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Biomedical subjects

F Alvarez

Publications and source records attributed to F Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed1999

Timing of onset of contraceptive effectiveness in Norplant implant users. II. Effect on the ovarian function in the first cycle of use.

The objective of this study was to time the onset of contraceptive effectiveness in Norplant implant users, when the capsules were inserted beyond the first 7 days of the cycle, based on the immediate effect on the ovarian activity. A total of 42 healthy women requesting Norplant implant contraception were enrolled at clinics in Santo Domingo, Dominican Republic, and in Baltimore, Maryland. Implants were inserted on days 8-13 of the menstrual cycle. Blood samples for estradiol (E2), progesterone (P), luteinizing hormone (LH) (in a subset of 12 women), and levonogestrel (LNG) assay, were taken at 0 h and at 6, 12, 24, 72, and 168 h postinsertion. Ovulation, as defined by P > 2.5 ng/mL, occurred in 40% of subjects. A short lasting, frequently blunted, LH peak occurred within 12 h postinsertion, in all these subjects. The remaining subjects had anovulatory cycles with two distinct E2 profiles: continuously increasing E2 levels to a high mean of 414.3 pg/mL (28%), or no sustained increase in E2 (32%). Most cycles (86%) in which Norplant was inserted with high E2 levels (> 175 pg/mL) were ovulatory, whereas none were ovulatory with low E2 (< 100 pg/mL) at insertion. Based on the endocrine effects of Norplant implant insertion in the midadvanced follicular phase, in which ovulation will either occur within 48 h of insertion or will be impaired, additional contraceptive protection is necessary only for 3 days.

Adolescent↗
PubMed1999

Efficacy, bleeding patterns, and side effects of a 1-year contraceptive vaginal ring.

A combined contraceptive vaginal ring designed to last 12 months was tested at three clinic sites. This ring released approximately 1 mg of norethindrone acetate (NET-Ac) and 20 micrograms of ethinyl estradiol (EE) daily. A total of 60 women were enrolled to use the ring in a schedule of 3 weeks in/1 week out. Serum norethindrone (NET) and ethinyl estradiol (EE) levels were assayed twice weekly in cycles 6, 9, and 13. Mean NET concentrations between cycles 6 and 9 were relatively stable between 13 and 19 nmol/L but showed a 10%-21% decrease in all centers between cycles 9 and 13. Mean EE concentrations ranged from 75 to 103 pmol/L, but did not have the same decrease as NET between cycles 9 and 13. Cycles with progesterone peaks (> 9.6 nmol/L) compatible with some luteal activity occurred in 4% of cycles sampled in Sydney, 3% in Santo Domingo, and 26% in Los Angeles. Half of these cycles exhibited at least one progesterone value > 32 nmol/L with three of 18 occurring in noncompliant cycles. Heavier body weight was associated with increased probability of luteal activity. Based on serum estradiol peaks > 400 pmol/L, eight of 81 cycles appeared to have marked follicular activity with no luteal activity. No pregnancies occurred. Nausea was reported by about half the subjects in approximately 10% of the visits (mainly in the first 1-2 days in the first cycle immediately after ring insertion). Vomiting was reported by 20% of subjects early in the first cycle only. Headache was reported on occasion by nearly 50% of the women, but the relationship to ring use was uncertain. Vaginal discharge was reported by 17 women (82% of these were from one clinic). Of 60 women, 14 discontinued before completing the study, but only two discontinuations were for medical reasons. Small but statistically significant changes occurred in lipid levels in two of the three centers. All changes remained within normal limits and were similar to those seen with many oral contraceptives. It appears that this ring may perform slightly differently in different populations, but is a highly satisfactory method of contraception for many women. Minor modifications in design could provide higher levels of steroid release and in the later months of the ring life span would assure continuing high levels of contraceptive protection for heavier women.

Adolescent↗
PubMed1999

Formiminotransferase cyclodeaminase is an organ-specific autoantigen recognized by sera of patients with autoimmune hepatitis.

