First record of larval microhabitats of sandflies in Mexico with the description of the fourth instar larva of Brumptomyia hamata.

Despite the medical importance of sandflies as vectors (Diptera: Phlebotominae) of Leishmania spp., immature stages of phlebotomine sandflies have never been found in the wild in Mexico. In the present investigation, we sought to identify specific microhabitats associated with the presence of sandfly immature stages. Field work was conducted in 11 localities of the Yucatan Peninsula and we collected soil samples from each site during two periods (November 2007 to April 2008, November 2008). Soil samples were transported to our base camp and were processed using the Berlese's funnels. We processed a total 242 soil samples with an average weight of 362 ± (SD) 317 gr. From these samples, we were able to recover 51 phlebotomine larvae in five different microhabitats and largest number was obtained from mammal burrows (88%) and from tree-buttresses of Brosimium alicastrum (Berg) (6%). We identified larval microhabitat for Brumptomyia hamata (Fairchild & Hertig) and those specimens provided the material to describe for the first time the fourth instar larva. We also include information of a larval microhabitat of Lutzomyia cruciata (Coquillett). In addition, we recorded a total of 4872 arthropods from 15 taxa in all those soil samples in which sandfly larvae were found, being Collembola (76%) and Acari (10%) the most abundant.

Histidine Self-assembly and Stability on Mineral Surfaces as a Model of Prebiotic Chemical Evolution: An Experimental and Computational Approach.

The abiotic synthesis of histidine under experimental prebiotic conditions has proven to be chemically promising and plausible. Within this context, the present results suggest that histidine amino acid may function as a simple prebiotic catalyst able to enhance amino acid polymerization. This work describes an experimental and computational approach to the self-assembly and stabilization of DL-histidine on mineral surfaces using antigorite ((Mg, Fe)3Si2O5(OH)4), pyrite (FeS2), and aragonite (CaCO3) as representative minerals of prebiotic scenarios, such as meteorites, and subaerial and submarine hydrothermal systems. Experimental results were obtained through polarized-light microscopy, IR spectroscopy (ATR-FTIR), and differential scanning calorimetry (DSC). Molecular dynamics was performed through computational simulations with the MM + method in HyperChem software. IR spectra suggest the presence of peptide bonds in the antigorite-histidine and aragonite-histidine assemblages with the presence of amide I and amide II vibration bands. The FTIR second derivative inspection supports this observation. Moreover, DSC data shows histidine stabilization in the presence of antigorite and aragonite by changes in histidine thermodynamic properties, particularly an increase in histidine decomposition temperature (272ºC in antigorite and 275ºC in aragonite). Results from molecular dynamics are consistent with DSC data, suggesting an antigorite-histidine closer interaction with decreased molecular distances (cca. 5.5 Å) between the amino acid and the crystal surface. On the whole, the experimental and computational outcomes support the role of mineral surfaces in prebiotic chemical evolution as enhancers of organic stability.

Prevalence and distribution of hepatitis C virus genotypes in Spain during the 2000-2015 period (the GEHEP 005 study).

We report the largest study on the prevalence and distribution of HCV genotypes in Spain (2000-2015), and we relate them with clinical, epidemiological and virological factors. Patients from 29 hospitals in 10 autonomous communities (Andalusia, Aragon, Castilla-Leon, Catalonia, Galicia, Canary Islands, Madrid Community, Valencian Community, Murcia Region and Basque Country) have been studied. Annual distribution of HCV genotypes and subtypes, as well as gender, age, transmission route, HIV and/or HBV coinfection, and treatment details were recorded. We included 48595 chronically HCV-infected patients with the following characteristics: median age 51 years (IQR, 44-58), 67.9% male, 19.1% HIV-coinfected, 23.5% HBV-coinfected. Parenteral transmission route was the most frequent (58.7%). Genotype distribution was 66.9% GT1 (24.9% subtype 1a and 37.9% subtype 1b), 2.8% GT2, 17.3% GT3, 11.4% GT4 and 0.1% GT5 and 0.02% GT6. LiPA was the most widely HCV genotyping test used (52.4%). HCV subtype 1a and genotypes 3 and 4 were closely associated with male gender, parenteral route of infection and HIV and HBV coinfection; in contrast, subtype 1b and genotype 2 were associated with female gender, nonparenteral route and mono-infection. Age was related to genotype distribution, and different patterns of distribution and biodiversity index were observed between different geographical areas. Finally, we describe how treatment and changes in transmission routes may have affected HCV genotype prevalence and distribution patterns. We present the most recent data on molecular epidemiology of hepatitis C virus in Spain. This study confirms that genotype distributions vary with age, sex, HIV and HBV coinfection and within geographical areas and epidemiological groups.

