggest that the association of HLA DQA1*0101, DQA1*0102 and DQA1*0103 to the MS phenotype found in Caucasian subtropical populations remains in individuals with MS inhabiting the tropics. This finding could mean that the major genetic component associated to the MHC in subtropical populations is the same in the tropics.

Increased prevalence of cysticercosis and taeniasis among professional fried pork vendors and the general population of a village in the Peruvian highlands. Cysticercosis Working Group in Peru

Two different populations in Saylla, a Peruvian village near Cusco, known for chicharrones, a local pork dish, were surveyed by serology and stool examination to determine the prevalence and epidemiologic characteristics of Taenia solium infection. Group I (n=43), the chicharroneros, were members of families professionally devoted to the making and selling of chicharrones, and Group II (n=102) was a sample of the general population of the same village. Unlike people in Group I, general villagers only occasionally prepare or sell this food product, and then only to their neighbors or relatives. The prevalence of taeniasis was extremely high (8.6%) for the chicharroneros and 3% for the general villagers. Seroprevalence for cysticercosis by immunoblot was similarly high in both groups (23.3% and 23.8%, respectively). Being female, older than 30, and having daily contact with pork were factors strongly associated with a positive serologic result for cysticercosis in the chicharroneros, whereas males were more frequently seropositive in the general villagers group. Antibody reaction to more antigen bands in immunoblots and neurologic symptoms were more common among the chicharroneros. Also, in the general villagers group, seroprevalence increased with each exposure factor, ranging from 9.4% in individuals who did not raise pigs to 50% in the small subgroup that raised pigs, butchered their own animals, sold pork, and sold chicharrones, suggesting that these activities are related to increased risk for tapeworm or larval infection.

Cytoprotective activity in the gastric mucosa of rats exposed to carbon tetrachloride-induced liver injury

The present study was undertaken to evaluate the cytoprotective activity in the gastric mucosa of rats subjected to CCl4-induced liver injury. Response of gastric mucosa to absolute ethanol insult or acid (pylorus ligation) after CCl4 challenge was analyzed. Intraperitoneal administration of CCl4 increased plasma AST and ALT, but liver protein and glycogen levels were decreased; in addition, gastric acid secretion was significantly increased with respect to control animals (1541 +/- 266 vs. 629 +/- 25 mu eq H+; p < 0.001). Microscopical gastric erosions were observed in 3/10 animals after CCl4 challenge. Pylorus-ligated as well as CCl4-challenged rats developed increased susceptibility to gastric lesions, compared to control (lesion indices: 4.6 +/- 0.20 vs 2.8 +/- 0.13; p < 0.05), while showing increased resistance to absolute ethanol-induced gastric damage (30.4 +/- 11.2 vs 89.7 +/- 9.7 mm, p < 0.01). PGE2 levels in the gastric mucosa were not influenced by exposure to CCl4. Ultrastructural studies revealed the presence of continuous ethanol-resistant and apparently more adherent layer of mucus in CCl4-challenged animals. Morphological evaluation revealed an increase in Alcian blue-stained mucus. A dual condition of enhanced sensitivity to HCl with increased tolerance to ethanol was observed in gastric mucosa of CCl4-treated animals. These observations could be explained by the amount and/or composition of protective mucus layer in the gastric mucosa.

[Paternity analysis: experience in Colombia]

BACKGROUND

Cases of dubious paternity may be resolved analyzing appropriate genetic markers in them.

AIM

To report the experience of a Colombian University in resolving cases of dubious paternity.

SUBJECTS AND METHODS

Fourteen serologic and electrophoretic genetic markers, that had a high probability of exclusion were analyzed in 349 cases of uncertain paternity.

RESULTS

In 50 cases, paternity was excluded and in 34, paternity was attributed with a probability over 0.99. In 85 cases, the paternity index was between 19 and 100, that classifies paternity as probable and in 179 cases, the analysis was inconclusive.

