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Biomedical subjects

F Alvarez

Publications and source records attributed to F Alvarez.

At least 127 records · Page 7Linked to original sources
PubMed1996

[Resection arthroplasty in the treatment of hallux valgus].

Sixty-six feet operated on for hallux valgus in 1984 were reviewed. Keller-Brandes' operation was performed in all cases, together with Lelièvre's "fibrous cerclage" and flexor hallucis longus tendon anchoring to the sesamoid pad, as described by A. Viladot. In most cases, satisfactory clinical correction was achieved and the patients could wear standard shoes. More than half of the cases presented partial limitation of movement at the first metatarsophalangeal joint; however, flexion power of the big toe was preserved, and the range of motion was wide enough to allow a painless and limp-free gait. Radiologically, good correction of the angle between the first and second metatarsals and the metatarsophalangeal angle was obtained, but all cases presented proximal displacement of sesamoid bones. A baropodometric study showed that the toe-off phase of the gait does not change after this operation. In our series, central metatarsalgia was present in 17 feet; however, it did not compromise the functional result and was easily relieved with orthopaedic devices. Four feet showed radiographic images, suggesting necrosis of the first metatarsal head; all four were asymptomatic. The only case that required reoperation was the one that developed hallux varus deformity. The Keller-Brandes-Lelièvre-Viladot procedure is still a simple and effective method for the surgical treatment of hallux valgus in elderly people with osteoarthritis at the first metatarsophalangeal joint.

Adult↗
PubMed1996

Multicenter clinical trial on the efficacy and acceptability of a single contraceptive implant of nomegestrol acetate, Uniplant.

Uniplant, a single Silastic implant containing nomegestrol acetate, provides contraceptive efficacy for one year. Uniplant use for one year was studied in 1,803 healthy women of reproductive age, enrolled from 10 centers in 9 countries, after informed consent. Implants were placed subdermally either in the upper arm or in the gluteal region. Two-hundred-seventy-six subjects discontinued prior to completing one year of study. Cumulative discontinuation rate at 12 months was 15.72%. Medical reasons for discontinuation were principally menstrual-related. Fifteen pregnancies occurred during the one year study period, resulting in a 12-month net cumulative pregnancy rate of 0.94%. Approximately 56% of subjects using Uniplant had bleeding patterns similar to normal menstruation. Results from this study confirm that Uniplant is an efficient, well tolerated, 12-month contraceptive implant, with the advantage of easier insertion and removal of the single implant compared to other multiple implant methods.

Adult↗
PubMed1996

Ultrasonographic and endocrine evaluation of ovarian function among Norplant implants users with regular menses.

With the objective of evaluating the ovulatory function among long-term Norplant implants users with regular menstrual cycles, we undertook this prospective study including 11 Norplant implants users and 11 control women who were not using hormonal methods of fertility control. Exposed and unexposed women had had at least three regular menstrual cycles preceding enrollment. All women were followed during one menstrual cycle by serial vaginal ultrasound and estradiol (E2), progesterone (P), LH, and FSH measurements. Three Norplant implants users ovulated, three had luteinization of an unruptured follicle (LUF), three had persistent follicle growth up to a mean of 33 mm without rupture, and two had no follicular development beyond 16 mm. Ten of the controls had normal ovulation and one had LUF. Mean peak LH and FSH among Norplant implants users who ovulated were three- to four-fold lower than among controls. Although users of Norplant implants with regular cycles frequently have luteal activity, the results of this study suggest that elevation of P during the second half of the cycle does not necessarily indicate ovulation has occurred and may frequently be associated with the presence of luteinized unruptured follicle. When ovulation occurs, there are usually abnormal hormone levels (low LH/FSH peak, low progesterone) which may also contribute to the contraceptive effect of Norplant implants.

Contraceptive Agents, Female↗
PubMed1996

Results of a user satisfaction study carried out in women using Uniplant contraceptive implant.

