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Biomedical subjects

D Cortes

Publications and source records attributed to D Cortes.

At least 37 records · Page 2Linked to original sources
PubMed1999

Specific interactions of monotetrahydrofuranic annonaceous acetogenins as inhibitors of mitochondrial complex I.

Annonaceous acetogenins (ACG) are a wide group of cytotoxic compounds isolated from plants of the Annonaceae family. Some of them are promising candidates to be a future new generation of antitumor drugs due to the ability to inhibit the NADH:ubiquinone oxidoreductase of the respiratory chain (mitochondrial complex I), main gate of the energy production in the cell. ACG are currently being tested on standard antitumor trials although little is known about the structure activity relationship at the molecular level. On recent studies, the relevance of several parts of the molecule for the inhibitory potency has been evaluated. Due to the great diversity of skeletons included in this family of natural products, previous studies on the presence and distribution of oxygenated groups along the alkyl chain only covered the compounds with different bis-tetrahydrofuranic (bis-THF) relative configurations. Therefore, we have investigated the inhibitory action of all the mono-tetrahydrofuranic (mono-THF) acetogenins available, which differ in the oxygenated arrangements along the molecule. Our results show that the hydroxyl and carbonyl groups, placed in the aliphatic chain that links the initial gamma-lactone moiety with the dihydroxylated tetrahydrofuranic ring system, significantly contribute for modulating the inhibitory potency of the ACG through specific effects.

Animals↗
PubMed1999

[Eosinophilic cystitis in children].

Eosinophilic cystitis is an inflammatory disorder of the urinary bladder, characterised by irritative voiding symptoms, negative urine cultures, and eosinophilic infiltration of the bladder wall. Since 1960 only about 20 cases have been described in the English scientific reports, making it a rather rare entity. In children the disease appears to be shortlived and self-limited, requiring no specific treatment. We present a case with a 7.5-year-old boy, who experienced spontaneous remission of all symptoms, following an acute attack of eosinophilic cystitis.

Child↗
PubMed1999

Kinetic characterization of mitochondrial complex I inhibitors using annonaceous acetogenins.

The NADH:ubiquinone oxidoreductase (complex I) of the mitochondrial respiratory chain is by far the largest and most complicated of the proton-translocating enzymes involved in the oxidative phosphorylation. Many clues regarding the electron pathways from matrix NADH to membrane ubiquinone and the links of this process with the translocation of protons are highly controversial. Different types of inhibitors become valuable tools to dissect the electron and proton pathways of this complex enzyme. Therefore, further knowledge of the mode of action of complex I inhibitors is needed to understand the underlying mechanism of energy conservation. This study presents for the first time a detailed exploration of the inhibitory action of the Annonaceous acetogenins, the most powerful inhibitors of the mammalian enzyme, taking as the head-series rolliniastatin-1, rolliniastatin-2, and corossolin. Despite their close chemical resemblance, each of them inhibits the complex I with different kinetic features reflecting differential binding to the enzyme.

Animals↗
PubMed1999

[Renal and urinary tract abnormalities in small children].

The purpose of this study was to investigate frequency and pattern of urological abnormalities in children younger than two years of age in the county of Frederiksborg, Denmark, with a catchment area of about 350,000 people, and furthermore to investigate in which way the urological abnormalities were diagnosed. From 1994-1996 a total of 35 children younger than two years of age were found to have urological abnormalities. Fourteen patients had a ultrasonographical prenatally diagnosed urological abnormality, which was confirmed postnatally. Twenty-one children were diagnosed with urological abnormalities after presentry with their first urinary tract infection. The obstructive urological diagnoses: congenital hydronephrosis, congenital megaureter and posterior urethral valves made up to 57% (20/35) of the abnormalities. Nine boys were operated upon; three for unilateral hydronephrosis, two for posterior urethral valves, one for unilateral megaureter and three for phimosis. Two girls were treated with oestrogen for labial fusion. Urological abnormalities which were treated were found among the ultrasonographically diagnosed abnormalities, apart from phimosis and labial fusion. The frequency of urological abnormalities was 0.25% in children younger than two years of age in Frederiksborg county. In conclusion, in 1994-1996 the frequency and pattern of urological abnormalities in Frederiksborg county was in accordance with the figures in the literature. Urological abnormalities requiring treatment were diagnosed in 11 children; 55% (6/11) ultrasonographically and 45% (5/11) by examination of the external genitalia of children younger than two years of age at the time of the first diagnosed urinary tract infection.

