Biomedical subjects

A R Gonzalez

Publications and source records attributed to A R Gonzalez.

16 recordsLinked to original sources

PubMed2005

Natural occurrence of hexavalent chromium in the Aromas Red Sands Aquifer, California.

To address increasing concerns of chromium contamination in the drinking water of Santa Cruz County, we designed a study to investigate the source(s) and spatial gradients of the chromium concentration and speciation in local aquifers. This study was catalyzed by a report (January 2001) bythe Soquel Creek Water District of elevated hexavalent chromium concentrations ranging from 6 to 36 microg L(-1), approaching the state's maximum concentration limit of 50 microg L(-1), in the Aromas Red Sands aquifer. To test the accuracy of those preliminary measurements, we collected groundwater using trace metal clean techniques from 11 sites in Santa Cruz County, including 10 from the aquifer with reportedly elevated chromium concentrations and 1 from an adjacent aquifer, the Purisima, and analyzed them fortotal chromium using inductively couple plasma mass spectrometry. Nine of the reportedly 10 contaminated sites had total chromium concentrations ranging from 5 to 39 microg L(-1), while one from the control site was below the limit of detection (0.01 microg L(-1)). We also measured the speciation of chromium at all sites using a solid supported membrane extraction coupled with graphite furnace atomic absorption spectrometry and determined that on average 84% of total chromium was Cr(VI). In addition to the groundwater analyses, a series of extractions were performed on sediment samples from both the Aromas Red Sands and Purisima aquifers. These tests were used to empirically characterize sediment trace metal (Cr, Fe, Mn) distributions in five phases providing information about the origin, availability, reactivity, and mobilization of these trace metals. Results from groundwater and sediment samples indicate that the chromium is naturally occurring in the Aromas Red Sands aquifer, possibly by Cr(III) mineral deposits being oxidized to Cr(VI) by manganese oxides in the aquifer.

California↗

PubMed1995

Fryns syndrome: neurologic findings in a survivor.

Fryns syndrome, a multiple congenital anomaly syndrome associated with diaphragmatic defects, craniofacial dysmorphism, distal digital hypoplasia, and neurologic abnormalities, was first described in 1979. This autosomal recessive disorder is usually associated with stillbirth or death immediately after birth. Detailed neurologic findings in the third survivor beyond the neonatal period are reported, and neurologic abnormalities in other cases are reviewed. Initially, hypotonia, areflexia, and weakness were seen. Myoclonus developed immediately after birth and was well controlled with high-dose valproate. Electroencephalography revealed slowing and irregular paroxysmal discharges with spikes and sharp waves that disappeared with time and treatment. Magnetic resonance imaging demonstrated partial agenesis of the corpus callosum, a Dandy-Walker malformation, and progressive cerebral and brainstem atrophy. This syndrome should be considered in patients with unusual facial features and digital abnormalities associated with frequent early myoclonus.

Abnormalities, Multiple↗

PubMed1993

Changes in subcellular accumulation of contractile proteins in myocardiocyte cultures: effects of fibric acid derivatives.

We analyzed the influence of 6 and 24 h of treatment with the fibric acid derivatives bezafibrate (10 micrograms/ml), gemfibrozil (23 micrograms/ml), and fenofibrate (30 micrograms/ml) on alpha-actinin, troponin-T, and tropomyosin proteins in the cytoplasmic and cytoskeletal fractions of cultured chick myocardiocytes. The findings with sodium dodecyl sulfate-gel electrophoresis and immunoblotting showed that all three drugs modified cellular and subcellular protein levels in different ways: bezafibrate and fenofibrate produced the most significant alterations in both fractions, modifying alpha-actinin, troponin T, and tropomyosin compartmentalization in myocardiocytes, whereas gemfibrozil altered these proteins less notably. Given the role of these proteins in heart muscle contraction, fibric acid derivative-induced changes may be related with the secondary effects of these drugs on heart rhythmicity.

Actinin↗

PubMed1993

Effects of estrogen-progestin replacement therapy on plasma beta-endorphin levels in menopausal women.