A study of the acceptability of Uniplant, a 12-month single implant of nomegestrol acetate, included 819 women from Africa, Latin America, and China, participating in a clinical trial of Uniplant. A standard, pre-coded questionnaire was specially designed for this purpose and applied at the moment of removal of implant, either at the end of 12 months of use or at the time of discontinuation for whatever reason. The level of satisfaction proved high when users' comparison with their previous contraceptive method, users' recommendation of Uniplant to others, users' intention to use the method in the future, and service satisfaction were taken into consideration. Uniplant was considered easy to use, safe (low risk of pregnancy), and also to cause fewer side effects than other methods. When asked about the least liked feature of Uniplant, almost half the respondents said that there was nothing that they disliked and about one-third mentioned the changes in their menstrual pattern. However, according to the clinical trial, over half of the Uniplant users have bleeding patterns similar to untreated cycles. The majority of respondents did not feel any discomfort during the procedure of insertion and removal of the implant. About 70% of patients in the study stated that they required contraception for more than one year and most of these women said that they did not mind having to change the implant every year.

Adult↗
PubMed1996

Effect of preovulatory insertion of Norplant implants over luteinizing hormone secretion and follicular development.

OBJECTIVE: To determine whether the process of ovulation could be interrupted by the insertion of Norplant implants (Leiras Pharmaceuticals, Turku, Finland) in the advanced preovulatory phase. DESIGN: Prospective study. SETTING: The Department of Biomedical Research at the Family Planning Clinic of PROFAMILIA, Santo Domingo, Dominican Republic. PATIENTS: Healthy women of reproductive age, requesting Norplant implants contraception. Thirteen of 15 women volunteers who were admitted completed the study. INTERVENTIONS: Norplant implants were inserted when the dominant follicle reached a mean diameter of 16 mm, based on serial vaginal ultrasounds (US) beginning on day 10 of the cycle. Blood samples for determination of E2, P, LH, and levonorgestrel, were taken and vaginal US performed at 0, 4, 24, 48, and 72 hours after insertion. If follicle rupture had not occurred at 72 hours after insertion, blood sampling and US were done three times per week during 2 additional weeks. RESULTS: Follicle rupture occurred in 11 of 13 subjects within 72 hours after insertion, with the exception of 1 subject in whom rupture occurred between 72 and 192 hours. Two women already had an LH peak at the time of insertion. In 9 of the remaining 11 women, a shortlasting, blunted LH surge was observed at 4 hours postinsertion. In the remaining two women, who had the lowest E2 levels, ovulation was inhibited, and a persistent follicle developed without luteinization. CONCLUSIONS: The insertion of Norplant implants in the advanced follicular phase will not inhibit ovulation if sufficient E2 priming has occurred. On the contrary, the exogenous progestin may rapidly foster ovulation shortly after.

Drug Implants↗
PubMed1996

Study of the B cell response to cytochrome P450IID6 in sera from chronic hepatitis C patients.

Some patients with chronic hepatitis C develop liver/kidney microsome type 1 antibodies. Some of these autoantibodies are directed against the cytochrome P450IID6. The aim of this study was to characterize the immunogenic sites on the P450IID6 molecule recognized by autoantibodies from individuals infected with the hepatitis C virus. Serum from 24 patients with markers of hepatitis C infection and liver/kidney microsome type 1 antibodies were tested by immunoblotting with human liver microsomal proteins. Eight of them with anti-P450IID6 antibodies were tested with synthetic peptides representing P450IID6 putative immunogenic sites and for their capacity to inhibit in vitro P450IID6 enzymatic activity. Anti-P450IID6 antibodies in the sera of chronic hepatitis C patients were of IgG subclass 1 and in one patient also of IgM type. These sera recognized different P450IID6 peptide sequences consisting of amino acids (aa) 200-214 and aa 271-339. The synthetic peptide between aa 321 and 339 appears to represent the main antigenic site. Five out of eight anti-P450IID6 positive sera were also able to inhibit P450IID6 enzymatic activity in vitro at a dilution of 1:100. The anti-P450IID6 autoimmune response in chronic hepatitis C patients is polyclonal, probably inducible, and maintained by the liberation of P450IID6 by hepatocyte lysis. The characterization of the P450IID6 immunogenic site recognized by patients with hepatitis C infection may enable a specific test to be designed to identify those patients with autoimmune hepatitis type 2.