Abnormalities, Multiple↗
PubMed1999

[T validity of the diagnosis of urinary tract infection in children under two years of age].

In the Department of Paediatrics at Hillerød a valid diagnosis of urinary tract infection in children is defined to be at least 10.000 bacteria/ml. in two midstream specimens of urine or any bacterial growth in urine collected by a suprapubic aspiration or by bladder catheterisation. We decided to study if these criteria were fulfilled in our department, which takes care of urinary tract infections in children in the county of Frederiksborg with a catchment area of about 350.000 people. From 1994-1996 a total of 60 children younger than two years of age were treated for their first suspected urinary tract infection. The diagnosis was valid in 37% of the cases. Eighty-eight percent of the children received parenteral antibiotics for at least three days, and 86% were discharged with prophylactic antibiotics. All underwent urological ultrasonographic examination and 70% underwent an isotope micturition cystourethrography. Among patients with a valid diagnosis 68% were boys and 50% had urological abnormalities, whereas among patients without a valid diagnosis there were 33% boys (p < 0.025) and 24% had urological abnormalities (p = 0.0734). A valid diagnosis of a first urinary tract infection was established in 0.15% of children younger than two years of age in the county of Frederiksborg. This is lower than previously reported. The problem of false positive urinary tract infections thus may be important in general.

Age Factors↗
PubMed1999

Semisynthesis and cytotoxicity of styryl-lactone derivatives.

The cytotoxicity and the cell-cycle action of altholactone (1), goniofufurone (2), and eight altholactone derivatives (5-12), were determined in vitro on L-1210 cells. Semisyntheses and structure-activity relationships of these compounds are described. The results of this study suggest that the cytotoxicity of altholactone (1), 11-nitro-altholactone (8), and 7-chloro-6,7-dihydroaltholactone (10) is due to the accumulation of the cells in the G2 + M phase of the cell cycle.

Animals↗
PubMed1999

Germ cells may survive clipping and division of the spermatic vessels in surgery for intra-abdominal testes.

PURPOSE: Laparoscopy is a well described modality that provides an accurate visual diagnosis upon which further management of intra-abdominal testes may be based. Laparoscopic ligation of spermatic vessels as stage 1 of the procedure is a natural extension of laparoscopy. A staged approach provides adequate viability of the intra-abdominal testis. However, it is uncertain whether the more sensitive germ cells survive this procedure in addition to the Sertoli and interstitial cells of the human testis. Survival of germ cells is a prerequisite of later fertility potential. MATERIALS AND METHODS: We studied 17 nonpalpable testes in 10 patients 1 year and 7 months to 13(1/2) years old. Results of testicular biopsies of 13 intra-abdominal testes taken at stages 1 and 2 of surgery were available for histological comparison. RESULTS: Median number of spermatogonia per tubular cross section of the biopsies taken at stage 2 was slightly lower (0.03) compared to the median number at stage 1 (0.06) of the operation but this difference was not significant (p = 0.2031). CONCLUSIONS: Our study shows that the spermatogonia may survive clipping and division of the spermatic vessels, although the number of spermatogonia per tubular transverse section decreases slightly.

Adolescent↗
PubMed1999

Anti-MIC2 as a tool in examination of testicular biopsies.

