Biomedical subjects

Javier Nieto

Publications and source records attributed to Javier Nieto.

14 recordsLinked to original sources

PubMed2006

Diastereoselective synthesis of enantiopure morpholines by electrophilic selenium-induced 6-exo cyclizations on chiral 3-allyl-2-hydroxymethylperhydro-1,3-benzoxazine derivatives.

Enantiopure morpholine derivatives have been prepared by selenocyclofunctionalization of chiral 3-allyl-2-hydroxymethyl-substituted perhydro-1,3-benzoxazine derivatives. The cyclization occurs in high yields and diastereoselection, although the temperature of the reaction and the structure of the substituent at C-2 and the substitution pattern of the double bond can modify the regio- and stereochemistry of the final products.

Journal Article↗

PubMed2006

1,4-asymmetric induction in methoxyselenenylation of double bonds at the nitrogen side of chiral perhydro-1,3-benzoxazines promoted by nonbonded Se...N interactions.

Regio- and diastereoselective methoxyselenenylation of cinnamylamines attached to a chiral perhydrobenzoxazine occurs in high yields by reaction with benzeneselenenyl chloride in dichloromethane-methanol. The diastereoselection is dependent on the temperature of the reaction and the structure of the substituent at C-2 and can be rationalized by accepting a 1,4-asymmetric induction process after coordination of the selenium to the nitrogen atom of the allylamine system.

Benzoxazines↗

PubMed2006

Regio- and stereoselective methoxyselenenylation of chiral 2-vinyl perhydro-1,3-benzoxazines promoted by selenium-heteroatom nonbonded interactions.

Regio- and diastereoselective methoxyselenenylations of double bonds attached to the N,O-ketalic carbon of chiral perhydrobenzoxazines occur in high yields by reaction with benzeneselenenyl chloride in dichloromethane-methanol. The diastereoselection is dependent on the reaction conditions and the structure of the starting compounds and can be rationalized by accepting the coordination of the selenium to the oxygen atom of the heterocycle.

Benzoxazines↗

PubMed2006

Should we perform an echocardiogram in hypertensive patients classified as having low and medium risk?

BACKGROUND: Left ventricular hypertrophy is an important predictor of cardiovascular risk and its detection contributes to risk stratification. However, echocardiography is not a routine procedure and electrocardiography (ECG) underestimates its prevalence. OBJECTIVE: To evaluate the prevalence of echocardiographic left ventricular hypertrophy in low and medium risk non-treated hypertensive subjects, in order to find out the percentage of them who would be reclassified as high risk patients. METHODS: Cross-sectional, multicenter study was performed in hospital located hypertension units. An echocardiogram was performed in 197 previously untreated hypertensive patients, > 18 years, classified as having low (61%) or medium (39%) risk, according to the OMS/ISH classification. The presence of left ventricular hypertrophy was considered if left ventricular mass index was > or = 134 or 110 g/m(2) in men and women, respectively (Devereux criteria). A logistic regression analysis was performed to identify factors associated to left ventricular hypertrophy. RESULTS: The prevalence of left ventricular hypertrophy was 23.9% (95% CI:17.9-29.9), 25.6% in men and 22.6% in women. In the low risk group its prevalence was 20.7% and in medium risk group 29.5%. Factors associated to left ventricular hypertrophy were: years since the diagnosis of hypertension, OR:1.1 (95% CI:1.003-1.227); systolic blood pressure, OR:1.08 (95% CI:1.029-1.138); diastolic blood pressure, OR:0.9 (95% CI:0.882-0.991); and family history of cardiovascular disease, OR:4.3 (95% CI:1.52-12.18). CONCLUSIONS: These findings underline the importance of performing an echocardiogram in low and high risk untreated hypertensive patients in which treatment would otherwise be delayed for even one year.

Adult↗

PubMed2006

Comparison of new diagnostic tools for management of pediatric Mediterranean visceral leishmaniasis.

