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Biomedical subjects

A Rodriguez

Publications and source records attributed to A Rodriguez.

At least 91 records · Page 5Linked to original sources
PubMed1992

Retinal detachment after refractive surgery for myopia.

Refractive surgery has been used widely in some countries for the last 20 years for the correction of myopia. Radial keratotomy and keratomileusis, the most common procedures, may concur with retinal detachment. A total of 14 eyes in 12 patients, 7 after keratomileusis and 7 after radial keratotomy, which had either asymptomatic or symptomatic retinal breaks, subclinical and clinical rhegmatogenous retinal detachments, or both, are discussed here. Five eyes were treated with either laser photocoagulation or cryopexy alone, seven eyes with a scleral buckling procedure, one eye with vitrectomy, and one eye was not operated on. At the final follow-up examination, anatomic reattachment had been achieved in 12 of 14 eyes (85.7%). Visual acuity improved in 3 eyes (21.4%), remained stable in 9 eyes (64.3%), and was worse in 2 eyes (14.3%). The scleral buckling procedures used in the repair of retinal detachment induced refractive changes by modifying axial length and corneal curvature, with recurrence of myopia and astigmatism. Myopia increased a mean of -3.00 diopters in 6 of 7 eyes (86%). Myopic astigmatism power changed a mean of -1.00 diopter in 5 eyes (71%), and the astigmatic axes shifted in 3 eyes (43%). This situation could be prevented with an early peripheral search for and treatment of peripheral retinal degenerative pathologic changes, by avoiding encircling bucklings, or by using alternative methods of treatment.

Adult↗
PubMed1992

Discriminative criteria for Neisseria meningitidis isolates that are moderately susceptible to penicillin and ampicillin.

The prevalence of Neisseria meningitidis isolates that are moderately susceptible to penicillin and ampicillin has increased very quickly in Spain; the current prevalences in our hospital are 48.4 and 55.6%, respectively. We studied the reliability of the disk diffusion method for discriminating between fully susceptible (MIC, less than or equal to 0.06 microgram/ml) and moderately susceptible (MICs, 0.12 to 1.0 microgram/ml) isolates. Thirty-eight isolates (12 Pen(s) Amp(s), 18 Penr Ampr, and 8 Pen(s) Ampr) were assayed by the disk diffusion and plate dilution methods by use of disks of 1, 2, 5, and 10 U of penicillin, 2 and 10 micrograms of ampicillin, and 1 microgram of oxacillin on Mueller-Hinton agar with or without 5% sheep blood. Breakpoints were generated, and their discriminative values were determined with a collection of 195 meningococcal strains isolated consecutively from cerebrospinal fluid or blood. None of the strains produced beta-lactamase. Penicillin- and ampicillin-susceptible strains (MIC, less than or equal to 0.06 microgram/ml) had oxacillin inhibition zones of greater than or equal to 11 mm on blood agar. Moderate susceptibility to ampicillin and penicillin was suggested by an inhibition zone of less than or equal to 10 mm around the 1-microgram disk and an inhibition zone of less than or equal to 26 mm around the 2-U penicillin disk. We conclude that discrimination between fully susceptible and moderately susceptible populations of N. meningitidis can be accomplished by the disk diffusion method by use of Mueller-Hinton agar plus 5% sheep blood with the 1-microgram oxacillin disk (which is especially suited for screening methods) and the 2-U penicillin disk. The lack of an oxacillin inhibition zone indicates moderate susceptibility to either penicillin or ampicillin or both.

Ampicillin↗
PubMed1992

Aromatase activity and estradiol in human breast cancer: its relationship to estradiol and epidermal growth factor receptors and to tumor-node-metastasis staging.