BACKGROUND & AIMS: Anti-liver cytosol type 1 autoantibodies have been reported in association with anti-liver-kidney microsome type 1 autoantibodies in 30% of patients with autoimmune hepatitis type II. In 10% of cases, anti-liver cytosol type 1 antibodies are the only liver-related circulating autoantibodies. The liver cytosol antigen is a liver-specific 62-kilodalton protein present in the cell as an oligomer of approximately 240 kilodaltons. The aim of this study was to identify the antigen recognized by anti-liver cytosol antibody. METHODS: To identify the liver cytosol antigen, an anti-liver cytosol type 1-positive serum was used for the screening of a complementary DNA library from HepG2 cells. Double immunodiffusion method was used to show the identity between the cytosolic and the cloned protein. RESULTS: The sequence of two isolated clones showed 85.2% homology with the formiminotransferase cyclodeaminase (FTCD) enzyme from pig liver. Antibodies purified by affinity with the recombinant protein and sera from mice immunized with FTCD recognized a 62-kilodalton human cytosolic protein when tested by immunoblot. The identity of precipitation lines was found between the cytosolic antigen and FTCD. CONCLUSIONS: This enzyme is a liver-specific antigen recognized by the sera of patients with autoimmune hepatitis.

Amino Acid Sequence↗
PubMed1999

Short-term cyclosporine induces a remission of autoimmune hepatitis in children.

BACKGROUND/AIMS: The current immunosuppressive treatment of patients with autoimmune hepatitis consists of prednisone and azathioprine. High doses of prednisone used to obtain the remission of the disease are associated with serious adverse effects. To avoid harmful consequences of prednisone therapy, we proposed to treat patients with oral cyclosporine to obtain the remission of the inflammatory process. METHODS: This is a pilot, multinational, multicenter, clinical trial involving children with autoimmune hepatitis. Thirty-two children were recruited, who according to international criteria were considered as having definite autoimmune hepatitis. Cyclosporine alone was administered for 6 months, followed by combined low doses of prednisone and azathioprine for 1 month, after which cyclosporine was discontinued. Biochemical remission of the disease was established by the follow-up of serum transaminase activity levels. Growth parameters and adverse effects of the treatment were recorded. RESULTS: Two patients were withdrawn from the study: one for non-compliance and the other for liver failure which did not improve with cyclosporine. Of the 30 remaining patients, 25 normalized alanine aminotransferase activity levels by 6 months and all the patients by 1 year of treatment. Z-scores for height showed a trend towards improvement during treatment. Adverse effects of cyclosporine were mild and disappeared during weaning off the medication. CONCLUSIONS: Cyclosporine induced the biochemical remission of the hepatic inflammatory/necrotic process in children with autoimmune hepatitis, with few and well-tolerated adverse effects.

Adolescent↗
PubMed1999

Correlation of endocrine profiles with bleeding patterns during use of Nestorone contraceptive implants.

The relationship between ovarian hormones and bleeding patterns during continuous progestin contraception was studied in 29 women who used Nestorone (NES) releasing implants. Oestradiol and progesterone were measured in blood samples taken twice a week for 6 consecutive weeks, during months 6, 12, 18 and 24 of implant use. Retrospectively, the association between hormonal concentrations and bleeding patterns was evaluated. Twenty-four short (</= 24 days), 36 normal (25-35 days), 27 long (36-90 days) and nine episodes of amenorrhoea, as well as 28 periods of prolonged bleeding, were identified. Short cycles, periods of prolonged bleeding and amenorrhoea were characterized by low oestradiol concentrations. Bleeding after a normal or long cycle regularly occurred after a rise and fall of oestradiol or oestradiol and progesterone. The duration of bleeding was directly and significantly associated with the highest concentration of oestradiol in the previous 15 days in anovulatory cycles. Luteal activity was associated with shorter duration of bleeding. Periods of prolonged bleeding were usually initiated with a drop in oestradiol and over half ended with an increase in oestradiol. It was concluded that changes in endogenous hormone have a significant influence over the bleeding pattern during use of NES implants.

Adolescent↗
PubMed1999

Variations in vaginal epithelial surface appearance determined by colposcopic inspection in healthy, sexually active women.