Reduced Meloidogyne ethiopica Parasitism in Vitis vinifera Grafted on Six Resistant Rootstocks Under Field and Greenhouse Conditions.

Meloidogyne ethiopica, an aggressive nematode, causes significant economic losses to Vitis crops. Rootstocks can successfully manage phytoparasitic nematodes. However, no studies exist on M. ethiopica-resistant rootstocks under field conditions. This study assessed the resistance of six Vitis rootstocks to M. ethiopica under field and greenhouse conditions. The number of galls and eggs in vine roots, quantity of second stage juveniles and males in 250 ml of soil, root weight, and shoot weight were determined for the Harmony, SO4, 101-14 MG, 110R, 3309C, and Kober 5BB rootstocks, and the own-root Chardonnay variety as a control. In the field, Harmony, SO4, 101-14 MG, Kober 5BB, and 110R were highly resistant to nematode parasitism and reproduction. In turn, 3309C was the least resistant rootstock. In the greenhouse, all rootstocks similarly limited M. ethiopica attack and reproduction. In both conditions, Chardonnay was the most susceptible vine to nematode attack, with high quantities of galls, eggs, and nematode reproduction. In conclusion, most of the evaluated rootstocks reduced M. ethiopica parasitism. Harmony, SO4, 101-14 MG, 110R, and Kober 5BB rootstocks are options for vineyard use, with final selection dependent on winegrower requirements.

Differential characteristics of healthcare-associated compared to community-acquired febrile urinary tract infections in males.

The objective of this study was to analyse the characteristics of healthcare-associated febrile urinary tract infection (HCA-FUTI) compared to community-acquired FUTI (CA-FUTI) in men. An ambispective cross-sectional study in which we recorded clinical and microbiology data and outcomes from males with FUTI attended in the Emergency Department was carried out. A total of 479 males with FUTI, 162 (33.8%) HCA-FUTI and 317 (66.2%) CA-FUTI, were included. HCA-FUTI patients were older (p < 0.001), had higher Charlson scores (p < 0.001) and received previous antimicrobial treatment more frequently (p < 0.001) compared to CA-FUTI patients. HCA-FUTI was less likely caused by Escherichia coli (p < 0.001) and more frequently by Klebsiella spp. (p = 0.02), Enterobacter spp. (p < 0.001) and Pseudomonas aeruginosa (p < 0.001). Resistance to ceftriaxone (p = 0.006), gentamicin (p < 0.001), quinolones (p < 0.001), co-trimoxazole (p = 0.001) and fosfomycin (p = 0.009) was higher among E. coli strains isolated from males with HCA-FUTI and so was the prevalence of extended-spectrum beta-lactamase and AmpC E. coli and Klebsiella spp.-producing strains (p = 0.012). Inadequate antimicrobial treatment and all-cause in-hospital mortality was associated with HCA-FUTI (p < 0.001 and p = 0.004, respectively). Independent factors for mortality were severe sepsis or septic shock [odds ratio (OR) 29; 95% confidence interval (CI): 3.9-214] and cirrhosis (OR 23.7; 95% CI: 1.6-350.6). Male patients with HCA-FUTI have different clinical characteristics, outcomes and microbiological features compared to CA-FUTI patients. Previous contact with the healthcare system has to be taken into consideration when deciding the optimal antimicrobial treatment in males with FUTI.

Improving detection and genetic counseling in carriers of spinal muscular atrophy with two copies of the SMN1 gene.

