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Biomedical subjects

B Rojas

Publications and source records attributed to B Rojas.

At least 19 recordsLinked to original sources
PubMed2006

[Structural changes of the anterior chamber angle in primary congenital glaucoma with respect to normal development].

PURPOSE: To compare findings of normal angles with those from primary congenital glaucoma in order to clarify the pathogenic mechanisms of the disease and to explain the success of surgical treatment in some of these patients. METHODS: Adult normal eyes from cadavers and fragments of surgical trabeculectomies from patients with primary congenital glaucoma previously treated with goniotomy were studied. Eyes were processed for examination using light microscopy and scanning electron microscopy techniques. RESULTS: The following was evident in congenital glaucoma: 1) high iris insertion; 2) no observable pre-trabecular membrane, but enlarged trabeculae with diminished inter-trabecular spaces; 3) Schlemm's canal (SC) apparently normal, with vacuoles in the wall indicating normal functioning; 4) sectioning of the abnormal trabecular tissue during goniotomy allowed repositioning of the angle structures and hence the appearance of the angular recess. CONCLUSIONS: Anomalies of the trabecular structures in primary congenital glaucoma do not always parallel an abnormal development of the SC and the collector channels. This fact could explain the success of goniotomy in this type of glaucoma.

Anterior Chamber↗
PubMed2006

[A comparative study of choroidal innervation in the human and the rabbit (oryctolagus cuniculus)].

OBJECTIVE: To analyze morphological differences between the choroidal innervation of the human and the rabbit, the latter being a species frequently used as an experimental model of human ocular diseases. METHODS: Twelve human and 12 rabbit choroidal whole mounts were processed using an indirect immunohistochemical technique, peroxidase-anti-peroxidase and antibodies against 200 kD neurofilament. RESULTS: Choroidal nerve fibers were perivascular and intervascular. Perivascular fibers surrounded all arteries forming a network that was more developed in the rabbit. In humans, intervascular fibers were mainly concentrated at the posterior pole where they formed a denser and more highly organized plexus than in the rabbit, which did not exhibit a preferential location for these fibers. Human choroidal ganglion cells were far more numerous than in the rabbit and were concentrated in a circumferential area corresponding to the entrance of the short posterior ciliary arteries of the submacular area. In the rabbit, these cells were restricted to the peripheral choroid. CONCLUSIONS: Some differences were observed between human and rabbit choroidal innervation. The abundance of ganglion cells and their preferential distribution could be necessary to maintain a constant blood flow in the central area of the human choroid. The lack of organization of rabbit choroidal innervation at the posterior pole could be associated with an absence of the macula. These differences, along with peculiarities of retinal vascularization, should be taken into consideration when using the rabbit as an experimental model to study human eye diseases in which regulation of choroidal blood flow is involved.

Animals↗
PubMed2005

Cell populations and adhesion molecules expression in conjunctiva before and after bone marrow transplantation.

We were interested to analyse the composition of the cellular infiltrate and adhesion molecules expression in the conjunctiva before and at least one hundred days after autologous and allogenic bone marrow transplantation (BMT) and its relation with the presence of dry eye. We used immunohistochemistry on cryopreserved human conjunctiva with monoclonal antibodies to T-lymphocytes (CD3, CD4 and CD8), B-lymphocytes (CD19), macrophages (CD14), natural killer cells (NK, CD57), intercellular adhesion molecule 1 (ICAM-1), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), lymphocyte function associated antigen-1 (LFA-1), very late antigen-4 (VLA-4), interleukin 2 receptor (IL2r, CD25) and HLA-DR. Our autologous recipients had no graft-versus-host disease (GVHD) but allogenic patients had chronic GVHD. After autologous BMT the conjunctiva had significantly more: (1) T lymphocytes (CD3+, CD4+, CD8+) in the epithelium; (2) CD4+ and CD14+ cells in the stroma; and (3) VLA-4 expression in the stroma than before BMT. After allogenic BMT, the conjunctiva exhibited a significant increase of: (1) CD3+ and CD14+ cells in the epithelium; (2) T lymphocytes (CD3+, CD4+, CD8+) and CD14+ cells in the stroma; and (3) VLA-4 and LFA-1 expression in the stroma than before BMT. After the engraftment, the comparison between autologous and allogenic recipients revealed that: (1) there were no significant differences in adhesion molecule expression; (2) the epithelium of autologous recipients had significantly more CD3+ cells; and (3) the stroma of allogenic patients had significantly more CD3+ and CD8+ cells. Among allogenic recipients, CD14+ cells were significantly increased both in the epithelium and in the stroma of patients with signs or symptoms of dry eye in comparison with patients without ocular involvement. Additionally, those having keratoconjunctivitis sicca (KCS) had CD4/CD8 ratios significantly higher than those without KCS. In conclusion, in the conjunctiva after autologous BMT a subclinical cell mediated immune reaction seems to take place. The conjunctivitis of chronic GVHD is complex, with T cells and macrophages dramatically contributing to the process.