MIC2 is a pseudoautosomal gene localized on X and Y chromosomes. The MIC2 gene product is a glycoprotein expressed on the cell membranes of a number of somatic cells, including Sertoli cells of the testis, but not on the cell membranes of germ cells. In cases of cryptorchidism, a testicular biopsy is recommended in order to evaluate future fertility potential. The spermatogonia are identified on histological sections and the number per tubular transverse section is compared with normal values for age. The patient is at 33-100% risk of subsequent infertility when the number of spermatogonia per tubular transverse section is lower than 1% of the lowest normal age-matched value. Besides Sertoli cells the seminiferous tubules in undescended testes contain only a few germ cells, and it may be difficult to pinpoint the germ cells in small biopsies. Especially in nonpalpable testes their number may be heavily reduced. A reliable identification of germ cells may also be difficult in cultures of testicular biopsies from undescended testes. Against this background, we tried the use of an immunohistochemical method with DAKO antibody to the MIC2 gene product (MIC2, 12 E7, code no. M3601) in order to obtain a "negative reaction" of germ cells, contrasting with the stained Sertoli cells. The material comprised: 44 specimens of testicular parenchyma taken at time of surgery for cryptorchidism from 24 cryptorchid boys with nonpalpable testes and 14 testicular biopsies from 13 cryptorchid patients with palpable testes which had been cultured in vitro for 7, 14 or 21 days. In all cases the immunohistochemical method with DAKO antibody to the MIC2 gene product was helpful for identification of Sertoli cells and germ cells, and we therefore recommend the use of anti-MIC2 in all testicular biopsies where it is difficult to pinpoint the germ cells.

12E7 Antigen↗
PubMed1998

Enantiospecific semisynthesis of (+)-almuheptolide-A, a novel natural heptolide inhibitor of the mammalian mitochondrial respiratory chain.

The development of novel styryl lactone derivatives as bioactive compounds and the semisynthesis of both 4,5-dialkoxylated eight-membered-ring lactones with a heptolide skeleton (almuheptolide-A (1) type) and 7-alkoxylated delta-lactones with a saturated furanopyrone skeleton (etharvensin (8) type) have been successfully achieved from the chiral unsaturated alpha-pyrone altholactone (7). This new method is a direct and one-step enantiospecific alkoxylation of altholactone (7) in concentrated acid medium, followed by formation of the eight-membered-ring zeta-lactone. The reaction mechanism operating in the synthesis of the heptolide skeleton is postulated to be a direct Michael-type addition. Concerted opening of both the alpha-pyrone and tetrahydrofuran rings and subsequent intramolecular rearrangement with the ring closure lead to almuheptolide-A (1). This compound (1) and its diacetated derivative (1a) showed potent and selective inhibitory activity toward mammalian mitochondrial respiratory chain complex I. This mechanism of action, reported here for the first time, provides a possible explanation for the cytotoxic and antitumor activities previously described for related natural compounds.

Animals↗
PubMed1998

Synthesis and dopamine receptor selectivity of the benzyltetrahydroisoquinoline, (R)-(+)-nor-roefractine.

(R)-(+)-nor-Roefractine (1) was synthesized by the Bischler-Napieralski route, using asymmetric reduction of the 1, 2-didehydro precursor imine with sodium (S)-N-CBZ-prolinyloxyborohydride. Compound 1 was able to displace [3H]-raclopride (a D2 dopamine receptor-selective ligand) from its specific binding sites in rat striatum with selectivity vs [3H]-SCH23390 (D1 dopamine receptor-selective ligand).

Benzazepines↗
PubMed1998

Is infertility after surgery for cryptorchidism congenital or acquired?

We evaluated whether deletions of the DAZ (deleted in azoospermia) gene, abnormal karyotypes or hypogonadotropic hypogonadism (HH) were demonstrable in infertile men who had undergone surgery in childhood for cryptorchidism with a simultaneous testicular biopsy that demonstrated no or almost no germ cells. In six men with infertility after surgery for cryptorchidism, the adult karyotype and analyses for the DAZ gene, serum follicle-stimulating hormone, luteinizing hormone, and testosterone were performed from a peripheral blood sample. Testicular volume was also measured. All patients exhibited a 46,XY karyotype. There were no deletions of the DAZ-gene, no HH and no testicular atrophy. The infertility was thus not proved to be congenital, and consequently, surgical treatment is indicated before the germ cells disappear from undescended testes. This appears to be before 15 months of age.

Adult↗
PubMed1998

Styryl-pyrones from Goniothalamus arvensis.

Two novel styrl-pyrones, (+)-garvensintriol and (+)-etharvendiol, together with a known cytotoxic furano-furone, (+)-goniofufurone, have been isolated from the stem bark of Goniothalamus arvensis. A different relative configuration, cis-erythro-erythro for garvensintriol and cis-threo-erythro for etharvendiol, is established, and their absolute stereochemistry is discussed.