PURPOSE: The present report attempts to clarify whether there is a relationship between aromatase activity (ARAC) and estradiol (E2), hormonal receptors, E2 receptor (ER), and epidermal growth factor receptor (EGFR), as well as with tumor stage and histopathology in human breast cancers. MATERIALS AND METHODS: We studied 225 breast carcinomas, 67 of which were premenopausal and 158 postmenopausal. In each sample, ARAC, EGFR, ER, and E2 were quantified. ARAC was quantified by Thompson and Siiterii's method, EGFR was quantified with a two-point assay method using radioactive iodine (125I)-EGF as ligand, and ER was measured by the Scatchard method using 3H-E2. E2 was quantified by radioimmunoassay in the diethylether tumor extract. RESULTS: ARAC was found in 64% of the cancers studied. There is a strong direct association between ARAC and tumor size in postmenopausal patients (P = .001). In the postmenopausal group, the proportion of ARAC-positive (ARAC+) tumors is significantly higher among ER-positive (ER+) than ER-negative (ER-) ones (P less than .001). ER+ tumors also have significantly higher levels of E2 than do ER- ones (P less than .0001); similarly, ARAC+ tumors have significantly higher levels of E2 than do ARAC- ones (P less than .0001). There is a significant multiple linear correlation between the log of the levels of ARAC, ER, and EGFR and the log of tumor E2 (P less than .0001). The correlation coefficients obtained show that ARAC and ER have a positive effect on tumor E2. CONCLUSION: The results obtained suggest the importance of tumor ARAC in the tumoral levels of E2 and reinforce the possible biologic significance of tumor ARAC, especially in postmenopausal breast carcinoma patients.

Adult↗
PubMed1992

Suppressive effect of tetrahydrocannabinol on specific T cell subpopulations in the thymus.

The effects of THC (delta-9-tetrahydrocannabinol) on thymocytes from adult BALB/c mice were investigated following in vitro stimulation with the T cell mitogen Concanavalin A (Con A). Con A treatment resulted in a decrease in the relative percent of L3T4+/Ly2+ cells (double positive; immature) with a concomitant increase in the percent of Ly2 cells (suppressor/cytotoxic). No change in the percent of L3T4 cells (helper) occurred. In addition, Con A stimulation resulted in an increase in the absolute number of Ly2 cells, with no change in number of L3T4 cells. Stimulation with the mitogen led to an increase in fluorescence intensity (indicative of relative number of markers) of Ly2 markers on Ly2 single positive cells as well as on L3T4+/Ly2+ cells. There was a moderate mitogen induced increase of L3T4 markers, but only on L3T4 single positive cells. Exposure to THC resulted in a definitive suppressive effect on Con A induced thymus cell proliferation. The suppression was primarily evidenced in the single positive Ly2 subpopulations. Since the thymus is the source of immunocompetent lymphocytes to the secondary lymphoid organs, it seems plausible that marijuana negatively affects maturation of these cells in the developing individual.

Animals↗
PubMed1992

The RBE-LET relationship for rodent intestinal crypt cell survival, testes weight loss, and multicellular spheroid cell survival after heavy-ion irradiation.

This report presents data for survival of mouse intestinal crypt cells, mouse testes weight loss as an indicator of survival of spermatogonial stem cells, and survival of rat 9L spheroid cells after irradiation in the plateau region of unmodified particle beams ranging in mass from 4He to 139La. The LET values range from 1.6 to 953 keV/microns. These studies examine the RBE-LET relationship for two normal tissues and for an in vitro tissue model, multicellular spheroids. When the RBE values are plotted as a function of LET, the resulting curve is characterized by a region in which RBE increases with LET, a peak RBE at an LET value of 100 keV/microns, and a region of decreasing RBE at LETs greater than 100 keV/microns. Inactivation cross sections (sigma) for these three biological systems have been calculated from the exponential terminal slope of the dose-response relationship for each ion. For this determination the dose is expressed as particle fluence and the parameter sigma indicates effect per particle. A plot of sigma versus LET shows that the curve for testes weight loss is shifted to the left, indicating greater radiosensitivity at lower LETs than for crypt cell and spheroid cell survival. The curves for cross section versus LET for all three model systems show similar characteristics with a relatively linear portion below 100 keV/microns and a region of lessened slope in the LET range above 100 keV/microns for testes and spheroids. The data indicate that the effectiveness per particle increases as a function of LET and, to a limited extent, Z, at LET values greater than 100 keV/microns. Previously published results for spread Bragg peaks are also summarized, and they suggest that RBE is dependent on both the LET and the Z of the particle.

Animals↗
PubMed1992

Influences of witnessed affect on information processing in children.

Children between the ages of 5 and 10 years watched a videotape of a child having a routine medical exam. Embedded within the scenes were systematic variations of depicted facial affect shown by doctor and child. Measures were taken of autonomic reactions and information-processing errors in response to positive, neutral, and negative affective cues. For 5-6-year-olds, processing errors were greatest in the negative affect condition. Additionally, peak increases in heart rate (HR) and skin conductance level (SCL) were demonstrated by 5-6-year-olds in response to negative affect shown by the witnessed child; increases in HR were in turn predictive of processing errors. Older children (9-10 years) showed trends reflecting reduced processing errors in response to witnessed negative affect. It was suggested that younger children respond to salient threat cues with a "defensive" response pattern that is relatively adaptive at younger but not older ages.