Acute Disease↗
PubMed2005

NPY and TH innervation in human choroidal whole-mounts.

To determine the distribution of NPY and TH human choroidal innervation, choroidal whole-mounts were processed for indirect immunofluorescence. An antibody to a component of the neuronal cytoskeleton, neurofilament 200 kDa (NF-200) was used to identify neurons and axons. A double immunostaining was performed, antibodies against NF-200 being combined with antibodies against neuropeptide Y (NPY) and tyroxine hydroxylase (TH). Fibers containing both NPY and TH were distributed in three plexuses, one in the suprachoroid large-sized vessel layer, and two in the medium-sized vessel layer. Intrinsic choroidal neurons (ICNs) containing NPY and TH were observed in the suprachoroid. The TH(+) ICNs were located in the medium-sized vessel layer. Overall, NPY(+) and TH(+) ICNs were more frequent in the central temporal area, both in isolation and forming microganglia. We also detected small spindle elements intensely immunoreactive to TH(+) and distributed mainly in the suprachoroid from the equator to the periphery. In conclusion, the human choroid contains abundant NPY and TH nerve fibers related to chroroidal vascular structures; it further possesses NPY(+) and TH(+) ICNs which contribute to the choroidal self-regulation persisting after sympathetic denervation. Additionally, these ICNs may at least partially explain why the choroidal blood flow does not respond to the factors that influence systemic vascular control. The preferential location of these cells in the submacular area suggests that dysfunction or degeneration of these cells may be a factor in vascular pathologies found in ocular disease, such as diabetic macular edema or age-related macular degeneration.

Adult↗
PubMed2000

Prenatal diagnosis of total arhinia.

Complete or total arhinia, in which there is absence of the soft tissue of the nose, is extremely rare. The embryological origin of the defect is thought to be maldevelopment of the paired nasal placodes. Available neonatal case descriptions have reported the frequent coexistence of other facial anomalies. This report is the first to describe the antenatal diagnosis of total arhinia confirmed after delivery. Sonographic views of the fetal profile, showing an absence of the nose led to consideration of the diagnosis.

Adult↗
PubMed2000

[Apoptosis in ischemic optic neuropathy].

PURPOSE: A study of human eyes with non-arteritic ischaemic optic neuropathy (NAION) to determine whether there is apoptosis and whether this is accompanied by cell necrosis mechanisms. METHODS: Transmission electron microscopy was used to examine the retinas of eyes with NAION. RESULTS: There was a large number of apoptotic ganglion cells. The lesion was not confined to this retinal layer but also affected the inner nuclear layer, where Müller glia with fagocytic capacity were detected. In this layer apoptosis alternated with necrosis in all of the cell types existing in this level: bipolar cells, amacrine cells and horizontal cells. The outer nuclear layer can also suffer lesion, essentially by induction of choroid ischaemia to that level. Again, apoptosis was observed at the photoreceptor level, where there was also death by heterophagy, although this was less frequent. CONCLUSIONS: The behaviour of NAION in humans is similar to that found in experimental models. Apoptosis mechanisms develop, alternating with cell necrosis in the nuclear level.

Aged↗
PubMed1999

pH and drug resistance. I. Functional expression of plasmalemmal V-type H+-ATPase in drug-resistant human breast carcinoma cell lines.