Magnetic Resonance Spectroscopy↗
PubMed1998

10-Oximeguanacone, the first nitrogenated acetogenin derivative found to be a potent inhibitor of mitochondrial complex I.

A new 10-keto bis-tetrahydrofuran acetogenin, guanacone (1), has been isolated from a cytotoxic extract of Annona aff. spraguei seeds. The 10-oximeguanacone derivative 1f is the first bioactive nitrogenated acetogenin found to be a very potent inhibitor of complex I. In addition, a SAR study of guanacone analogues is reported based on the titration of the NADH oxidase and NADH:ubiquinone oxidoreductase activities.

Animals↗
PubMed1998

Cryptorchidism--aspects of pathogenesis, histology and treatment.

Cryptorchidism is the absence of at least one testis in the scrotum. The incidence of cryptorchidism is high and almost 3% of boys in the western countries are operated on for this condition. Abnormalities in the hypothalamo-pituitary-testicular axis may result in cryptorchidism, and cryptorchidism is nearly almost present in individuals with a testis and abnormal sexual differentiation. We characterized an association of cryptorchidism and T10-S5 vertebral, renal and ureteral malformations and dysplasias. Cryptorchidism was ipsilateral to renal and ureteral malformations and dysplasias in more than 90% of cases. The association was proved with increasing frequency in: 4-10% of cryptorchid boys who had undergone laparoscopy for impalpable testes or were expected to be without additional abnormalities; 18% of cryptorchid boys in a material from a department of pediatric surgery; 34% of cryptorchid individuals who had died between week 28 and 40 of gestation; 65% of cryptorchid boys operated on for imperforate anus; all individuals with tritonmelia who are always cryptorchid. As the association was demonstrated with increasing frequency the higher the degree of abnormal differentiation of the caudal developmental field, cryptorchidism may be interpreted as a feature of such an abnormal differentiation. The general significance of our hypothesis is supported by the fact that both position and histology of the undescended testes were independent of a possible presence of the malformations and dysplasias encompassed by the association. Intra-abdominal testes were associated with persisting diaphragmatic ligaments which again were associated with an abnormal differentiation of the midline. Consequently we consider cryptorchidism a feature of abnormalities in the hypothalamo-pituitary-testicular axis and of an abnormal differentiation of the male sexual organs, the midline, and/or the caudal developmental field. The recommended age at surgery for cryptorchidism has gradually been lowered. The recommendations are mainly based on analyses of number of spermatogonia per tubular transverse section in normal and undescended testes. In 1984 when we started our investigations, the biological value of this variable was unclarified.

Adolescent↗
PubMed1998

Cryptorchidism as a caudal developmental field defect. A new description of cryptorchidism associated with malformations and dysplasias of the kidneys, the ureters and the spine from T10 to S5.

Cryptorchidism is a feature of abnormalities in the hypothalamo-pituitary-testicular axis, and almost all disorders of sexual differentiation in which a testis is present. We found cryptorchidism to be associated with malformations and dysplasias of the kidneys, the ureters and the spine from T10 to S5. The description of this association is new. The association was seen in 18% of cryptorchid boys younger than 3 years of age in a department of paediatric surgery, in 34% of cryptorchid foetuses who died in the third trimester, in 65% of cryptorchid patients with imperforate anus, and in all individuals with tritonmelia, the male variant of sirenomelia. Sirenomelia/tritonmelia is an extreme degree of abnormal differentiation of the caudal developmental field, also called caudal dysplasia, the caudal regression syndrome and the caudal regression malformation sequence. Caudal developmental field defects were also the predominant abnormalities in the other groups of patients. Thus, cryptorchidism may be a feature of abnormal differentiation of the caudal developmental field. Position and histology of the undescended testes of the patients included in the association were similar to in cryptorchidism in general. In the literature the association was reported in 5-10% of boys considered to suffer from cryptorchidism only. Furthermore, our observations are concordant with recent theories about cryptorchidism. Consequently, we propose that cryptorchidism in general may be a caudal developmental field defect. Study of cryptorchid patients exhibiting malformations or dysplasias of the kidneys, the ureters or the spine from T10 to S5 is essential in order to isolate new genetic disorders and to spot environmental factors causing cryptorchidism.

Animals↗