New techniques are available for diagnosing leishmaniasis, but their efficacy in the identification of pediatric visceral leishmaniasis (VL) has not been compared with that of traditional methods. Blood, bone marrow, and urine samples were taken from 25 children with VL during their first clinical episode, 22 days after the start of treatment with liposomal amphotericin B (3 mg/kg/day on 6 days over a 10-day period), and when a relapse was suspected during follow-up. The results obtained suggest that antibody detection techniques, the antigen detection in urine (KAtex kit), and Leishmania nested PCR (LnPCR) analysis of the blood could be used for diagnosis of the first clinical episode. After treatment, clinical improvement was associated with negativization of Novy-MacNeal-Nicolle culture and microscopy of bone marrow aspirate, KAtex test, and LnPCR blood analysis results. Interestingly, LnPCR analysis of the bone marrow aspirate showed that sterile cure was not achieved in eight patients, two of which suffered a relapse within 10 to 20 weeks. All of the new noninvasive techniques tested showed high diagnostic sensitivity. However, LnPCR analysis of the bone marrow was the most sensitive; this test was able to detect the persistence of parasites and predict potential relapses.

Amphotericin B↗

PubMed2006

Leishmania/HIV co-infections in the second decade.

Leishmania-HIV co-infection has been globally controlled in Southern Europe since 1997 because of highly active anti retroviral therapy (HAART), but it appears to be an increasing problem in other countries such as Ethopia, Sudan, Brazil or India where both infections are becoming more and more prevalent. Most of the scientific background on Leishmania/HIV co-infection has been dropped from the Mediterranean experience and although the situations among countries are not fully comparable, it is of high importance to take advantage of this knowledge. In this review several aspects of the Leishmania/HIV co-infection are emphasized viz., epidemiological features, new ways of transmission, pathogenesis, clinical outcome, diagnosis, treatment and secondary prohylaxis. An extensive review of the literature on Leishmania/HIV co-infection has allowed the inclusion of a comprehensive and updated list of bibliographical references.

AIDS-Related Opportunistic Infections↗

PubMed2005

diastereoselective intramolecular Alder-Ene reaction on chiral perhydro-1,3-benzoxazines. a rapid entry to enantiopure cis-3,4-disubstituted pyrrolidines.

Chiral 3-acryloyl-2-vinyl-substituted 1,3-perhydrobenzoxazines derived from (-)-8-aminomenthol participate in an ene reaction leading to 3,4-disubstituted pyrrolidinone derivates with excellent diastereoselectivity. The cycloadducts were transformed into enantiopure 3,4-disubstituted pyrrolidines after elimination of the chiral adjuvant.

Journal Article↗

PubMed2005

Diastereoselective yang photocyclization reactions in solution. synthesis of enantiopure azetidin-3-ol derivatives.

[reaction: see text] Chiral 2-acyl-3-allyl- or 2-acyl-3-benzyl-substituted perhydro-1,3-benzoxazines readily cyclized under irradiation to azetidin-3-ol derivatives. The diastereoselectivity of the cyclization is dependent on the nature of the substituents at the nitrogen atom. N-allyl-substituted derivatives yielded only two of the four possible diastereomers in moderate to good diastereomeric excess. The cyclization of N-benzyl derivatives was totally diastereoselective leading to a single diastereomer. The elimination of the menthol appendage lead to enantiopure 2,3-disubstituted azetidin-3-ol derivatives.

Journal Article↗

PubMed2004

Canine leishmaniasis.

Canine leishmaniasis is caused by Leishmania infantum (syn. L. chagasi, in America) and is transmitted by the bite of phlebotomine sand flies. Infected dogs constitute the main domestic reservoir of the parasite and play a key role in transmission to humans, in which the parasite produces visceral leishmaniasis. The increasing awareness that control of the human disease depends on effective control of canine leishmaniasis has promoted, in the last few years, research into leishmanial infection in dogs. Newly available specific reagents and molecular tools have been applied to the detailed investigation of canine leishmaniasis and important advances have been made in elucidating the epidemiology and pathology of the disease. These new findings have led to better understanding of the disease, and have also helped in the development of new diagnostic methods and control measures against the infection, such as insecticide-impregnated collars for dogs, new drugs and treatment protocols, and second generation vaccines, with the hope of not only reducing the heavy burden of the disease among dogs but also reducing the incidence of human visceral leishmaniasis.

Animals↗

PubMed2003

Synthesis of enantiopure 3-azabicyclo[3.2.0]heptanes by diastereoselective intramolecular [2+2] photocycloaddition reactions on chiral perhydro-1,3-benzoxazines.