A major obstacle for the effective treatment of cancer is the phenomenon of multidrug resistance (MDR) exhibited by many tumor cells. Many, but not all, MDR cells exhibit membrane-associated P-glycoprotein (P-gp), a drug efflux pump. However, most mechanisms of MDR are complex, employing P-gp in combination with other, ill-defined activities. Altered cytosolic pH (pHi) has been implicated to play a role in drug resistance. In the current study, we investigated mechanisms of pHi regulation in drug-sensitive (MCF-7/S) and drug-resistant human breast cancer cells. Of the drug-resistant lines, one contained P-gp (MCF-7/DOX; also referred to as MCF-7/D40) and one did not (MCF-7/MITOX). The resting steady-state pHi was similar in the three cell lines. In addition, in all the cell lines, HCO3- slightly acidified pHi and increased the rates of pHi recovery after an acid load, indicating the presence of anion exchanger (AE) activity. These data indicate that neither Na+/H+ exchange nor AE is differentially expressed in these cell lines. The presence of plasma membrane vacuolar-type H+-ATPase (pmV-ATPase) activity in these cell lines was then investigated. In the absence of Na+ and HCO3-, MCF-7/S cells did not recover from acid loads, whereas MCF-7/MITOX and MCF-7/DOX cells did. Furthermore, recovery of pHi was inhibited by bafilomycin A1 and NBD-Cl, potent V-ATPase inhibitors. Attempts to localize V-ATPase immunocytochemically at the plasma membranes of these cells were unsuccessful, indicating that V-ATPase is not statically resident at the plasma membrane. Consistent with this was the observation that release of endosomally trapped dextran was more rapid in the drug-resistant, compared with the drug-sensitive cells. Furthermore, the drug-resistant cells entrapped doxorubicin into intracellular vesicles whereas the drug-sensitive cells did not. Hence, it is hypothesized that the measured pmV-ATPase activity in the drug-resistant cells is a consequence of rapid endomembrane turnover. The potential impact of this behavior on drug resistance is examined in a companion manuscript.

Antineoplastic Agents↗
PubMed1999

Intraocular lens removal from [corrected] patients with uveitis.

PURPOSE: To report a series of patients with uveitis and cataract who had undergone cataract extraction with posterior chamber intraocular lens implantation and who subsequently had the intraocular lens removed because of progressive intraocular damage from inflammation. METHODS: Review of the records of 19 patients after removal of a posterior chamber intraocular lens. The decision to perform surgery was based on standard criteria after evaluation at a single uveitis referral center. RESULTS: The complications leading to intraocular lens removal were perilental membrane (eight eyes), chronic low-grade inflammation not responding to anti-inflammatory treatment (eight eyes), and cyclitic membrane resulting in hypotony and maculopathy (three eyes). After intraocular lens removal the inflammation subsided and the visual acuity improved or stabilized in 14 of the 19 eyes. The causes of further reduction in the visual acuity of the other five patients were macular edema (two patients), maculopathy resulting from hypotony (one patient), retinal detachment (one patient), and vitreous hemorrhage (one patient). CONCLUSIONS: Intraocular lens implantation can form part of a reasonable plan for visual rehabilitation of patients with uveitic cataract, but inclusion of an intraocular lens in the plan is not always in the overall long-term best interest of the patient. Intraocular lens removal may salvage useful vision for patients who continue to exhibit complications secondary to uveitis after cataract extraction and intraocular lens implantation, provided the intraocular lens is removed before irreparable damage has been done to macula or optic nerve.

Acute Disease↗
PubMed1999

Medical treatment of macular edema in patients with uveitis.

PURPOSE: To determine the efficacy of medical treatment of cystoid macular edema (CME) in patients with uveitis. METHODS: Retrospective study of 40 patients (57 eyes) with uveitis and CME. Inclusion criteria were presence of CME with minimal and no macular pathology, or vascular disease which could account for CME. Patients who had undergone intraocular surgery or had visual acuity (VA) of > or = 20/40 were excluded. The diagnosis of CME was based on clinical and/or angiographic findings. Three treatment groups were defined: (1) transseptal injection of steroids (n=13 eyes); (2) systemic non steroidal anti-inflammatory drugs (NSAIDs) (n=11 eyes); both 1 and 2 (n=33 eyes). RESULTS: Overall, 79% of eyes improved 3 or more lines of Snellen VA after treatment: 51% improved 4 or more lines. The average number of lines improved was 3.8 for eyes treated with transseptal injections of steroids, 2.9 for eyes treated with NSAIDs, and 4 for eyes treated with both. For all 3 treatment groups between 60-70% of eyes improving 2 or more lines reached best VA only after a minimum of 6 months of follow up. CONCLUSIONS: CME, a vision threatening complication of uveitis, respond fairly well to medical treatment; however, the best VA is achieved after several months. The improvement in VA did not differ markedly among the three treatment groups.