Affect↗
PubMed1992

Retroperitoneal hematoma after blunt trauma.

We reviewed retrospectively 233 consecutive patients with retroperitoneal hematoma (RPH) resulting from blunt trauma. This study group represented 2.9 per cent of all admissions for blunt trauma and 13 per cent of all admissions for blunt abdominal trauma. Motor vehicle accidents predominated as the cause of injury. Fifty-five per cent of the patients had fractures of the pelvis. Laparotomy was the primary method used in diagnosing RPH (73 per cent). The RPH was located in zone I in 14 per cent of patients, zone II in 37 per cent, zone III in 46 per cent and zone IV in 3 per cent. The RPH was explored in 35 per cent of all patients. Major vessels were the most common organ system injured (21 per cent) in patients with zone I RPH. The kidney was the most commonly injured organ (27 per cent) in patients with zone II RPH. Injury of either the pancreas or duodenum in 14 per cent of patients with right-sided zone II RPH indicates the need for careful evaluation of those organs at operation. Patients with zone III RPH associated with fractures of the pelvis should be explored only rarely--when main iliac vascular injury is suspected (4.6 per cent in this series). Otherwise, a systematic approach using external fixator devices and angiographic embolization should be used. The over-all morbidity and mortality rates of 59 and 39 per cent, respectively, emphasize the need for aggressive resuscitation, rapid control of hemorrhage and a multidisciplinary approach to the management of these patients.

Abdominal Injuries↗
PubMed1992

Injuries of the abdominal aorta from blunt trauma.

Blunt injuries of the abdominal aorta are rarely reported in the literature. If left undiagnosed, these injuries may have catastrophic consequences. Four patients with blunt abdominal aortic lesions, identified in the authors' trauma registry, are presented in this report, along with a discussion of the pertinent literature to illustrate clinical management techniques. The mechanisms of injury include motor vehicular crashes (most frequent) with or without seatbelt use, abdominal blows, falls, and abdominal crush injuries. The spectrum of aortic lesions ranges from simple contusion or intramural hematoma to intimal disruption, false aneurysm, or frank rupture. Aortography should be performed in all stable patients with suspected aortic injury. All central-medial retroperitoneal hematomas discovered at laparotomy for blunt trauma should be explored after proximal and distal control of the aorta is obtained. Strict adherence to these principles, maintenance of standard vascular technique, and aggressive, expeditious resuscitative evaluation may improve survival.

Adult↗
PubMed1992

Priorities and diagnostic studies in the management of the injured patient.

The traumatized patient is best served by an orderly and sequential resuscitation and evaluation. Primary priorities include the establishment of a secure airway, adequate ventilation and hemodynamic status. These considerations should be followed by a brief history, systemic physical examination and radiographic studies. Studies utilized in blunt trauma include diagnostic peritoneal lavage and computed tomography. Nuclear magnetic resonance and ultrasound may prove useful in the future. In penetrating trauma, traversing missiles mandate surgical exploration. Stab wounds may be managed by several alternative methods. Emergency thoracotomy has a limited role in the blunt trauma patient but may be life saving in those suffering penetrating trauma.

Emergency Medical Services↗
PubMed1992

Pre-existing disease in trauma patients: a predictor of fate independent of age and injury severity score.

Improvement in trauma management requires a better understanding of the effect of a patient's preinjury health status on outcome. Specific historical findings and laboratory criteria were used to define pre-existing disease (PED) states and determine if they were independent predictors of fate in trauma victims. Of 7,798 adult patients admitted to a level I trauma center from July 1986 through June 1990, 16.0% (1,246) had greater than or equal to 1 PED. The PED+ and PED- patients had no significant difference in Injury Severity Scores (ISSs) (15.7 versus 15.6) and admission Glasgow Coma Scale (GCS) scores (13.9 versus 13.8). The PED+ patients were older (49.2 versus 30.6 years) (p less than 0.001) and had a higher mortality rate (9.2% versus 3.2%) (p less than 0.001) than PED- patients. Mortality rates were also elevated for patients with greater than or equal to 2 PEDs (18%) and for those with renal disease (38%), malignancy (20%), and cardiac disease (18%) (p less than 0.001) compared with PED- patients. Controlling for age and ISS, there was an association between PED and mortality (Mantel-Haenszel p less than 0.03). Multivariate regression showed that PED is an independent predictor of mortality (R2 = 0.1918; p less than 0.0001). The greatest increases in mortality were found among patients less than 55 years and with ISS less than 20. Changes in prehospital triage criteria and outcome scoring are needed. Improvements in the management of trauma victims with chronic disease may decrease their mortality rate.