[2+2] photocycloadditions involving chiral 3-acryloyl-2-vinylperhydro-1,3-benzoxazines derived from (-)-8-aminomenthol are highly diastereoselective reactions. The facial selectivity depends on the type of substitution at the vinyl double bond, and always leads to cis-fused bicyclic derivatives. The de is good for compounds with one substituent at the outer carbon of the double bond at C-2, but only one diastereomer is formed in cyclizations of compounds with two substituents at that position. The elimination of the menthol appendage gives enantiopure 3-azabicyclo[3.2.0]heptanes.

Journal Article↗

PubMed2002

A novel synthesis of enantiopure octahydropyrrolo[3,4-b]pyrroles by intramolecular [3 + 2] dipolar cycloaddition on chiral perhydro-1,3-benzoxazines.

[reaction: see text] Condensation of N-substituted glycines with chiral 3-allyl-2-formyl perhydro-1,3-benzoxazines forms an azomethine ylide that cyclizes to give octahydropyrrolo[3,4-b]pyrrole derivatives. The [3 + 2] dipolar cycloadditions are stereoespecific leading to a single diastereoisomer. The chemical yields are dependent on the reaction temperature and the presence or absence of a base.

Cyclization↗

PubMed2002

Stereocontrolled IMDA reaction of styrene derivatives. A way to enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines.

IMDA reactions on chiral perhydro-1,3-benzoxazines, derived from (-)-8-amino menthol, bearing a styrene substituent at C-2 acting as diene and an acryl amide acting as dienophile occur with high stereoselection and excellent chemical yields. After elimination of the chiral appendage, enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines are prepared in this way. The effect of the substituents at both diene and dienophile are studied, showing that a methyl group at C-1 in the diene inhibited the reaction, while the ene adduct, instead of the IMDA product, was obtained when a methyl group was at C-2.

Journal Article↗

PubMed2002

Underdiagnosis of sleep apnea syndrome in U.S. communities.

We hypothesize that clinical recognition rates for obstructive sleep apnea-hypoapnea syndrome (OSAHS) are influenced by comorbidity and demographic factors. Data on medical disorders, symptoms of sleep disorders, and cardiovascular risk factors gathered from 15,699 individuals in the Sleep Heart Health Study were compared. Participants were classified into three groups: those with a self-reported physician diagnosis of OSAHS, those with self-reported physician-diagnosed and -treated OSAHS, and those reporting both frequent snoring and daytime sleepiness (two-symptom group). Among all participants, 4.1% reported two symptoms (range across sites: 1.55 to 7.23%), whereas 1.6% reported a physician diagnosis of OSAHS (range: 0.66 to 2.88%) and 0.6% reported physician diagnosis and treatment (range: 0.11 to 0.88%). Recognized OSAHS groups were similar to the two-symptom group in age, having a sleeping partner, measured blood pressure, total cholesterol, and race. In a logistic model that included age along with characteristics found to vary significantly among the three groups (gender, body mass index [BMI], high-density lipoprotein cholesterol levels, hypertension), only male gender and BMI were increased in those with physician-diagnosed and -treated OSAHS. We conclude that disparities (especially in women and in those with lower BMI) exist between current recognition rates for OSAHS and the estimated prevalence by symptom report across the United States.

Diagnosis, Differential↗

PubMed1996

Synthesis of Enantiopure Primary Amines by Stereoselective Ring Opening of Chiral Octahydro-1,3-benzoxazines by Grignard and Organoaluminum Reagents.

Chiral 1,3-perhydrobenzoxazines 1, 2, and 9-14, prepared by condensation of 8-(benzylamino)menthol with different aldehydes, react with alkylmagnesium bromides and trimethylaluminum leading to the open amino alcohols 3a-d, 4a-d, and 15-20 in excellent chemical yields and good to excellent diastereomeric excess. The sequential elimination of the menthol appendage by heating with P(2)O(5) and the benzyl group by hydrogenolysis lead to primary amines 7a-d, 8a-d, and 27-30 in excellent chemical yields and ee. The addition of the alkyl group from the Grignard derivatives and the methyl group from the trimethylaluminum occurs from opposite sides of the heterocycle, yielding the final primary amines with the same stereochemistry.

Journal Article↗