Adolescent↗
PubMed1998

Costimulatory molecules in ocular cicatricial pemphigoid.

PURPOSE: To examine normal and inflamed conjunctiva from patients with ocular cicatricial pemphigoid (OCP) for the presence of costimulatory molecule CD28 and its ligands B7-1 (CD80) and B7-2 (CD86). METHODS: Conjunctival biopsy specimens from 12 patients with OCP and from five healthy persons undergoing cataract surgery were analyzed by light microscopy and immunohistochemical examination with monoclonal antibody probes for CD28, B7-1, and B7-2 molecules and for mononuclear cell subtypes. RESULTS: Epithelium of OCP conjunctiva showed more Langerhans' cells, B7-1-positive (+) cells, and B7-2 expression (ratio of B7-2-positive cells to antigen-presenting cells). In the substantia propria, OCP specimens showed significantly increased numbers of T cells (CD3 +), macrophages (CD68+), CD28+ cells, B7-2+ cells (CD86+), Langerhans' cells (CD1a), and B7-1+ cells (CD80). Most of the B7-2+ cells, macrophages, and Langerhans' cells were located subepithelially. B7-2 expression was significantly higher in OCP conjunctival substantia propria compared with normal conjunctiva. CONCLUSIONS: The results of this study indicate that the expression of the costimulatory molecule B7-2 is upregulated in conjunctiva of patients with active OCP. This increased subepithelial B7-2 expression may contribute to the sustained immune activation in OCP conjunctiva.

Antibodies, Monoclonal↗
PubMed1998

[Priapism in a patient with chronic myeloid leukemia].

Priapism is a rare complication of hematological diseases. Among leukemia, it is most frequently seen in patients with chronic myeloid leukemia, due to the high leukocyte counts that these patients achieve. We report a 22 years old male who presented with a priapism lasting more than 24 hours. Thirty six hours after admission and subsequent to a leukopheresis, penile relaxation was obtained. Despite good hematological response to therapy, an extensive penile and uretral necrosis, associated to an Acinetobacter infection, ensued between the fourth and fifth day of admission, that required surgical treatment.

Adult↗
PubMed1997

Electrocortical and behavioral responses produced by acute electrical stimulation of the human centromedian thalamic nucleus.

Incremental, desynchronizing and spike-wave electrocortical responses and concomitant symptoms to acute electrical stimulation of the centromedian thalamic nucleus (CM) were studied in 12 patients with intractable complex partial and tonic-clonic generalized seizures. Low-frequency (6/s), 320-800 microA stimulation of the caudal-basal and central portions of CM elicited incremental recruiting and augmenting-like responses with a bilateral regional scalp distribution, with emphasis at the ipsilateral frontal (recruiting) and central (augmenting) regions, while ventral-basal CM stimulation elicited primary-like responses with a focal distribution at the ipsilateral parietal region. High-frequency (60/s), 320-800 microA stimulation of caudal-basal and central, but not ventral-basal CM, elicited EEG desynchronization and a slow negative shift of the EEG baseline with scalp distribution similar to that showed by recruiting- and augmenting-like responses. Neither incremental nor desynchronization EEG responses were accompanied by evident patient sensory or motor responses. Low-frequency (3/s), high-intensity (30 V = 2400 microA) combined stimulation of the right CM and left non-specific mesencephalic ascending pathways elicited a response similar to the typical absence attack with all EEG and clinical ingredients: S1, S2, P1 and W components of the individual spike-wave complex and generalized spike-wave discharges followed by sleep spindle EEG afterdischarges, accompanied by motionless stare, 3/s eye blinking, lip smacking and total failure to respond to visual stimuli in patients under a simple responding task.

Behavior↗
PubMed1997

Cataract surgery in patients with uveitis.

