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Biomedical subjects

H Bermúdez

Publications and source records attributed to H Bermúdez.

15 recordsLinked to original sources

Generic sodium stibogluconate is as safe and effective as branded meglumine antimoniate, for the treatment of tegumentary leishmaniasis in Isiboro Secure Park, Bolivia.

Human cutaneous leishmaniasis (CL) and mucous leishmaniasis (ML) are highly endemic in Isiboro Secure Park, which lies in the Bolivian department of Cochabamba--an area where branded meglumine antimoniate (Glucantime) is expensive and poorly distributed. The safety and efficacy of generic sodium stibogluconate (SSG), from Albert David Ltd, was therefore explored, in CL and ML cases from the park, who were treated with 20 mg/kg.day for 20 and 30 days, respectively. A questionnaire recording adverse effects was completed by a physician in each treatment centre. Efficacy of treatment was assessed at the end of treatment and at follow-ups 1 month and 3, 6 and 12 months later. Overall, 146 patients completed treatment with SSG in 2003-2004. No fatalities or severe adverse effects were reported but mild to moderate adverse effects were noted in 41 (28%) of the patients. The incidence of adverse effects was significantly higher among the cases of ML than among the cases of CL. Of the 86 patients with CL who completed 6 months of follow-up, 81 (94.2%) were considered to have been clinically cured; a comparable cohort of 69 CL cases who had been treated with Glucantime in 2001-2002 showed a similar frequency of clinical cure (90%). Generic SSG was shown to be safe and efficacious for the treatment of tegumentary leishmaniasis in Bolivia. Being several times cheaper than Glucantime, it could contribute to improving the access of CL and ML patients to treatment, not only in Bolivia but also in other countries of Latin America.

Adult↗

Schistosoma: cross-reactivity and antigenic community among different species.

It is not unusual to find common molecules among different species of the genus Schistosoma. When those molecules are antigenic, they may be used in immunodiagnosis and vaccines, but they could also be applied to taxonomic and evolutionary studies. To study cross-reactivity and antigenic community among different species of schistosomes, plasmas from laboratory animals infected with Schistosoma bovis, S. guineensis, S. rodhaini, S. haematobium, and four strains of S. mansoni were evaluated with a crude extract of adult worms of S. mansoni by Western blot. Using the multiple antigen blot assay, plasmas from these infected animals were exposed to a selected group of synthetic peptides from Sm28GST, Sm28TPI, Sm elastase, Sm97, Sm32, Sm31, and Sm Cathepsin L. The results presented herein demonstrate differential cross-reactivity and antigenic community among the Mansoni and Haematobium groups of schistosomes, which is of relevance as an additional new tool for phylogenetic studies of schistosomes as well as for diagnosis and vaccine purposes.

Animals↗

Effect of bilayer thickness on membrane bending rigidity.

The bending rigidity k(c) of bilayer vesicles self-assembled from amphiphilic diblock copolymers has been measured using single- and dual-micropipet techniques. These copolymers are nearly a factor of 5 greater in hydrophobic membrane thickness d than their lipid counterparts and an order of magnitude larger in molecular weight M(n). The macromolecular structure of these amphiphiles lends insight into and extends relationships for traditional surfactant behavior. We find the scaling of k(c) with thickness to be nearly quadratic, in good agreement with existing theories for bilayer membranes. The results here are key to understanding and designing soft interfaces such as biomembrane mimetics.

Letter↗

Immunogenicity of polymerizable synthetic peptides derived from a vaccine candidate against schistosomiasis: the asparaginyl endopeptidase (Sm32).

The asparaginyl endopeptidase (Sm32) is expressed in the gastrodermal cells of the schistosome gut and in the head glands of the cercariae. Possibly, Sm32 hydrolyzes pro-proteins involved in the degradation of host hemoglobin [Parasitol. Today 12 (1996) 125]. Preliminary evidences using an Sj32/Sm32 murine vaccine have shown a profound effect on oviposition and worm burden [Chin. J. Schist. Control. 7 (1995) 72; Bull. Human Med. Univ. 24 (1999) 225; Vaccine 20 (2002) 439]. The importance of Sm32 as a novel vaccine candidate is based on the possibility of preventing the maturation of other cathepsins and/or preventing schistosome skin invasion. We studied the immunogenicity of polymerizable peptides derived from Sm32 to select potential protective epitopes. Sm32 prediction of T and B epitopes and homology studies with human legumain were performed. Among the variety of factors that influence the antibody response, we specifically examined the effect of: (i) genetic background of mouse strain, inbred (C57BL/6) versus outbred (Swiss) mice; and (ii) vaccination with a single peptide versus pool of peptides. Swiss mice raised antibodies to three different regions of the Sm32, as tested by the Multiple Antigen Blot Assay (MABA): 182-215 (peptides IMT-70 and 72), 244-273 (IMT-64) and 336-355 (IMT-66). None of these regions were immunogenic for C57BL/6. On the contrary, other peptides, IMT-4 (21-40), IMT-12 (101-120) and IMT-26 (292-313) were highly immunogenic for this inbred strain. Only Swiss mice immunized with a single peptide (IMT-64 and 72) or with three different pools of IMT-peptides (Pool A-II: 14, 16, 18, 70, 72, 89; pool A-III: 22, 64, 24, 26, 28 and pool A-V: 64, 66, 28, 70, 72) recognized the original protein in a crude extract of the worm antigen by Western blot. Peptides IMT-64, 14 and 26 were responsible for this recognition. In general, the vaccination with pool of peptides was more immunogenic for both mouse strains. Predicted B cell epitopes, with hydrophilicity scores over +10 (IMT-12, 64, 26) were always immunogenic after either single or combined peptide vaccination. Sm32 sequences 41-80 (IMT-6 and 8), 141-160 (IMT-16) and 182-215 (IMT-70 and 72) were nearly identical to the corresponding human legumain regions and should be excluded from the human vaccine. We can conclude that the regions of Sm32 that were recognized by antibodies of mice immunized with polymerizable peptides depended on the mice strain and on the hydrophilicity score of the peptides.