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by mutations in the survival motor neuron1 gene (SMN1). Global carrier frequency is around 1 in 50 and carrier detection is crucial to define couples at risk to have SMA offspring. Most SMA carriers have one SMN1 copy and are currently detected using quantitative methods. A few, however, have two SMN1 genes in cis (2/0 carriers), complicating carrier diagnosis in SMA. We analyzed our experience in detecting 2/0 carriers from a cohort of 1562 individuals, including SMA parents, SMA relatives, and unrelated individuals of the general population. Interestingly, in three couples who had an SMA child, both the parents had two SMN1 copies. Families of this type have not been previously reported. Our results emphasize the importance of performing a detailed carrier study in SMA parents with two SMN1 copies. Expanding the analysis to other key family members might confirm potential 2/0 carriers. Finally, when a partner of a known carrier presents two SMN1 copies, the study of both parents will provide a more accurate diagnosis, thus optimizing genetic counseling.

Minimum spread of the new Swedish variant of Chlamydia trachomatis and distribution of C. trachomatis ompA genotypes in three geographically distant areas of Spain, 2011-2012.

PURPOSE: The aim of this study was to determine the presence of the new Swedish Chlamydia trachomatis (C. trachomatis) variant (nvCT) and the distribution of C. trachomatis ompA genotypes in three geographically distant regions of Spain. METHODS: The genotypes of strains causing 624 episodes of infection (January 2011-September 2012) were studied using a nested PCR that amplifies a fragment of the ompA gene, followed by sequencing. To detect nvCT, a real-time PCR was used that amplifies a fragment of the cryptic plasmid with a 377 base pair deletion, which identifies the nvCT. RESULTS AND CONCLUSION: The ompA genotype was identified in 565 (90.5%) episodes. Eleven genotypes were detected, of which nine were found in all three regions. Only one nvCT strain was detected (0.4%), despite the predominance of genotype E (41%). Other frequent genotypes were genotypes D (19%), F (13%), G (11 %), and J (7%). Genotype L2b, causing lymphogranuloma venereum, was detected in men who have sex with men (MSM) in all three regions. Genotypes E and F were more frequent in women and heterosexual men, and genotypes D, G, J and L2b in MSM. In men, the main factor causing differences in the distribution of C. trachomatis was sexual behavior (MSM versus heterosexual men), while the distribution of C. trachomatis genotypes was similar in women and heterosexual men.

Acquired perforating dermatosis: a report of 8 cases.

Acquired perforating dermatosis (APD) is an uncommon disease characterized by lesions exhibiting transepidermal elimination of collagen or elastic fibers. APD affects adults and is associated with systemic diseases, mainly diabetes mellitus and renal failure. We present 8 cases of APD. Seven patients had concomitant diabetes mellitus with or without chronic renal failure, and 1 had alcoholic cirrhosis. In the patients with chronic renal failure, the onset of APD coincided with transient worsening of renal function. The mean increase in creatinine concentrations above baseline was 1.14mg/dL. Acute deterioration of renal function may be involved in APD. Further studies are needed to investigate this association.

Photosensitivity due to thiazides.

Thiazides are widely used diuretics that first became available in the 1950s. The first reports of photosensitivity reactions to thiazides were published shortly after the introduction of these drugs, but few cases have been described since. We review all the cases of photosensitivity due to thiazides published up to December 2011. We found 62 cases, 33 in women and 29 in men. The most common presentation was eczematous lesions in a photodistributed pattern, and the most common causative agent was hydrochlorothiazide. The results of photobiological studies were published in only some of the cases reviewed. In most cases, phototesting revealed an abnormal response to UV-A alone or to both UV-A and UV-B. In some cases, the results of phototesting were normal and only photopatch testing yielded abnormal results. Diagnosis of photosensitivity due to thiazides requires a high degree of suspicion. Ideally, diagnosis should be confirmed by a photobiological study.

Late effects of Wilms' tumor treatment. / Efectos tardíos del tratamiento del tumor de Wilms.

INTRODUCTION: Wilms' tumor (WT) is the most frequent renal tumor in childhood. Therapeutic management progression has increased survival rates, and as a result, long-term adverse effects. MATERIALS AND METHODS: A descriptive retrospective study of a case series from 1977 to 2023 was carried out. The characteristics of the treatments received and the adverse effects listed on medical records were analyzed via phone surveys. RESULTS: 50 patients (25 boys-25 girls) with a mean age of 3.6 years (3 months-11 years) at diagnosis were included. Most of them (94%) were treated according to the protocol established by the European standards of pediatric oncology, which are characterized by the use of neoadjuvant chemotherapy. In one patient, the American treatment scheme was followed. The most common drugs used were vincristine and actinomycin D (78%). Only 12 patients (28%) received anthracyclines. Unilateral nephrectomy was the most frequent surgical technique (84%). Renal disorders were the most common (46%). However, the occurrence of second neoplasias (9%) and reproductive disorders (8% between boys and girls) had a greater impact on patients' quality of life. Multiple - cardiac (23%), endocrine (26%), and pulmonary (15%) - disorders associated with the treatments received were reported. CONCLUSIONS: WT treatment has an impact on health. Adequate and rigorous surgery, close follow-up, and limiting chemotherapy doses and radiation exposure can minimize long-term sequels.

