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Biomedical subjects

M E Rojas

Publications and source records attributed to M E Rojas.

10 recordsLinked to original sources
PubMed2006

Infectious haemolytic anaemia causes jaundice outbreaks in seawater-cultured coho salmon, Oncorhynchus kisutch (Walbaum), in Chile.

In the last 9 years, epizootics of an icterus condition has affected coho salmon, Oncorhynchus kisutch (Walbaum), reared in seawater cages in southern regions of Chile. At necropsy, fish from field cases exhibited signs of jaundice accompanied by pale light-brown livers and dark spleens. Histopathological and haematological results indicated that these fish presented haemolytic anaemia. After microbiological examination no bacterial or viral agents could be identified as aetiological agents of this disease. In an infectivity trial, coho salmon, Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), were inoculated intraperitoneally with a filtrate of an organ homogenate (0.45 microm) from a diseased coho salmon and held for 60 days in tanks supplied with fresh water. The disease was only reproduced in coho salmon in which mortalities, beginning at day 23 post-inoculation (p.i.), reached a cumulative value of 24% at day 27 p.i. This condition was transmitted to non-inoculated cohabiting coho salmon suggesting that it is a waterborne disease. Thus, this icteric condition is caused by an infectious form of haemolytic anaemia, probably of viral aetiology, and coho salmon are more susceptible than either Atlantic salmon or rainbow trout.

Anemia, Hemolytic↗
PubMed2004

Experimental infection of coho salmon Oncorhynchus kisutch by exposure of skin, gills and intestine with Piscirickettsia salmonis.

Piscirickettsiosis pathogenesis was examined using some tissues as entry portals of Piscirickettsia salmonis in coho salmon. Juvenile fish, weighing approximately 8.4 g, were used in this trial. Inocula were prepared using the strain SLGO-95 of P. salmonis. The micro-organism was cultured in the CHSE-214 cell line as described by Fryer et al. (1990) and doses containing 10(4.7) and 10(3.7) TCID50 were prepared. Each dose was used to infect the fish via skin, gills and intestine. Skin and gills were exposed by calibrated drops, and the intestine by an intubation through the anal opening. Some fish were injected intraperitoneally with the same P. salmonis doses, as positive virulence controls. Sham-inoculated fish for each of the tested routes were also included as negative controls. Piscirickettsiosis was experimentally reproduced with all the inoculation methods. Cumulative mortalities and survival analyses showed that the most effective entry portal was skin followed by intestinal intubation and finally by gill infection.

Animals↗
PubMed1998

Colorectal sarcoma: analysis of failure patterns.

BACKGROUND AND OBJECTIVES: Colorectal sarcomas (CRS) are rare and their treatment remains controversial, especially for those located in the rectum. The aim of this paper is to evaluate our experience, with special emphasis on the failure pattern after surgical therapy alone or combined with postoperative radiotherapy. MATERIALS AND METHODS: The medical records and histological slides of 13 CRS patients treated between 1986 and 1996 were reviewed retrospectively. RESULTS: The patients included eight males and five females, with a median age of 54 years; nine of their primary tumors were located in the rectum, and four in the colon. The histologies were leiomyosarcoma in nine cases and malignant fibrous histiocytoma in four cases. Surgical treatment consisted of anatomical colectomy (four); local excision (three); abdominoperineal resection (APR)(two); low anterior resection (LAR)(two); LAR en bloc with the prostate (one), and total pelvic exenteration (one). One operative death occurred. The median size of the tumors was 8 cm (range, 5-40). The tumors were graded as low, three, and high, ten. The median follow-up was 24 months. Eight patients in the overall group developed recurrences as follows: local, three; local and distant, three, and distant, two. Five out of nine patients with rectal sarcoma received adjuvant postoperative radiotherapy (PRT). Local recurrence occurred in 20% (1/5) of those who received PRT, and in 100% (3/3) of those who did not. The overall 5-year survival was 40%, and the 5-year survival for patients with low-grade tumors was 66%, as compared with 22% for those with high-grade tumors. CONCLUSIONS: The patterns of failure in CRS are combined in both local and distant sites. However, our results suggest that in rectal sarcoma, the use of surgery + PRT may reduce the local recurrence rate; in selected patients, it may allow for anal sphincter preservation.

Adult↗
PubMed1995

Functional mapping of the surface residues of human thrombin.