Amino Acid Sequence↗

Plasmodium vivax CS peptides display conformational preferences for folded forms in solution.

Spectroscopic techniques have been used to study the conformations of several synthetic peptides with sequences corresponding to the repeat regions of the circumsporozoite proteins of Plasmodium vivax, variants vk-210 and vk-247. As has previously been shown for P. falciparum, turn-like folded conformations are observed, in rapid dynamic equilibrium with extended-chain forms. These results are consistent with the known similarity of the structural, biosynthetic and immunological properties of the circumsporozoite proteins of different plasmodial species. Additionally, the observation of folded conformers provides a rationale for the effectiveness of these peptides as immunogens and potential vaccines.

Amino Acid Sequence↗

Laparoscopic partial nephrectomy for renal tumor: single center experience comparing clamping and no clamping techniques of the renal vasculature.

PURPOSE: We performed a nonrandomized retrospective comparison of 2 techniques for laparoscopic partial nephrectomy, that is without and with clamping the renal vessels. MATERIALS AND METHODS: Between December 1997 and February 2002, 28 consecutive patients underwent transperitoneal laparoscopic partial nephrectomy for renal tumor. In group 1 (12 patients) partial nephrectomy was performed with ultrasonic shears and bipolar cautery without clamping the renal vessels, while in group 2 (16 patients) the renal pedicle was clamped before tumor excision. In group 2 patients intracorporeal kidney cooling was achieved by a ureteral catheter connected to 4C solution. Intracorporeal freehand suturing techniques were used to close the collecting system when opened and approximate the renal parenchyma. RESULTS: All procedures were successfully completed laparoscopically. Mean renal ischemia time +/- SD was 27.3 +/- 7 minutes (range 15 to 47) in group 2 patients. Mean laparoscopic operating time was 179.1 +/- 86 minutes (range 90 to 390) in group 1 compared with 121.5 +/- 37 minutes (range 60 to 210) in group 2 (p = 0.004). Mean intraoperative blood loss was significantly higher in group 1 than in group 2 (708.3 +/- 569 versus 270.3 +/- 281 ml., p = 0.014). Three patients in group 1 and 2 in group 2 required blood transfusions. Immediately postoperatively mean creatinine was 1.26 +/- 0.36 and 1.45 +/- 0.61 mg./dl. in groups 1 and 2, respectively (p = 0.075). Surgical margins were negative in all specimens. Pathological examination revealed renal cell cancer in 18 cases (stages pT1 in 17 and pT3a in 1), oncocytoma in 4, angiomyolipoma in 5 and renal adenoma in 1. CONCLUSIONS: Laparoscopic partial nephrectomy represents a feasible option for patients with small renal masses. Clamping the renal vessels during tumor resection and suturing the kidney mimics the open technique and seems to be associated with less blood loss and shorter laparoscopic operative time.

Aged↗

Laboratory diagnosis of Schistosomiasis in areas of low transmission: a review of a line of research.