Autoantibodies↗
PubMed1996

Cryopreservation of hematopoietic progenitor cells with 5-percent dimethyl sulfoxide at -80 degrees C without rate-controlled freezing.

BACKGROUND: Cryopreservation of hematopoietic cells with the rate-controlled method is used in the majority of centers. In recent years, there has been a trend toward the simplification of the process. STUDY DESIGN AND METHODS: A simplified method for cryopreservation was developed with 5-percent dimethyl sulfoxide (DMSO) as the sole cryoprotectant without rate-controlled freezing. Experiments were done with progressive concentrations of DMSO, ranging from 0 to 10 percent. With DMSO concentrations from 5- to 10-percent, the best recovery and viability for hematopoietic progenitor cells were observed. Hematopoietic progenitor cells with plasma and 5-percent DMSO were frozen and stored in a -80 degrees C mechanical freezer. Ten patients with solid and hematologic malignancies underwent transplantation with autologous hematopoietic progenitor cells. RESULTS: The median number of transfused mononuclear cells and CD34+ cells was 3.70 (3.1-8.2) x 10(8) per kg and 1.70 (0.8-6.5) x 10(6) per kg, respectively. The median number of transfused colony-forming units-granulocyte-macrophage was 12.45 (3.4-55.3) x 10(4) per kg. All patients showed rapid and sustained engraftment. The mean times to reach a neutrophil count of 0.5 x 10(9) per L and a platelet count of 50 x 10(9) per L were 11.50 +/- 1.70 and 13.90 +/- 3.98 days, respectively. All patients are alive and without transfusion requirements in complete remission 2 to 8 months after transplantation. CONCLUSION: This simplified cryopreservation technique will be useful for institutions without rate-controlled freezing facilities. Moreover, this method diminishes the amount of DMSO infused to patients, as well as its toxicity.

Adolescent↗
PubMed1996

Functional life-span of the dominant follicle in pharmacologically induced anovulatory cycles.

With the purpose of measuring the duration of the functional life-span (FLS) of the anovulatory follicle in women under continuous low-dose progestogen treatment, the oestradiol curve of Norplant implant users was retrospectively analysed. From all the data collected during the previous 5 years at the Department of Biomedical Research at the Family Planning Clinic of Profamilia, Santo Domingo, Dominican Republic, data from all 29 Norplant implant users showing follicular activity without luteal activity were selected for this retrospective analysis. Serial blood sampling twice or three times a week for 5 or 6 consecutive weeks had been taken in all subjects. The duration of the FLS of the dominant follicle in anovulatory cycles was defined at the period from the first day of ascending oestradiol curve until the day preceding onset of menses. The mean FLS of the dominant follicle in anovulatory cycles under continuous low-dose progestogen administration was 21.1 +/- 4.2 days, independently of the length of the menstrual cycle. The duration of the FLS of the anovulatory dominant follicle appears not to be different from the duration of a normal follicle/corpus luteum unit.

Anovulation↗
PubMed1996

Inducible transport of citrate in Lactobacillus rhamnosus ATCC 7469.

Lactobacillus rhamnosus ATCC 7469 exhibited diauxie when grown in a medium containing both glucose and citrate as energy source. Glucose was used as the primary energy source during the glucose-citrate diauxie. Uptake of citrate was carried out by an inducible citrate transport system. The induction of citrate uptake system was repressed in the presence of glucose. This repression was reversible and mediated by cAMP.

Biological Transport↗
PubMed1996

Alagille's syndrome associated with cystic renal disease.

Although renal abnormalities have been described in children with Alagille's syndrome, cystic kidney disease has not often been documented, and then usually only at necropsy. Three children with Alagille's syndrome are described, in two of whom a unilateral multicystic dysplastic kidney was detected by prenatal ultrasound; in the other, a solitary cortical cyst was found later in childhood. All have normal renal function, growth, and liver synthetic function but continue to have clinical and biochemical signs of cholestasis. These cases show that unilateral cystic kidney disease with or without renal dysplasia may be associated with Alagille's syndrome, that the clinical course is not necessarily unfavourable, and that Alagille's syndrome should be included in the differential diagnosis of cystic kidney disorders associated with cholestatic liver disease. Patients with Alagille's syndrome should be evaluated by renal ultrasound.