INTRODUCCION: El tumor de Wilms (TW) es el tumor renal más frecuente en la infancia. La evolución del manejo terapéutico ha incrementado la tasa de supervivencia y como consecuencia, los efectos secundarios a largo plazo. MATERIAL Y METODOS: Realizamos un estudio retrospectivo descriptivo a partir de una serie de casos entre 1977 y 2023. Estudiamos las características de los tratamientos recibidos y los efectos secundarios que constan en su historia clínica y a través de cuestionarios telefónicos. RESULTADOS: Localizamos 50 pacientes (25 hombres-25 mujeres) con edad media al diagnóstico de 3,6 años (3 meses-11 años). La mayoría fueron tratados según protocolo vigente de las guías europeas de oncología pediátrica (94%) caracterizadas por el uso de quimioterapia neoadyuvante. En un paciente Se siguió el esquema americano de tratamiento. Los fármacos más utilizados fueron vincristina y actinomicina D (78%); solo 12 pacientes (28%) recibieron antraciclinas. La nefrectomía unilateral fue la técnica quirúrgica más empleada (84%). Las alteraciones renales fueron las más frecuentes (46%). Sin embargo, la aparición de segundas neoplasias (9%) y aquellas alteraciones relacionadas con la reproducción (8% entre hombres y mujeres) suponen un mayor impacto en la calidad de vida de los pacientes. Se describen múltiples alteraciones: cardíacas (23%), endocrinas (26%) o pulmonares (15%) relacionadas con los tratamientos recibidos. CONCLUSIONES: El tratamiento del TW afecta a la salud general. Una cirugía adecuada y rigurosa, limitar las dosis de quimioterapia, minimizar la exposición a la radiación y un seguimiento estrecho puede minimizar las secuelas a largo plazo.

Psoriasis, psoriatic arthritis and type 2 diabetes mellitus: a systematic review and meta-analysis.

Several observational studies have assessed the association between psoriasis, psoriatic arthritis (PsA) and type 2 diabetes mellitus, with inconclusive results. We set out to investigate the association between psoriasis, PsA and type 2 diabetes mellitus. Observational studies assessing the relationship between psoriasis or PsA and type 2 diabetes mellitus up to December 2012 were identified by electronic and hand searches in Medline, Embase, PubMed, the Cochrane Database of Systematic Reviews and Google Scholar. For each study we collected the first author's last name, publication year, country of origin, study design, characteristics of participants (sample size, age and sex), the variables incorporated into the multivariable analyses, and the odds ratios (ORs) of psoriasis associated with diabetes along with the corresponding 95% confidence intervals (CIs). From the data provided in each article, the crude OR was also calculated. Forty-four observational studies (in 37 articles) were identified for the final analysis. The pooled OR from random-effects analysis was determined to be 1·76 (95% CI 1·59-1·96). The highest risk was for patients suffering from PsA (OR 2·18, 95% CI 1·36-3·50). We also observed a dose effect in the risk of suffering from type 2 diabetes mellitus, as patients considered as having severe psoriasis had higher risk (OR 2·10, 95% CI 1·73-2·55) than the pooled OR. We perform meta-regression and sensitivity analyses to explore sources of heterogeneity among the studies and to determine how they would influence the estimates, and found no significant influence in the results of the meta-analyses. The findings support the association between psoriasis, PsA and type 2 diabetes mellitus. Some caution must be taken in the interpretation of these results because there may be heterogeneity between studies.

Photodistributed erythema multiforme.