A total of 107 sexually active women, aged 18-35 years, was recruited through family planning clinics in four centres in different countries. Each woman underwent two or three gentle but thorough and systematic vaginal inspections using a consistent technique with colposcopic magnification over a 4-6 month period to look for changes in vaginal and cervical appearance which might be related to sexual intercourse, tampon use, contraceptive method used, cigarette smoking or other environmental factors. Obvious changes in appearance were photographed at x10 magnification. These 'appearances' or 'conditions' were classified according to a modification of the recommendations of a workshop sponsored by the World Health Organization, the Population Council and the Conrad Program. Most of these alterations in the appearance of the vaginal epithelium were judged to be of such minor clinical importance that they have been termed 'conditions' or 'changes in appearance' rather than 'lesions'. In all, 56 'conditions' or 'appearances' were noted in 314 inspections, the commonest being petechiae (53.6%). Potentially significant conditions justifying the term 'lesions' (three microulcerations, two ecchymoses, five abrasions and one mucosal tear; 3.5% of inspections) usually healed spontaneously and disappeared rapidly. The incidence of these conditions was highest when the inspections followed intercourse in the previous 24 h (25.2 versus 14.2%; P < 0.0008), or tampon use (32.4 versus 15.9%; P < 0. 0001). These processes may be regarded as a reflection of regular minor trauma to the vaginal epithelium.

Adolescent↗
PubMed1999

Accuracy of the [13C]-urea breath test in diagnosing Helicobacter pylori gastritis in pediatric patients.

BACKGROUND: The causal association between Helicobacter pylori (H. pylori) colonization of the gastric mucosa and gastritis is now well established. Histologic examination of endoscopic biopsy specimens has long been regarded as the gold standard for diagnosis. However, the changes can be focal in nature and presence of the organism may be missed in nonsampled areas. The urea breath test, which uses a stable isotope, offers distinct advantages, in that it is noninvasive and measures the activity of the micro-organism. It thus represents a potentially invaluable tool in the initial diagnosis of the infection and in verifying its eradication. METHODS: The study design was that of a prospective, blinded comparison of the [13C]-urea breath test with histologic assessment of antral biopsy specimens using the Warthin-Starry stain, to diagnose H. pylori infection in a group of 79 consecutive pediatric patients. RESULTS: Patients classified as negative by histology (n=67) had breath 13C enrichment of 0.97+/-0.07 delta per thousand (mean+/-SEM), with a range of -0.20 and 2.83 delta per thousand. In contrast, those with a positive histologic results (n=12) had an enrichment of 25.41+/-5.01 delta per thousand (range, 3.43-58.80; p < 0.001). At the chosen cutoff point of 3 delta per thousand, the sensitivity and specificity as well as the positive and negative predictive values of the breath test were uniformly 100%. CONCLUSION: The [13C]-urea breath test is a highly reliable, noninvasive method for the diagnosis of H. pylori gastritis in children and adolescents.

Adolescent↗
PubMed1999

Sera of children with hepatitis C infection and anti-liver-kidney microsome-1 antibodies recognize different CYP2D6 epitopes than adults with LKM+/HCV+ sera.