Adolescent↗
PubMed1996

In vitro and in situ characterization of fish thymic nurse cells.

We present an enzyme- and immuno-cytochemical, and ultrastructural characterization of trout thymic nurse cells (TNCs). Our data suggest that isolated trout thymic multicellular complexes are epithelial cells with acidic compartments that may be involved in the processing of antigens and in the generation of the MHC-II proteins that these cell express, and also that isolated TNCs are the in vitro equivalent of the pale and intermediate electronlucent epithelial cells located in the inner zone of the trout thymus, constituting indirect evidence of the phylogenetical relationships of the inner zone of the teleost thymus with the thymic cortex of higher vertebrates.

Animals↗
PubMed1996

Therapy for chronic viral hepatitis.

Treatment of chronic hepatitis B and C aims to achieve viral eradication. Decreasing the number of carriers subsequently reduces the transmission of the viruses. For an individual patient, therapy is aimed at preventing cirrhosis, liver failure and hepatocarcinoma. Among potential therapies, interferon alfa offers the best results. In one study involving the treatment of children from a region of intermediate endemicity, interferon alfa accelerated the clearance of hepatitis B virus (HBV) replication. In long-term follow-up, the study did not show a significant difference between patients who were treated and those who were not in the rate of disappearance of serum HBV-DNA, normalization of alanine aminotransferase (ALT) levels or seroconversion to antibodies to hepatitis B e antigen. The most important factors in predicting a rapid decrease in HBV replication were AI T levels more than twice normal, low levels of serum HBV-DNA (less than 100 pg/mL) and inflammatory activity on liver biopsy (chronic active hepatitis). A select group of children with HBV infection has thus been shown to benefit from interferon alfa therapy. Treatment should be administered in a dosage of 6 MU/m2 three times each week for 6 months. Chronic active hepatitis, develops in approximately 30% of children with a chronic hepatitis C virus (HCV) infection. Cirrhosis due to HCV appears to be a very rare complication among children. Results of interferon alfa treatment for children with HCV are scarce. A pilot study of 12 children treated with interferon alfa in a dosage of 3 MU/m2 three times each week for 6 months showed that ALT levels normalized in approximately 90% of the patients after 15 months of follow-up. All of the patients had a decrease in the histological activity of the disease. Factors predictive of a favourable response in adults were: low levels of gamma-glutamyl transferase, young age, female sex, short duration of disease, absence of cirrhosis and low histological activity of the disease. Controlled randomized studies are needed to determine the indications for interferon alfa therapy in children infected with HCV. Available data suggest that children may have a better response than adults.

Adult↗
PubMed1995

Physical association and functional relationship between protein kinase C zeta and the actin cytoskeleton.

Protein kinase C (PKC) was initially identified as a serine/threonine protein kinase dependent on calcium and phospholipids and shown to be involved in intracellular signaling pathways. PKC isoforms have been classified into four groups: Ca(2+)-dependent conventional PKC alpha, beta I, beta II, gamma; Ca(2+)-independent, novel PKC delta, epsilon, eta, phi; atypical PKC zeta, lambda, iota which are not activated by Ca2+ or diacylglycerol, and the recently discovered PKCmu. We reported that activation of the zeta PKC isoform is an important step in interleukin-2 (IL-2)-mediated proliferation (Gómez, J., Pitton, C., García, A., Martínez, A., Silva, A. and Rebollo, A., Exp. Cell Res. 1995. 218: 105.). zeta PKC is also required for mitogenic activation of fibroblasts and for the maturation pathway activated by insulin and Ras. Contradictory results have been reported regarding the subcellular redistribution of zeta PKC upon activation. We report here, using confocal microscopy, that IL-2 induces expression, translocation and association of zeta PKC to a structure coincident with the actin cytoskeleton. Furthermore, we show that zeta PKC has a role in maintaining the integrity of the actin cytoskeletal structure in IL-2-stimulated cells. On the contrary, zeta PKC is not involved in the actin cytoskeleton organization when cells are maintained in IL-4, confirming our previous results showing that IL-4-induced signal transduction is PKC independent.