Although the existence of photodistributed erythema multiforme has been recognized for years, few cases have been described to date. It is an uncommon, and probably underdiagnosed, skin disorder that can affect individuals of both sexes and all ages. It has been associated with drugs, reactivation of herpes simplex virus infection, and polymorphous light eruption. A diagnosis is made on the basis of history, physical examination, histology, and phototesting. The condition runs a benign, self-limiting course but patients may experience outbreaks for several years if the causative agent is not eliminated. It is treated symptomatically and patients are advised to avoid triggers and excessive sun exposure.

Intestinal intussusception in adults: Location, causes, symptoms, and therapeutic management.

OBJECTIVE: Intestinal intussusception is difficult to diagnose in adults because the symptoms are nonspecific. However, most have structural causes that require surgical treatment. This paper reviews the epidemiologic characteristics, imaging findings, and therapeutic management of intussusception in adults. MATERIALS AND METHODS: This retrospective study identified patients diagnosed with intestinal intussusception who required admission to our hospital between 2016 and 2020. Of the 73 cases identified, 6 were excluded due to coding errors and 46 were excluded because the patients were aged <16 years. Thus, 21 cases in adults (mean age, 57 years) were analyzed. RESULTS: The most common clinical manifestation was abdominal pain, reported in 8 (38%) cases. In CT studies, the target sign yielded 100% sensitivity. The most common site of intussusception was the ileocecal region, reported in 8 (38%) patients. A structural cause was identified in 18 (85.7%) patients, and 17 (81%) patients required surgery. The pathology findings were concordant with the CT findings in 94.1% of cases; tumours were the most frequent cause (6 (35.3%) benign and 9 (64.7%) malignant). CONCLUSIONS: CT is the first-choice test for the diagnosis of intussusception and plays a crucial role in determining its aetiology and therapeutic management.

Gamma irradiation of adenine and guanine adsorbed into hectorite and attapulgite.

This study focuses on the radiolysis (up to 36 kGy) of guanine and adenine (nitrogenous bases) adsorbed in hectorite and attapulgite to highlight the potential role of clays as protective agents against ionizing radiation in prebiotic processes. In this framework, the study investigated the nitrogenous bases' behavior in two types of systems: a) aqueous suspension of adenine-clay systems and b) guanine-clay systems in the solid state. This research utilized spectroscopic and chromatographic techniques for its analytical purposes. Regardless of the reaction medium conditions, the results reveal that nitrogenous bases are stable under ionizing irradiation when adsorbed on both clays.

Effect of recombinant growth hormone on leptin, adiponectin, resistin, interleukin-6, tumor necrosis factor-α and ghrelin levels in growth hormone-deficient children.

BACKGROUND: Treatment with GH promotes linear growth and decreases body fat in patients with isolated GH deficiency (GHD). However, few studies have analyzed how GH replacement modifies ghrelin levels and the adipokine profile and the relationship of these modifications with the metabolic changes. AIMS: To analyze the eventual differences between serum levels of leptin, leptin soluble receptor (sOBR), resistin, adiponectin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total (TG) and acylated ghrelin (AG) and lipid and glycemic profiles in children with GHD, as well as to determine the effect of GH replacement on these parameters during the first year of therapy. SUBJECTS AND METHODS: Thirty pre-pubertal (Tanner stage I) GHD children and 30 matched controls were enrolled. Children with GHD were studied before and after 6 and 12 months of GH treatment. Weight, height, BMI, fasting glucose, insulin, lipid profile and serum levels of adipokines and ghrelin were studied at every visit. Adi - pokines, insulin and ghrelin levels were determined by using commercial radio- and enzymoimmunoassays. RESULTS: At baseline children with GHD had significantly higher sOBR (p<0.01) and adiponectin (p<0.01) levels than controls. Treatment with GH resulted in a decline in leptin (p<0.05) and TG (p<0.001) levels, an increase of homeostasis model assessment index and restored IGF-I levels (p<0.001). CONCLUSIONS: These data indicate that GH replacement has a negative effect on leptin levels and may also produce a slight unfavorable effect on carbohydrate metabolism. In addition, the changes observed in the adipokine profile appear to be independent of body mass index.

The c.859G>C variant in the SMN2 gene is associated with types II and III SMA and originates from a common ancestor.