CONCLUSIONS

These genetic markers may be useful in the first approach to a paternity in investigation.

[The federal health expenditure on the uninsured population: Mexico 1980-1995]

In the last fifteen years Mexico suffered several economic crisis which have negatively affected public expenditure in social welfare and, as a consequence, public expenditure in health. This paper discusses the relationship between the adjustment policies adopted to confront these crisis and public expenditure in health care for the non-insured population, as well as the regional distribution of this expenditure. In part one, the evolution of general public expenditure, public expenditure in social welfare, and public expenditure in health between 1980 and 1995 is described. In part two, the distribution of public health expenditure for the non-insured population among the five regions in which the country was divided by the National Health Survey II is discussed. The main conclusion of this paper is that, between 1980 and 1995, the public expenditure gaps that have existed for a long time in Mexico among regions remained unchanged. These gaps basically affect the southern states of the country, are not related to health needs, and may deepen in view of the new relative cuts in public expenditure in social welfare announced by the new administration.

Polymorphisms and phyletic relationships of the Paisa community from Antioquia (Colombia)

The allelic frequencies of 14 polymorphic loci were obtained for the Paisa community (Antioquia, Colombia) and compared with those of Caucasoids, Negroids and Amerindians as an approach to better understand its ancestral origin. Data pertaining to Caucasoids included Basques, Spaniards and Jews, historically assumed to be the ancestors of Paisas. These comparisons suggested that the Paisa community is a Caucasoid group with very low Amerindian or Negroid contributions. Spaniards or Basques and, to a lesser extent, Sephardims seem to have been their most probable ancestors.

Rh--plasma iron binding capacity association. New evidence

The relationship between Rh phenotypes and the total iron binding capacity (TIBC) of plasma was studied in a sample from Medellín, Colombia. In a previous report from Santiago, Chile, children carrying the C Rh specificity had a higher level of TIBC than those having the specificity. The same association was found in young people from Medellín.

Gastrotoxic activity and inhibitory effects on gastric mucosal PGE2 production with different non-steroidal anti-inflammatory drugs: modifications induced by pretreatment with zinc acexamate

Gastrotoxic activities of different non-steroidal anti-inflammatory drugs (NSAIDs) (diclofenac, indomethacin, ketoprofen, naproxen and piroxicam) administered per os were compared with their ability to inhibit gastric prostaglandin E2 (PGE2) synthesis in the rat. In a parallel study, effects of pretreatment with zinc acexamate (ZAC) were also assessed. NSAIDs invariably caused gastric mucosal damage and a decrease of PGE2 levels. A good correlation between the decrease of PGE2 levels and the index of gastric lesion (r = 0.41; p < 0.021) was observed when results obtained with the different NSAIDs were pooled. ZAC pretreatment significantly decreased the overall severity of lesions induced by NSAIDs. However, no correlation between gastric lesion index and depletion of PGE2 gastric levels was observed after treatment with ZAC (r = 0.012; p < 0.948). These data corroborate the hypothesis that preservation of the capability to synthesize endogenous PGs is of critical importance in the maintenance of gastric mucosal integrity. The gastroprotective action observed with ZAC involves alternative mechanisms other than modification of PGE2 levels.

Morphological study of gastric lesions developing in the rat under several damaging conditions: modifications induced by pretreatment with zinc acexamate

Lesions developing in the gastric mucosa of the rat after exposure to different gastric damaging agents (100 mg/kg aspirin, and 70% or 100% ethanol) were assessed by scanning electron microscopy. The severity of the lesions was quantified according to morphological criteria. Modifications in the severity of these lesions induced by pretreatment with zinc acexamate were also analyzed. The scanning electron microscope revealed that with the exception of absolute ethanol, which caused distinctive morphological features, lesions found under the different experimental agents shared a common pattern of progression. Ultrastructural lesions on surface epithelial cells preceded further alterations of parietal cells. After the integrity of the epithelial cells was lost, detachment of the parietal cells occurred, probably, through peptic digestion of the connections between cells and their extracellular matrices. Pretreatment of animals with zinc acexamate increased the presence of mucus on the gastric surface and significantly prevented the progression of lesions towards the severest stages. Ultrastructural damage of surface epithelial cells was not influenced by this treatment, but detachment of damaged cells was clearly diminished. These data confirm the protective effect of zinc acexamate against gastric aggressions. Moreover, our studies confirm the notion that mucus secretion and maintenance of continuity on the gastric lumen by surface epithelial cells is of critical importance in preventing the gastric damage induced in these experimental models.