BACKGROUND: Liver-kidney microsome type 1 (LKM1) antibodies are specific markers of autoimmune hepatitis (AIH) type 2. Antibodies to LKM1 have been found in 2% to 3% of adults infected with hepatitis C virus (HCV) without AIH. Thirty percent of these antibodies are directed against linear sequences of CYP2D6 protein. LKM1 antibodies in HCV+/LKM1+ sera and in sera of AIH patients do not recognize the same CYP2D6 epitopes. The current study was conducted to determine whether LKM1 antibodies in HCV+/LKM1+ children's sera are the result of the same immune response as the antibodies described in AIH type 2 and in HCV+/LKM1+ adult patients. METHODS: Sera from 10 HCV+/LKM1+ children were tested against human liver microsomal and cytosolic proteins by Western blot analysis and against synthetic peptides of the CYP2D6 sequence between amino acids 200 and 429 by dot blot. The same sera were tested against radiolabeled CYP2D6 by immunoprecipitation. RESULTS: Four of 10 sera tested by Western blot analysis showed immunoglobulin (Ig) G-type antibodies against CYP2D6, and 2 had antibodies against proteins of 58, 66, and 84 kDa. One of the sera also contained IgM-type anti-66-kDa and 84-kDa proteins. The radioligand test detected anti-CYP2D6 antibodies in 9 of 10 patients. Five of the anti-CYP2D6-positive sera recognized a peptide between amino acids 200 and 429 including amino acids 254-271. CONCLUSIONS: Most HCV+/LKM1+ sera from children recognize conformational epitopes of the CYP2D6 antigen, and half recognize linear epitopes. Some HCV+/LKM1+ sera demonstrated antibodies against the AIH type 2 main antigenic site of the CYP2D6. Screening of HCV RNA should be performed before starting treatment of presumed autoimmune hepatitis associated with LKM1.

Adolescent↗
PubMed1999

Severe autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy in an adolescent girl with a novel AIRE mutation: response to immunosuppressive therapy.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder for which the gene (AIRE) has recently been identified on chromosome 21q22.3. We present the mutational analyses of a French-Canadian family with APECED, in which there are two affected siblings, as well as the response to cyclosporine A(CyA) therapy in the index patient, the eldest sibling. Haplotype analysis suggested compound heterozygozity at the AIRE locus. Direct sequencing of exon 8 revealed a previously described mutation, a 13-bp deletion (1085-1097) of maternal origin, found in the index patient, her affected sister, and her unaffected sister. A novel missense mutation characterized by a T-->G transversion at nucleotide position 398, resulting in a leu-->arg amino acid substitution (L93R), was found in exon 2. The mutation was present in the father, the brother, the index patient, and the affected sister. The presence of the mutation in the propositus was verified by cloning of PCR products from genomic DNA. The mutation destroys a PstI restriction enzyme site, as confirmed in the aforementioned patients. Screening of 50 French-Canadian controls with PstI digestion did not show destruction of the restriction-enzyme site. The index patient's phenotype was severe, manifested by classic features of the illness (adrenal insufficiency, hypoparathyroidism, candidiasis, and keratoconjunctivitis with alopecia universalis), as well as by severe exocrine pancreatic insufficiency, diabetes mellitus, hepatic inflammation, growth hormone (GH) deficiency due to lymphocytic hypophysitis, and primary ovarian failure. Oral CyA (5 mg/kg/day) was initiated at 13 yr of age. After 8 months of therapy, stimulated pancreatic lipase increased 24-fold with normalization of stool fat (from 31.5 g/day to 2.5 g/day, normal(N) < 5). There was complete resolution of her photophobia, and considerable hair regrowth was diffusely apparent. Minimal side effects were noted. Our experience supports the use of oral CyA for the treatment of severe APECED-associated exocrine pancreatic failure and keratoconjunctivitis.

Adolescent↗
PubMed1999

Hb D-Los Angeles associated with Hb S or beta-thalassemia in four Mexican Mestizo families.

Twenty-five individuals were studied from four unrelated Mexican Mestizo families with Hb D-Los Angeles. We observed five compound heterozygotes: four for Hb S and Hb D, and one for Hb D and beta-thalassemia (beta(0) 39 nonsense mutation); 16 heterozygotes: four for Hb S, seven for Hb D, and five for beta-thalassemia, while the remaining four were normal. The four Hb S/Hb D patients had severe hemolytic anemia, while in the Hb D/beta-thalassemia patient, the anemia was similar to that of a beta-thalassemia heterozygote; therefore, Hb D is clinically harmful when it is associated with Hb S. The beta(S) chromosomes were associated with the Benin haplotype in two families and Bantu in one family, while the beta(D) and beta(0) 39 mutations were associated with haplotype 1 [+ - - - - + +]. The Bantu and Benin haplotypes have been found with high frequency in Hb S individuals from the East Coast and Northwestern Mexico. The beta(D) chromosomes from Italy were also shown to be associated with haplotype 1, the most frequently observed haplotype in the world; there are no haplotype studies on beta(D) chromosomes from India or China where Hb D-Los Angeles is most common. Thus, the true origin of this mutation observed in these Mestizo families remains to be elucidated.