Homozygous mutations of the telomeric SMN1 gene lead to degeneration of motor neurons causing spinal muscular atrophy (SMA). A highly similar centromeric gene (SMN2) can only partially compensate for SMN1 deficiency. The c.859G>C variant in SMN2 has been recently reported as a positive disease modifier. We identified the variant in 10 unrelated chronic SMA patients with a wide spectrum of phenotypes ranging from type II patients who can only sit to adult walkers. Haplotype analysis strongly suggests that the variant originated from a common ancestor. Our results confirm that the c.859G>C variant is a milder SMN2 allele and predict a direct correlation between SMN activity and phenotypic severity.

Intestinal intussusception in adults: location, causes, symptoms, and therapeutic management. / Invaginaciones intestinales en el adulto: localización, etiología, sintomatología y manejo terapéutico.

OBJECTIVE: Intestinal intussusception is difficult to diagnose in adults because the symptoms are nonspecific. However, most have structural causes that require surgical treatment. This paper reviews the epidemiologic characteristics, imaging findings, and therapeutic management of intussusception in adults. MATERIALS AND METHODS: This retrospective study identified patients diagnosed with intestinal intussusception who required admission to our hospital between 2016 and 2020. Of the 73 cases identified, 6 were excluded due to coding errors and 46 were excluded because the patients were aged<16 years. Thus, 21 cases in adults (mean age, 57 y) were analyzed. RESULTS: The most common clinical manifestation was abdominal pain, reported in 8 (38%) cases. In CT studies, the target sign yielded 100% sensitivity. The most common site of intussusception was the ileocecal region, reported in 8 (38%) patients. A structural cause was identified in 18 (85.7%) patients, and 17 (81%) patients required surgery. The pathology findings were concordant with the CT findings in 94.1% of cases; tumors were the most frequent cause (6 (35.3%) benign and 9 (64.7%) malignant). CONCLUSIONS: CT is the first-choice test for the diagnosis of intussusception and plays a crucial role in determining its etiology and therapeutic management.

Neonatal and adult gonadal hormone manipulations enhance morphine analgesia elicited from the ventrolateral periaqueductal gray in female rats.

Male rodents displayed greater magnitudes of analgesia following systemic, ventricular, and intracerebral administration of mu-opioid receptor agonists than female rodents. Whereas neonatal castration of male rat pups produced reductions in systemic and central morphine analgesia as adults, neonatal androgenization of female rat pups treated with testosterone propionate (TP) displayed enhancements in systemic and central morphine analgesia as adults. Adult gonadectomy minimally affected mu-opioid analgesia, except if less potent mu agonists were employed, or if morphine was directly administered into the ventrolateral periaqueductal gray (vlPAG). Adult ovariectomy failed to appreciably alter the enhanced analgesia following systemic morphine in female rats with neonatal androgenization. Because the vlPAG elicited morphine analgesia that was sensitive to both neonatal and adult gonadal hormone manipulations, the present study examined morphine analgesia elicited from the vlPAG in female rats receiving neonatal treatment with TP or vehicle and subsequently exposed to adult ovariectomy or sham surgery as well as intact male rats. Intact male rats displayed significantly greater magnitudes and potencies in vlPAG morphine analgesia than female rats receiving neonatal treatment with either vehicle or TP. In turn, neonatal androgenization significantly enhanced vlPAG morphine analgesia relative to neonatal vehicle treatment in females. Adult ovariectomy significantly enhanced the magnitude of vlPAG morphine analgesia in female rats receiving neonatal treatment with either vehicle or TP. This demonstrates a strong interaction between neonatal and adult gonadal hormone manipulations in the mediation of vlPAG morphine analgesia in female rats.

Anticarcinoma activity in vivo of rhodamine 123, a mitochondrial-specific dye.

Carcinoma cells and normal epithelial cells differ in the mitochondrial retention of a permeant cationic compound, rhodamine 123. The possibility of utilizing this difference in carcinoma chemotherapy was investigated. Rhodamine 123 exhibited anticarcinoma activity in mice, and this activity was potentiated by 2-deoxyglucose.

Rhodamine-123 selectively reduces clonal growth of carcinoma cells in vitro.

Rhodamine-123, a cationic laser dye, markedly reduced the clonal growth of carcinoma cells but had little effect on nontumorigenic epithelial cells in vitro. This selective inhibitory effect of Rhodamine-123 on some carcinomas is unusual since known anticancer drugs, such as arabinosyl cytosine and methotrexate, have not been shown to exhibit such selectivity in vitro.