Adult↗
PubMed1991

cAMP stimulates cholesteryl ester clearance to high density lipoproteins in J7774 macrophages.

The regulation by cAMP of cholesteryl ester hydrolysis and net depletion of cellular cholesteryl ester (cholesteryl ester clearance) in J774 murine macrophages was explored. Using Sandoz 58035 to selectively inhibit acyl CoA:cholesterol acyltransferase, we showed that the absolute rate of cholesteryl ester hydrolysis was stimulated 2-fold in J774 cells by the cAMP analogues 8-(4-chlorophenylthio)adenosine 3':5'-cyclic monophosphate and dibutyryl-cAMP. The rate of hydrolysis was also stimulated by prostaglandin E1, by cholera toxin, and by a mixture of forskolin and isobutylmethylxanthine, but was not affected by epinephrine or dibutyryl-cGMP. These data demonstrate that cholesteryl ester hydrolysis in J774 cells can be stimulated by cAMP-dependent protein kinase. Cholesteryl ester clearance from J774 cells was achieved upon incubation with high density lipoproteins (HDL) plus CPT-cAMP but not with HDL alone. HDL-mediated cholesteryl ester clearance was dependent on the concentration of both HDL and CPT-cAMP. The data suggest that the defect responsible for the lack of HDL-mediated cholesteryl ester clearance in J774 cells involves a failure to modulate cAMP levels.

Animals↗
PubMed1991

New horizons in management of hypothermia and frostbite injury.

Diagnosing hypothermia requires a high index of suspicion. Restoring lost heat with careful attention to hemodynamics usually results in complete recovery. Frostbite is best treated by physicians who are cognizant of the pathophysiology of cold injury. Although alternative methods of intervention are being tested, rapid rewarming and anti-inflammatory agents are integral to treatment protocols.

Accidents↗
PubMed1991

Congenital absence of the nose and nasal fossae.

We describe a case of complete nasal agenesis and absence of the nasal fossae, without alterations in the central nervous system. The physical and intellectual development of the infant to date has been absolutely normal. Opening of the nasal respiratory passage was not required in our patient as he did not show respiratory problems during deglutition. - Microphthalmia in the right eye with iridoretinal coloboma and right cryptorchidism were also noted. When the child was 9 months old a right orbital asymmetry became evident due to a growth deficit of the microphthalmic eye. This improved after placement of an expandable prosthesis in the orbit to stimulate its growth. - When the child is 4 years old, he will start to use a nasal prosthesis supported by implantology. Final reconstruction of the nasal pyramid will take place after he is 15 years of age.

Child, Preschool↗
PubMed1991

The role of cyclic nucleotide mediators in latency and reactivation of HSV-1 infected neuroblastoma cells.

The mechanisms that control herpes simplex virus type 1 latency and reactivation are still poorly understood. We developed an in vitro murine neuroblastoma cell HSV-infected, acyclovir suppressed model to study the influence of different cyclic nucleotide mediators on the latency and reactivation of HSV-1. A positive cDNA 'in situ' hybridisation for HSV genome was used to prove the establishment of a viral-host cell nuclear relationship. An ABC-immunoperoxidase reaction to cell surface HSV mature glycoproteins was also performed to determine the time of viral reactivation with formation of mature virions. Supernates of cultured cells were placed on Vero cells for confirmation of reactivation by classic cytopathic effect. Theophylline (50 micrograms/ml) and dibutyryl-cAMP (0.1, 0.5, 1 mg/ml) produced the most pronounced response, accelerating HSV reactivation time by 150%. Epinephrine (10, 20 micrograms/ml) had an intermediate effect on accelerating viral reactivation; and verapamil (20, 50 micrograms/ml), theophylline and epinephrine at lower doses had a smaller effect. Carbamylcholine (10 micrograms/ml) prolonged the time to viral reactivation by 100%, 36 hours compared to control time of 18 hours. Insulin (0.1, 0.5, 1 mg/ml) also prolonged HSV 'latency' by six hours. Exogenous dibutyryl-cGMP and carbamylcholine at lower concentrations did not have an effect on viral reactivation. These findings suggest that there is a relationship between changes of intracellular concentration of cyclic nucleotides and HSV latency and reactivation.

Animals↗