Experimental reactivation of chronic gastric lesions exposed to different aggressive conditions

Experimental reactivation of chronic gastric lesions induced by acetic acid injection to the rat stomach was produced after exposure of the animals to different secondary damaging conditions. On day 18 after the initial injury, animals (n = 100) were distributed in five groups. One of them was used as control and the remainder were subjected to absolute ethanol, stress, pyloric ligation or aspirin. Measurements of gastric acid secretion were performed. Pyloric ligation resulted in the maximal rate of acid secretion. Computerized morphometric analysis of the gastric injuries showed a significant association (70%, p less than 0.01) of hemorrhagic lesions with the primary site of chronic injury in animals subjected to pyloric ligation. No significant association was observed after absolute ethanol (30%), aspirin (30%) or stress (35%). The presence of hemorrhage associated with the original gastric lesions was more dependent on the disorganization of the lamina propria and proliferation of chief cells in the margins of the mucosal scar than on the severity of extent of the chronic lesions. These results indicate that local conditions at the level of gastric mucosa together with an increased presence of acid in the gastric lumen provide favorable conditions for the reactivation of primary chronic lesions in the rat.

Arthritis mutilans, tumoral calcinosis, Raynaud's phenomenon and Sjögren's syndrome

We report a female patient who over 25 years developed a progressive deforming arthropathy involving both hands without anatomical or functional abnormalities of other joints. Raynaud's phenomenon, lung fibrosis and Sjögren's syndrome. She had multiple soft tissue and periarticular calcification particularly evident in the lower extremities, shoulders, hands, fingers and back.

Effect of zinc acexamate and ranitidine on chronic gastric lesions in the rat

Using the rat as an experimental model we have studied the healing of chronic gastric lesions and the modifications of these lesions by antiulcer agents. Gastric injuries were induced by submucosal injection of 0.05 ml of 5% acetic acid. Placebo, ranitidine (RNT) or zinc acexamate (ZAC) were administered orally. The evolution of gastric injuries was macro- and microscopically evaluated at 6, 12 and 21 days after acetic acid injection. The administration of either RNT (30 mg/kg) or ZAC (200 mg/kg) was followed by a marked improvement of the healing process with respect to control groups. The size of experimental ulcers at 21 days was 3.1 +/- 0.8 mm2 for the control group, 1.8 +/- 1.1 mm2 for RNT-treated animals and 0.3 +/- 0.6 mm2 for ZAC-treated rats (p less than 0.05, vs. control). A similar tendency was observed when lesions were microscopically analyzed. Indices of microscopical lesions (0-6) at 21 days were 3.8 +/- 0.8 for the control group, 3.0 +/- 0.8 for rats receiving RNT and 2.3 +/- 0.4 for rats receiving ZAC (p less than 0.05, vs. control). The statistical analysis of the distribution of microscopical indices of lesions showed significant differences in favour of ZAC at days 6 (p less than 0.01) and 21 (p less than 0.05). Our study indicates that the evolution of gastric damage induced by acid acetic injection was consistently better in rats treated with ZAC than in those receiving RNT. Data obtained in our experiments suggest that the blockade of H2 receptors does not guarantee the optimal healing of chronic gastric lesions induced in rats.

