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Biomedical subjects

A Hernando

Publications and source records attributed to A Hernando.

At least 19 recordsLinked to original sources
PubMed2000

[Influence of a day care hospital on the incidence of hospital admission of AIDS patients].

BACKGROUND: Day care units have become an usual way of medical care for AIDS patients. However, their influence on the incidence of hospital admissions has not been evaluated. METHODS: Observational and longitudinal study of a cohort of 308 patients with aids diagnosed between 1990 and 1994 and followed-up to June 1996. The incidence of hospital admissions according to the hospital of follow-up (with or without day care unit) was analyzed. A multivariate analysis of the number of hospital admissions was performed using regression model adjusted to a distribution of Poisson. RESULTS: After AIDS diagnosis, the incidence of hospital admissions was 108 per 100 patient-years of follow up (21 days as inpatient per patient-year). Those patients controlled in the hospital with day care unit have less hospital admissions (relative risk after adjusting by CD4+ cells count and type of diagnostic disease: 0.64; CI95% 0.55-0.76), and less days as inpatient through their follow-up (11 to 31 days less). There was no difference in survival among patients followed in both hospitals. CONCLUSIONS: A day care unit decrease the incidence of hospital admissions in aids patients. This positive impact is more evident in patients with lesser CD4+ cell counts.

Acquired Immunodeficiency Syndrome↗
PubMed1998

[Comparison of chemotherapy CHOP vs. CHOP/VIA in the treatment of aggressive non-Hodgkin's lymphoma: a randomized multicenter study of 132 patients. The PETHEMA group. Program for Study and Therapeutics of malignant hemopathies. Spanish Association of Hematology and Hemotherapy].

BACKGROUND: To compare standard chemotherapy CHOP (cyclophosphamide, adriamycin, vincristine and prednisone) with the regimen CHOP/VIA (VP-16, iphosphamide and cytarabine) in terms of response to therapy, response duration, survival and toxicity in patients with aggressive lymphoma. PATIENTS AND METHODS: 132 patients (84 males and 48 females; median age, 55 years) were included from 12 Spanish Institutions, diagnosed of non-Hodgkin's lymphoma of intermediate or high grade, in stages II-IV and previously untreated. Patients were randomized to receive CHOP or CHOP/VIA. RESULTS: After excluding 14 not assessable cases, 62 patients (52.5%) received CHOP, and 56 (47.5%) CHOP/VIA. No significant differences were found on main prognostic factors between such groups. Response was assessable in 114 cases (CHOP: 61; CHOP/VIA: 53) 39 patients (64%) receiving CHOP achieved complete response (CR), and 2 (3%) partial response (PR), whereas in the CHOP/VIA group CR and PR rates were 63% (34/53), and 7% (4/53), respectively. 14 patients (36%) treated with CHOP and 12 (35%) treated with CHOP/VIA eventually relapsed, with an actuarial risk of relapse at 36 months of 43% and 40%, respectively. Median survival was 37 months. No differences were found between both therapeutic groups, with an overall survival at 36 months from diagnosis of 53.5% (CI 95%: 40-67) for CHOP and 48% (CI 95%: 34-62) for CHOP/VIA. Finally, toxicity was not different for both arms. CONCLUSION: In the present study in patients with aggressive NHL chemotherapy regimens CHOP and CHOP/VIA showed similar results in terms of response, response duration, survival and toxicity.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Long-term evaluation of the behavior of a polytetrafluoroethylene microprosthesis in the rat iliac artery: myointimal regression.

The present study represents a long-term investigation of polytetrafluoroethylene (PTFE) vascular microprostheses implanted in the right common iliac artery of rats, with the aim of evaluating the degree of intimal hyperplasia and the changes produced in the vascular prosthesis. A follow-up study was performed between 3 months and 1 year post-implantation, using immunohistochemical techniques, light, and electron microscopy. Three months after implantation, the PTFE segment appeared sandwiched between two cell layers. A general endothelialization was observed on the luminal surface. The underlying myointima appeared as an irregular lining of decreasing thickness, from the distal anastomosis with the receptor artery to the proximal suture. A large number of white blood cells were found adherent to and infiltrating the endothelium. A neoformed adventitia covered the prosthesis on the external surface. At 4 months post-implantation, a destabilization of the luminal surface was observed induced by white blood cells. A progressive reduction in the thickness of the myointimal layer was also apparent, so that 1 year after implantation, the luminal surface of the PTFE prosthesis was fully lined by a thin cell covering. There is good long-term tolerance to implanted PTFE microprostheses. The white blood cells present in the implant region appeared to play an important role in the long-term regression of intimal hyperplasia.

Animals↗
PubMed1996

Similarity in behavior of polytetrafluoroethylene (ePTFE) prostheses implanted into different interfaces.