Utilizing site-directed mutagenesis, 77 charged and polar residues that are highly exposed on the surface of human thrombin were systematically substituted with alanine. Functional assays using thrombin mutants identified residues that were required for the recognition and cleavage of the procoagulant substrate fibrinogen (Lys21, Trp50, Lys52, Asn53 + Thr55, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Asp193 + Lys196, Glu202, Glu229, Arg233, Asp234) and the anticoagulant substrate protein C (Lys21, Trp50, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Glu229, Arg233), interactions with the cofactor thrombomodulin (Gln24, Arg70) and inhibition by the thrombin aptamer, an oligonucleotide-based thrombin inhibitor (Lys65, His66, Arg70, Tyr71, Arg73). Although there is considerable overlap between the functional epitopes, distinct and specific residues with unique functions were identified. When the functional residues were mapped on the surface of thrombin, they were located on a single hemisphere of thrombin that included both the active site cleft and the highly basic exosite 1. No functional residues were located on the opposite face of thrombin. Residues with procoagulant or anticoagulant functions were not spatially separated but interdigitated with residues of opposite or shared function. Thus thrombin utilizes the same general surface for substrate recognition regardless of substrate function although the critical contact residues may vary.

Amino Acid Sequence↗
PubMed1995

Plasmacytoid myoepithelioma of the laryngeal region: a case report.

The first case of plasmacytoid myoepithelioma of the laryngeal region is presented. The tumor showed immunoreactivity for the S-100 protein, low molecular weight cytokeratin, and vimentin. Staining was negative with muscular actin and glial fibrillar acid protein. By electron microscopy the tumor cells showed abundant microfibrillar material, elongated densities resembling smooth muscle dense bodies, pinocytic vesicles, and replicated basal lamina. The myoepithelial nature of plasmacytoid tumors of the salivary gland has been questioned.

Female↗
PubMed1993

Serum levels of tumor necrosis factor in patients with American cutaneous leishmaniasis.

The purpose of this study was to evaluate serum levels of TNF-alpha in patients with either of the three clinical forms of American cutaneous leishmaniasis. The 86 patients examined were classified as having either the localized (LCL: 22 patients), mucocutaneous (MCL: 45 patients), or the rare diffuse (DCL: 19 patients) form of the disease. Our results show a significant increase in the mean level of TNF-alpha in the three groups of patients when compared to controls. MCL patients produce significantly higher levels of TNF-alpha than DCL patients. The proportion of individuals positive for serum TNF-alpha was significantly higher in both MCL and DCL patients than in the controls. No significant differences were found in the level of TNF-alpha when compared between before and after cure of 12 patients with MCL. There were no significant correlations between the level of TNF-alpha and the skin test diameter. The results will be discussed in terms of the pathogenesis of the disease in its different clinical forms.

Adolescent↗
PubMed1992

Evaluation of serum levels of tumour necrosis factor-alpha (TNF-alpha) and soluble IL-2 receptor (sIL-2R) and CD4, CD8 and natural killer (NK) populations during infrared pulsed laser device (IPLD) treatment.

The purpose of this study was to evaluate serum levels of TNF-alpha, sIL-2R and distribution of peripheral leucocyte subsets in patients with advanced neoplastic disease undergoing IPLD treatment. Fifteen cancer patients with evidence of persistent disease were further divided in two groups according to outcome at the end of the period of clinical evaluation: group 1 patients were still alive and group 2 patients had died. Our results show: (i) an increase in the initial level of TNF-alpha in both groups; (ii) a decrease in TNF-alpha levels during the follow up of group 1 patients; (iii) a significant increase in serum levels of sIL-2R in patients in group 2 compared with those in group 1; (iv) a progressive and constant increase in TNF-alpha levels in group 2; (v) a decrease in CD4+CD45RA+ subpopulation in both groups; (vi) an increase in CD25+ cells; (vii) an increase in CD4+, CD4+CD45RA+ and CD25+ cells during the follow up of group 2 patients. The data generated here form the basis for further investigations on the use of IPLD as a single agent and in combination with other biological response modifiers in cancer patients.

Antigens, CD↗
PubMedDate not supplied

Early hospital discharge of preterm very low birth weight infants.

OBJECTIVE: The objective of this study was to investigate whether early discharge from the hospital was feasible for selected very low birth weight (VLBW) infants. STUDY DESIGN: A randomized clinical trial of discharge of VLBW infants from the neonatal intensive care unit at 1300 gm versus 1800 gm was done comparing weight gain and incidence of infection. Forty-three VLBW infants treated in the neonatal intensive care unit and follow-up clinics of the Hospital Universitario del Valle, Cali, Colombia, were entered into the study at 1300 to 1350 gm when they met behavioral criteria for discharge and the family home was approved. RESULTS: There were no differences in weight gain or incidence of infection in the home group compared with the hospital group. A significant saving in hospital days and hospital costs was realized for the home group. Family cooperation was heightened in the home group. CONCLUSIONS: Early discharge from the hospital at weights as low as 1300 to 1350 gm is safe for the VLBW infant when properly selected on the basis of behavioral criteria and environmental approval. The potential savings in hospital costs should be considered when resources are allocated for continued support for these infants.

Age Distribution↗