Actins↗
PubMed1995

Compositional correlations in the nuclear genes of the flatworm Schistosoma mansoni.

We have investigated the genome organization in the flatworm Schistosoma mansoni. First, we analyzed the compositional distributions of the three codon positions. Second, we investigated the correlations that exist between (1) the GC levels of exons against flanking regions, (2) the GC levels of third codon positions against flanking regions, (3) the dinucleotide frequencies of exons against flanking regions, and (4) the GC levels of 5' against 3' regions. The modality of the distribution of third codon positions, together with the significant correlations found, leads us to propose that the nuclear genome of this species is compositionally compartmentalized.

Animals↗
PubMed1995

Karyotype evolution in holocentric chromosomes of three related species of triatomines (Hemiptera-Reduviidae).

C-banded karyotypes, DNA content and the male meiiotic process of Triatoma platensis and Triatoma delpontei are compared with those of Triatoma infestans, the main vector of Chagas disease in South America. These three species present the same diploid chromosome number 2n = 22 (20 autosomes + XX male/XY female). They also have several cytogenetic traits that differ from all other triatomines: large autosomes, C-heterochromatic blocks and meiotic heteropycnotic chromocenters formed by autosomes and sex chromosomes. In spite of these similarities, each species presents different chromosomal behavior during male meiosis, distinct DNA content and a specific amount and localization of the C-heterochromatin. The differences in DNA content are mainly due to the variation in C-heterochromatin amount, which may be interpreted as loss and/or gain of C-regions. This interpretation is supported by the presence of meiotic and mitotic chromocenters that facilitate the transference of C-positive material. The cytogenetic data presented in this work suggest that T. infestans and T. platensis are more closely related to each other than to T. delpontei. It can also be inferred that the differences in distribution and amount of heterochromatin do not play a direct role in speciation in this group.

Animals↗
PubMed1995

Conformational epitopes on CYP2D6 are recognized by liver/kidney microsomal antibodies.

BACKGROUND/AIMS: Four linear antigenic sites have been shown on the CYP2D6 molecule that are recognized by serum positive for liver/kidney microsomal antibody (LKM) type 1. The aim of this study was to search for antibodies against CYP2D6 conformational antigenic sites in LKM-1-positive sera. METHODS: The capacity of four LKM-1-positive sera, before and after absorption with synthetic peptides representing CYP2D6 linear antigenic sites, and rabbit sera against linear antigenic sites between CYP2D6 amino acids 254-271 and 373-389 to inhibit the O-demethylation of dextromethorphan by CYP2D6 was tested in vitro. RESULTS: Inhibition of O-demethylation of dextromethorphan was not modified by absorption of antibodies against linear CYP2D6 antigenic sites. In addition, rabbit sera against two of these sites did not inhibit the reaction. These results strongly suggest that antibodies against CYP2D6 conformational antigenic sites were present in LKM-1-positive sera. CONCLUSIONS: The autoimmune response against CYP2D6 is directed against linear and conformational antigenic sites. These results strengthen the argument that the LKM-1 response is polyclonal and antigen driven.

Animals↗
PubMed1995

Histopathology of the thymus in Saprolegnia-infected wild brown trout, Salmo trutta L.

A comparative analysis was made of the thymic cytoarchitecture of healthy and Saprolegnia-infected wild brown trout. In Saprolegnia-infected fish, even when the thymus was not invaded by fungal hyphae, the thymic architecture was lost without signs of regionalization. Intercellular oedema, some thymocytes, hypertrophic and degenerated epithelial cells and increased phagocytic activity were also observed. In thymi invaded by the fungus, hyphae occurred isolated or in close apposition to epithelial cells, and the thymic disorganization was more noticeable. Most thymocytes were pyknotic and both epithelial cells and macrophages contained engulfed dead cells. However, no inflammatory response to the fungal invasion was observed. These results confirm the immunodepressed condition of Saprolegnia-infected wild brown trout previously observed in peripheral lymphoid organs. We discuss the secretion of fungal products and/or the high levels of corticosteroids observed in these fish as possible origins of the condition.

Animals↗