Adolescent↗
PubMed1999

Discapseudes holthuisi (Crustacea: Tanaidacea) as an intermediate host of Caballerorhynchus lamothei (Acanthocephala: Cavisomidae).

The intermediate host of the acanthocephalan Caballerorhynchus lamothei Salgado-Maldonado, 1977, is reported for the first time. Cystacanths of C. lamothei were found in the hemocoel of the tanaid shrimp Discapseudes holthuisi Bacescu and Gutu, 1975, in Alvarado and Sontecomapan lagoons, Veracruz, Mexico. This is the first report of a palaeacanthocephalan using a tanaid shrimp as an intermediate host. Prevalence by locality, shrimp length, sex and developmental stage, and an analysis of the distribution of number of cystacanths per host are presented. A higher prevalence, and percentage of multiple infections and larger host size were found in Alvarado Lagoon.

Acanthocephala↗
PubMed1998

Seasonal changes in the lymphoid organs of wild brown trout, Salmo trutta L: a morphometrical study.

A morphometrical evaluation was made of the seasonal changes affecting the numbers of lymphocytes in the thymus, spleen and pronephros of wild brown trout, Salmo trutta, while the size of the thymus and the three thymic zones were also determined. Results reveal statistically significant changes throughout the year in the number of lymphocytes in the lymphoid organs studied. The spleen and pronephros have similar annual patterns of lymphocyte distribution with high numbers in two seasons, spring and autumn, and two periods of lymphoid involution in winter and summer. The highest numbers of thymocytes occur in trout caught in May and August, and the lowest in winter. In addition to normal lymphocytes, degenerated lymphoid cells that show pale cytoplasm devoid of cell organelles, also occurred in all the lymphoid organs. A negative correlation exists between the numbers of normal lymphocytes and that of degenerated lymphoid cells. The thymic size, as well as that of the subcapsular, inner and outer thymic zones, undergo very significant changes over the year. We discuss the relevance of cell proliferation, cell migration and in situ cell death for the circannual variations observed in the cell content of trout lymphoid organs, together with the possible causes.

Animals↗
PubMed1998

Sex hormone binding globulin and free levonorgestrel index in the first week after insertion of Norplant implants.

Levonorgestrel has an inhibitory effect on sex hormone binding globulin (SHBG). This decrease in SHBG leads to an increase in the free levonorgestrel index (FLI), which has a stronger biological effect. The interaction between serum levels of levonorgestrel and SHBG in long-term users of Norplant implants has been described. This study was designed to understand the same interaction immediately after the insertion of the implants, in a group of 16 women, sampled at 0 and 6 h and at 1, 3, and 7 days after Norplant implant insertion. Peak serum levonorgestrel levels were achieved at 24 h after insertion, remaining stable on day 3 and decreasing by > 10% by day 7. SHBG did not change during the first 24 h, but decreased by 19% and 60% on days 3 and 7, respectively. FLI more than doubled from day 1 to day 7 after insertion. The large decrease in SHBG and doubling of FLI is not followed by a similar reduction in levonorgestrel, which is hard to explain without an increase in the release rate of the steroid from the capsule.

Contraceptive Agents, Female↗
PubMed1998

Contraception with two levonorgestrel rod implants. A 5-year study in the United States and Dominican Republic.