Although cataract surgery for senile cataract is routine and easily performed, the decision to remove the cataract in a patient with a history of uveitis is considerably more complex and usually involves multiple considerations, related not only to the cause of the uveitis but also to the appropriate surgical procedures. The problems confronting the ophthalmologist caring for the patient with uveitis begin with the first visit. Establishing a diagnosis and controlling the inflammation are the critical elements in the treatment of the patient; these two factors will determine the incidence of cataract formation and other complications, the appropriate time for cataract removal, and the surgical strategy, as well as determine the visual outcome long before surgery occurs. Diagnosis, control of inflammation, preoperative management, particularities of the surgical techniques, and postoperative complications in patients with a history of uveitis have been reviewed previously in this section. Our aims in this article are to review the literature on this subject over the past year and to reemphasize the idea of a model of zero tolerance for inflammation to minimize the incidence of cataract and irreversible damage of ocular structures essential to good vision.

Cataract↗
PubMed1997

[Acute myeloid leukemia MO: clinical and laboratory characteristics].

BACKGROUND: A recent update of FAB classification has included a myeloid leukemia subtype with a minimal degree of differentiation, that has been denominated LMA-MO. AIM: To report the clinical, morphological and immunophenotypic features of patients with LMA-MO. PATIENTS AND METHODS: Eight patients, out of 368, with acute myeloid leukemia that were studied in the Hematology Laboratory of a public hospital in Santiago, were classified as LMA-MO. RESULTS: Blast cell morphology was undifferentiated or of subtype FAB-L2 lymphoblastic leukemia with medium sized blasts, agranular basophilic cytoplasm, reticular nuclear chromatin and a prominent nucleolus. Cytochemical staining was negative for peroxidase and esterases, immunophenotyping showed the expression of one or more myeloid antigens (CD13, CD33) and was negative for lymphoid antigens. Immunocytochemical expression of myeloperoxidase was positive in the three cases where it was performed. Only one patient achieved complete remission and is free of disease after 36 months of follow up. All other patients died without obtaining remission, six shortly after the onset and one 12 months after. CONCLUSIONS: The diagnosis of LMA-MO is essential considering its dismal prognosis.

Acute Disease↗
PubMed1996

Cataract surgery in patients with uveitis.

Until recently, cataract surgery in a patient with uveitis was regarded as a hazardous procedure that yielded unpredictable and often disappointing results. With an increasing number of ophthalmologists recognizing the consequences of chronic low-grade inflammation and therefore treating uveitis patients more aggressively, with a better selection of cases for surgery, and with better surgical techniques, more patients with a history of uveitis who need cataract surgery enjoy a successful outcome than ever before. Careful management and control of inflammation preoperatively and after surgery is critical to success. An in-the-bag posterior chamber lens implant can be part of the surgical plan in selected cases. The aims of the authors in this article are to emphasize the ideas of, intolerance to inflammation, a limited tolerance for steroids to minimize the incidence of cataract and irreversible damage of ocular structures essential to good vision, and strict criteria for selection and management of those patients with uveitis who need cataract surgery.

Cataract↗
PubMed1995

Myoplasmic Ca2+ concentration during exertional rhabdomyolysis.

Exertional rhabdomyolysis can destroy muscle but the pathophysiology is unknown. Using intracellular selective microelectrodes, we found that intracellular Ca2+ concentration ([Ca2+]i) was 1.27 (0.17) mumol/L (median and interquartile range) in skeletal-muscle biopsy specimens from patients with exertional rhabdomyolysis compared with 0.12 (0.01) mumol/L in controls. 3 days treatment with dantrolene, a drug that inhibits Ca2+ release from the sarcoplasmic reticulum, decreased [Ca2+]i to 0.22 (0.05) mumol/L and accelerated patients' recovery. This study demonstrated that exertional rhabdomyolysis is associated with elevated [Ca2+]i, and that dantrolene has a beneficial effect in this syndrome.

Adult↗
PubMed1989

[Patients with primary anterior uveitis. Determination of circulating immune complexes].

The level of circulating immune complexes (CIC) in 31 patients with primary anterior uveitis was determined by an ELISA method (C1q in solid phase). In addition, we measured antinuclear antibodies (ANA), HLAB 27, C3 and C4. Increased levels of CIC were found in 38% of patients (Group I), the remainder had normal levels (Group II). Positive ANA were found in 33% of patients in Group I and 26% of patients in Group II. The clinical findings and course of uveitis was similar in both groups. Chronic uveitis was associated to greater levels of CIC as compared to recurrent uveitis among patients in Group I (p less than 0.0001). Also, moderate sequelae from uveitis were associated to higher CIC levels.

Adolescent↗