Development of a simple embedding procedure allowing immunocytochemical localization at the ultrastructural level

Immunobed solution A is a water-soluble acrylic compound recently developed for immunocytochemical localization at the light microscopic level. In this study, we combined it with methyl methacrylate (MMA) to achieve sufficient hardness to obtain ultra-thin sections. Samples of platelets were dehydrated and embedded in the water-soluble acrylic mixture (WSAM). The embedding process was carried out at 4 degrees C and final polymerization was induced with either chemical (benzoyl peroxide) or physical (UV light) catalysts. Tubulin was localized at the ultrastructural level in sections embedded according to these two methods. Results were compared with those obtained in platelets processed in Lowicryl. Dehydration and embedding with the WSAM yielded a preservation of antigenicity similar to that obtained in Lowicryl. The new procedure benefits from the low temperature achieved during polymerization, providing good ultrastructural morphology and immunolocalization of protein antigens with the simplicity of a routine embedding procedure for light microscopy.

Evaluation of cutaneous absorption and safety of idoxuridine after topical administration

The absorption of a preparation of the antiviral drug 5-iodo-2'-deoxyuridine (idoxuridine or IDU] has been assessed in rats. A 40% w/v solution of 3H-IDU in dimethyl sulfoxide (DMSO) was topically applied to rats; cutaneous absorption was determined by morphometric evaluation of autoradiographic preparations of the skin. Passage of the drug to the bloodstream was followed using radioisotopic techniques. In addition, the potential irritative action of the same preparation of IDU was investigated in a more suitable animal model. A predictive guinea pig sensitization study was performed according to the Magnusson and Kligman method. 3H-IDU was detected in the epidermis of the rat 60 min after local application. However, it was not possible to determine noticeable levels of the radiolabelled drug in the circulating blood. Experiments on guinea pigs showed slight transient erythematous responses in three animals of the test group following first challenge, and in one animal of the test group and one of the control group, following the second challenge. The overall results of the sensitization test were negative. These results give experimental support for the safety of the IDU preparation studied.

Immunogold staining of microtubules in resting and activated platelets

A circumferential microtubule is known to support the discoid form of resting platelets, but its fate following exposure of the cells to aggregating agents is uncertain. The present study has employed an immunocytochemical approach to follow the fate of the circumferential microtubule in activated platelets. Monoclonal antibodies to tubulin and to vinculin and a polyclonal antibody to actin were incubated with isolated microtubule coils and stained with staphylococcal protein A coupled to immunogold in order to test their specificity. Thin sections of glycolmethacrylate embedded platelets before and after exposure to thrombin for 15, 30 and 60 s were stained with antibodies to tubulin and actin. Immunogold particles showed a high specificity for isolated MT coils stained for tubulin, modest intensity for actin, and none for vinculin. Gold particles were randomly distributed in thin sections of resting and activated platelets stained for actin. Immunogold was limited to the circumferential microtubule in resting platelets and constricted coils in thrombin-activated cells. The number of gold particles in areas of cytoplasm away from microtubules in platelets stained with antitubulin antibody increased slightly following thrombin activation, but the change was not significant. Results support the concept that microtubule coils supporting the discoid form of resting platelets do not dissolve following exposure of the cells to potent agonists.

Interaction of long-term stored platelets with vascular subendothelium

Platelets stored as platelet-rich plasma under mildly alkaline conditions in vitro maintain morphologic integrity and functional capability for 2 to 3 weeks. We used the Baumgartner method to assess the ability of long-term stored platelets to interact with exposed vascular subendothelium. After 3 days in storage the size and number of thrombi on damaged surfaces decreased. However, the percentage of vascular surface covered was not reduced significantly until the cells had been stored for 14 days. Treatment of vascular segments with chymotrypsin to increase thrombogenicity caused platelets stored for 14 days to adhere and form aggregates on denuded surfaces in a manner similar to that of fresh platelets, but the ability to develop thrombi remained depressed. Thus long-term storage that maintains physical and functional integrity also preserves a reasonable capacity of platelets to interact with damaged blood vessels.