A 5-year trial of a two-rod contraceptive implant, which releases the progestin levonorgestrel (LNG rod), was conducted at four clinics with 594 women. Mean age and weight at admission were 25.5 years and 62.4 kg, respectively. Consent to continue through 5 years was sought and obtained when the 3-year cumulative pregnancy rate proved to be 0.8 per 100. No pregnancies occurred in the fourth or fifth years. The 5-year cumulative pregnancy rate was, therefore, 0.8 per 100 with an annual average pregnancy rate below 2 per 1000 women. Prolonged bleeding/spotting (8.2% of subjects) and irregular bleeding (5.6%) were the most frequently cited medical reasons for removal. Removals for headache (4.7%) and weight change (4.0%) were the next most frequent medical reasons. Between 1% and 2% of subjects during the 5-year trial sought removals for each of the following conditions: mood changes, lower abdominal pain, depression, or pain at the implant site. The mean annual continuation rate during the study was 77 per 100. Use per woman averaged 2.96 years. Mean removal time was 5.9 +/- 0.6 min. These data indicate that, for a 5-year period, the two LNG rod implants are equivalent to the six Norplant capsule implants with respect to safety and efficacy parameters, but permit easier and more rapid implant removal.

Adolescent↗
PubMed1998

Timing of onset of contraceptive effectiveness in Norplant implant users. Part I. Changes in cervical mucus.

OBJECTIVE: To provide scientific data regarding the changes in cervical mucus within the first hours to days after Norplant implant insertion and to estimate when the cervical mucus is hostile enough to suggest a contraceptive effect. DESIGN: Multicenter, clinical descriptive study. SETTING: Family planning clinics. PATIENT(S): Forty-two women who were between days 8 and 13 of their menstrual cycle and who had requested Norplant implants were admitted to the study. INTERVENTION(S): Cervical mucus and blood samples were obtained. MAIN OUTCOME MEASURE(S): Cervical mucus scores, sperm penetration distances, and serum levels of progesterone, estradiol, and levonorgestrel. RESULT(S): The median cervical mucus score observed at baseline was 6 ("fair"), indicating that the mucus was already somewhat hostile before insertion of the Norplant implants. The median scores declined to 5 at 12 and 24 hours and continued to decrease through day 7 to 2 ("poor"), a score that is judged as hostile to sperm penetration. Overall, 73% of all subjects had a poor cervical mucus score by 3 days after insertion; at 7 days after insertion, 90% exhibited poor mucus and none had a good score. There was a substantial drop in the overall median distance traveled by the vanguard sperm after 12 hours for each cervical mucus score grouping. The distance traveled decreased rapidly between 12 and 24 hours to < 0.5 cm in subjects with fair and poor mucus, and by day 3, 91% of the subjects exhibited poor sperm penetration. CONCLUSION(S): On the basis of our findings, deterioration of the quality of the cervical mucus and sperm penetration is evident by 24 hours after insertion, although not to a level that would suggest adequate protection until 72 hours after insertion. Therefore, we are confident in recommending that backup methods of contraception (e.g, condoms) need not be used for more than 3 days after insertion, even when the implants are inserted close to ovulation. These findings provide policy makers, clinic managers, and clinicians with important information about how they can improve client access to Norplant implants.

Adult↗
PubMed1998

Interferon alfa therapy for chronic hepatitis B in children: a multinational randomized controlled trial.

BACKGROUND & AIMS: Treatment of chronic hepatitis B with interferon alfa is not approved in children. The aim of this study was to evaluate the safety and efficacy of interferon alfa (IFN-alpha) in children with chronic hepatitis B and increased transaminase levels. METHODS: Children were given either IFN-alpha2b (6 megaunits/m2 thrice weekly for 24 weeks) or no treatment. Clearance of markers of viral replication was evaluated 24 weeks after therapy and after 48 weeks of observation in controls. RESULTS: Of 149 children enrolled, 144 were evaluable (70 treated and 74 controls). Serum hepatitis B e antigen and viral DNA became negative in 26% of treated children and 11% of controls (P < 0.05). Serum aminotransferase levels normalized and liver histology improved among responders. Hepatitis B surface antigen became undetectable in 10% of treated patients and 1% of controls. Female gender and interferon treatment were the only significant predictors of response. Ethnic origin, baseline aminotransferase level, initial DNA levels, and histology did not correlate with response. Most adverse reactions were mild or moderate, and dose was reduced in 24% of children. CONCLUSIONS: In children with chronic hepatitis B, INF-alpha promotes loss of viral replication markers and surface antigen and improves aminotransferases and histology.

Adolescent↗