The biomaterial ePTFE is widely used in the clinical environment for vascular replacement or bypass, as well as in the repair of tissue defects, especially those involving the abdominal wall. The objective of this study was to evaluate the healing response to ePTFE prostheses implanted into a circulatory interface and a tissue interface, each in a different animal species. For vascular implants, the Sprague-Dawley rat (n = 60) was used, while the New Zealand white rabbit (n = 20) was used in the tissue replacement model. In the former, a vascular microprosthesis measuring 5 mm in length and 1 mm in internal diameter, having a porosity of 30 microns, was implanted into the common iliac artery. In the rabbit, a 7 x 5-cm fragment of ePTFE (Soft-Tissue Patch) was implanted into a defect in anterior abdominal wall that involved all the tissue layers. In this case, the prosthesis was left touching the intestinal loops. The implants were studied between 14 and 90 days of postimplantation by means of light microscopy, scanning electron microscopy, and immunohistochemistry. The latter involved the use of anti-rat (MAC-341) and anti-rabbit (RAM-11) macrophage-specific monoclonal antibodies. The behavior of the ePTFE in the different interfaces (vascular and abdominal wall) was similar with respect to the following aspects: the prosthesis presented a process of encapsulation which was more intense on the outer surface; colonization of the implant was limited to the outermost two thirds, with minimal invasion of the middle portion; colonization was absent on the edges of the prosthesis; collagenization of the interstice of the mesh occurred late; the foreign body reaction taking place on the outer surface was similar in both interfaces, with formation of a barrier consisting of macrophages and giant cells that did not penetrate the prosthesis; and, finally, in neither of the two models was vascular colonization of the PTFE prosthesis observed; rather, the angiogenic process was limited to the periprosthetic zones. The integration of the implant made of ePTFE is similar despite the differences in interfaces and the use of different animal species. The macrophage response does not determine the success or failure of the implant.

Abdominal Muscles↗
PubMed1996

Improvement of the tissue integration of a new modified polytetrafluoroethylene prosthesis: Mycro Mesh.

We studied the behaviour of the different tissue interfaces formed on a new type of prosthesis used for the repair of abdominal wall defects, Mycro Mesh (W. L. Gore and Ass., Flagstaff, AZ, USA), which consists of perforated layers of polytetrafluoroethylene (PTFE). In 20 New Zealand white rabbits, a full-thickness (except skin) 7 cm x 5 cm defect was created in the anterior abdominal wall. The defects were repaired with a prosthetic implant (Mycro Mesh) that was placed in direct contact with abdominal viscera and subcutaneous tissue. At 14, 30, 60 and 90 d post-implantation, samples were obtained from the tissue interfaces formed between the prosthesis and subcutaneous tissue, visceral peritoneum and receptor tissue, respectively. Samples were studied by optical microscopy and scanning electron microscopy. The immunohistological study was made with RAM-11, a monoclonal antibody specific for rabbit macrophages. Tensile strength was measured with an Instron tensiometer using 2 cm wide strips obtained parallel to the shorter axis of the implant. Strips included the prosthesis and two anchor zones on the receptor tissue. Macroscopically, the prosthesis induced little adhesion formation on the visceral peritoneum interface. Microscopically, an organized neoperitoneum and abundant tissue formed on the subcutaneous interface. In the prosthesis perforations, bridges of tissue linked the peritoneal and subcutaneous sides. The macrophage response decreased significantly in intensity between day 14 and day 90 (Student-Newman-Keuls test, P = 0.01). Tensile strength increased significantly (Wilcoxon test, P < 0.05) at every study period. To conclude: the Mycro Mesh prosthesis proved suitable for implantation in sites where it comes in contact with abdominal viscera and it provided good support for the formation of an organized neoperitoneum; the perforations in the prosthetic material improved implant integration; the macrophage response was not altered by the biomaterial and the tensile strength of the prosthesis increased as scar tissue formation and tissular integration of the prosthesis progressed.

Abdominal Muscles↗
PubMed1996

Inhibitor of angiotensin-converting enzyme modifies myointimal origin in an arterial autograft model.

Pharmacologic modulation by an inhibitor of angiotensin-converting enzyme (IACE: cilazapril) of vascular proliferative response to a full-thickness arterial injury (autograft) was studied in rats. An arterial autograft 5 mm long was made in the right common iliac artery of 50 female Sprague-Dawley rats (weight 250-300 g) by microsurgical techniques. The animals were divided into two study groups: group I (controls), 20 animals that underwent arterial autograft but received no other treatment; and group II (cilazapril-treated), 20 rats that underwent arterial autograft and received cilazapril (Roche), 10 mg/day orally (p.o.) in an excipient of 2% arabic gum, for 4 days before operation. Animals were killed on postoperative days 7, 14, 21, 30, and 50, and grafts were studied by light microscopy, scanning and transmission electron microscopy, and morphometry. In the control group, the hyperplasic response had begun by postoperative day 14 and was established by postoperative day 50. In the medial layer, the muscle cells changed in phenotype from contractile to secretory cells. The adventitia had a highly proliferative appearance. In the cilazapril-treated group, fibrin deposits and platelets formed a layer on the internal elastic lamina. This layer appeared to evolve toward an intimal hyperplasia that became quantifiable by postoperative day 21. The medial layer was clearly thinned and showed intense accumulation of lipid microvacuoles, elastic degeneration, and vacuolized cells. Our results suggest that the use of an inhibitor of ACE modified the origin of the intimal hyperplasia in the arterial autograft model. Enhancement of the thrombogenicity of the luminal surface favors myointimal development by thrombus reorganization.

Angiotensin-Converting Enzyme Inhibitors↗