After 57 years of successful control of schistosomiasis in Venezuela, the prevalence and intensity of infection have declined. Approximately 80% of the individuals eliminate less than 100 eggs/g of stools, therefore morbidity is mild and the majority are asymptomatic. The sensitivity of Kato-Katz decreases to approximately 60%. Available serological methods for the detection of circulating antigens only reach a 70% of sensitivity. Tests based on the detection of antibodies by immunoenzymatic assays have been improved. The circumoval precipitine test has shown a high sensitivity (97%), specificity (100%), and correlation with oviposition, being considered the best confirmatory diagnostic test. Additionally to the classical immunoenzymatic assays, the development of the alkaline phosphatase immunoassay, allowed to reach a 100% specificity with an 89% sensitivity. Recently, we have developed a modified ELISA in which the soluble egg antigen is treated with sodium metaperiodate (SMP-ELISA) in order to eliminate the glycosilated epitopes responsible for the false positive reactions. The specificity and sensitivity reaches 97% and 99%, respectively. Synthetic peptides from the excretory-secretory enzymes, cathepsin B (Sm31) legumain (Sm32) and cathepsin D (Sm45), have been synthesized. The combination of two peptides derived from the Sm31 have been evaluated, reaching a sensitivity of 96% when analyzed independently and with a 100% specificity. Antibodies raised in rabbits against peptides derived from the Sm31 and Sm32 are currently evaluated in two different antigen-capture-based assays. The development of a simple, cheap and reliable test that correlates with parasite activity is a major goal.

Animals↗

Immunogenicity of synthetic peptides from the Sm31 antigen (cathepsin B) of the Schistosoma mansoni adult worms.

The chemical synthesis of peptides may simplify the production of molecules for diagnosis of Schistosoma mansoni. Seventeen polymeric, 20-amino acids long, peptides comprising the entire Sm31 molecule of the adult worm, were synthesized under the t-boc strategy and their immunogenicity was evaluated. Of these, 10 peptides were immunogenic in rabbits. The peptides containing the sequence Gly74-Ser93 (peptide IMT-172) and the sequence Val154-Ala173 (peptide IMT-180) were responsible for the recognition of the Sm31 molecule by Western blot. This was confirmed by the specific inhibition of recognition of each molecule with the homologous peptide. Additionally, antibodies against these peptides strongly fixed to the adult worm gut. The present results, together with the strong immunogenicity shown for the adult worm 31 kDa antigen, establish the basis for the development of an immunodiagnostic method using synthetic peptides.

Amino Acid Sequence↗

Restricted isotypic antibody reactivity to hepatitis C virus synthetic peptides in immunocompromised patients.

An enzyme immunoassay based on three synthetic peptides from the core, NS4, and NS5 regions of hepatitis C virus allowed the detection of antibodies in 100% of immunocompetent infected patients and in 91% of immunocompromised patients (hemodialysis and hemophiliac patients). Immune impairment seemed to restrict the spectrum of antibody isotypes reacting to the core peptide.

Amino Acid Sequence↗

Proposition of a standard description for phlebotomine sandflies. CIPA Group.

In order to be comparable, and efficient, the descriptions need to be as complete as possible and realized according to the same parameters. In this respect, we present the standard description of Phlebotomine sandflies elaborated by an American network of entomologists in a collaborative program dedicated to the creation of a Computer Aided Identification Program for Phlebotomine Sandflies of South and Central America (CIPA programme).

Animals↗

Ectodermal dysplasia in females and inversion of chromosome 9.

Absence of sweat glands, hypotrichosis, hypodontia, characteristic facial features, and intolerance to heat, without dystrophia of the nails, are manifestations of sex linked hypohydrotic ectodermal dysplasia. Three males and two females were affected in a family in which the affected females were also carrying a pericentric inversion of chromosome 9. Those phenotypically normal females in this pedigree who were obligate carriers had normal karyotypes. One of the affected females (the proband) had, in addition, primary amenorrhoea, absence of the mammary glands, and rudimentary internal genitalia. The fact that clinical manifestations of ectodermal dysplasia in the carrier females of this family are only observed in those also carrying a pericentric inversion of chromosome 9 in peripheral blood leucocytes perhaps suggests that non-random inactivation of the paternal X chromosome has occurred as a consequence of the inversion.

Adolescent↗

Leishmaniasis in the lowlands of Bolivia, prevalence of the disease in two groups of localities with different settlement ages in Carrasco Tropical, Cochabamba.

The invasion of the Bolivian Jungle has brought the new colonists some unfamiliar diseases, among which we study Leishmaniasis. A previous study described the situation in Yapacaní. Departamento of Santa Cruz, a primary rain forest lowland area. We now focus on the characteristics of Carrasco Tropical, close to a hilly territory of the andean mountains. We studied 11 localities ("colonies") grouped as unions with different lengths of residence in the area. We considered males and females over 15 years old as "at risk" and studied in them all forms of leishmanial infection, through clinical and laboratory (smears) means, including the Montenegro Skin Test (IDRM). Cutaneous ulcers and scars were seen in 2.9% (10 patients of 339 at risk, 6 from "27 de octubre", a younger settlement, 4 from the older Tamboradas): mucocutaneous lesions in 3 (1 from the younger settlement); and skin scars alone in 10.3% (35 from the younger area). The only 2 females with positive findings in the study were seen in this latter group. Transmission is apparently associated with the primary forest which exists at the foot of the Andes in the area, which is visited preferentially by young men.

Adolescent↗