Serum beta-endorphin, LH, FSH, estradiol (E2) and progesterone (P) were measured in postmenopausal women before and after four different estrogen-progestin replacement therapies. Our result showed that serum E2 increased significantly and serum LH and FSH decreased significantly after all treatments. Serum P levels were similar before and after all treatments. Serum beta-endorphin levels increased significantly after cyclic administration of estrogen-progestin, but not after continuous administration of E2. We conclude that the frequently observed beneficial effects of estrogen-progestin replacement therapy on behavior and mood in postmenopausal women may be related to changes in peripheral opioid levels.

Estrogen Replacement Therapy↗

PubMed1989

Protection of mice from herpes simplex virus-induced retinitis by in vitro-activated immune cells.

A form of acute retinal necrosis occurred in the contralateral eyes of susceptible mice 1 week after each received a uniocular injection of live herpes simplex virus type 1 (HSV-1) in the anterior chamber. Although these mice did not develop systemic delayed hypersensitivity to virus antigens, their sera contained virus-specific antibodies at the time contralateral retinitis occurred. These findings suggest that systemic immunity might not be able to protect against contralateral retinitis. To explore this possibility further, we examined lymph nodes and spleens of intraocularly infected mice to determine whether their lymphoid tissues contained primed HSV-1-specific cytotoxic T cells. Virus-specific cytotoxic T cells were readily identified in these mice. We wondered why successful immune priming did not confer protection against HSV-1 retinitis. We examined this issue by evaluating the capacity of in vitro-generated, HSV-1-specific effector T cells to prevent retinitis by infusing these cells by various routes and at various times into mice that received an intracameral injection of HSV-1. The results revealed that virus-specific effector cells could prevent contralateral retinitis if injected intravenously or into the anterior chamber of the contralateral eye at the same time that virus was injected into one eye. However, the effector cells failed to prevent retinitis if they were injected into the same eye that received HSV-1 or if their intravenous administration was delayed until 24 h after the HSV-1 injection into the eye. We concluded that immune T cells can protect against contralateral retinal necrosis caused by uniocular injection of HSV-1 into the anterior chamber but only if they are administered during the first 24 h after virus infection. We propose that a retinitis-inducing process is set in motion during this early time interval postinfection. Once the process has been initiated and established, it is no longer susceptible to immune intervention. It would appear that mice that are susceptible to contralateral retinitis fail to mobilize a protective response quickly enough to ward off the establishment of the retinitis-inducing process and its disastrous eventuality.

Animals↗

PubMed1987

Pulmonary edema in severe preeclampsia-eclampsia: analysis of thirty-seven consecutive cases.

During approximately a 9-year period, 37 severe preeclamptic-eclamptic patients had pulmonary edema for an incidence of 2.9%. The incidence was significantly higher in older patients (p less than 0.0001) and in multigravid patients (p less than 0.05). Eleven (30%) had antepartum edema with 10 (90%) of the 11 having preexisting chronic hypertension. Twenty-six (70%) had postpartum edema with an average onset of 71 hours post partum. The majority of these patients had excessive colloid and crystalloid infusions for various medical, surgical, and obstetric complications. There were four maternal deaths and morbidity was significant. Eighteen patients had disseminated intravascular coagulopathy, 17 had sepsis, 12 had abruptio placentae, 10 had acute renal failure, six had hypertensive crisis, five had cardiopulmonary arrest, two had rupture of the liver, and two had ischemic cerebral damage. The overall perinatal mortality was 530/1000 and neonatal morbidity was significant. Pulmonary edema is infrequent in severe preeclampsia-eclampsia without associated medical, surgical and obstetric complications. The occurrence of pulmonary edema in such patients is associated with high maternal and perinatal mortality and morbidity.

Adult↗

PubMed1987

A comparative trial of labetalol and hydralazine in the acute management of severe hypertension complicating pregnancy.

Sixty peripartum patients with diastolic blood pressures (BP) 110 mmHg or higher were randomized in a 2:1 ratio to receive repeated intravenous injections of either labetalol (20-80 mg) or hydralazine (5 mg) until the diastolic BP was below 100 mmHg. There were four treatment failures in the labetalol group (N = 40) and none in the hydralazine group (N = 20). Hydralazine lowered mean arterial pressure (MAP) more than did labetalol (33.3 +/- 13.2 versus 25.5 +/- 11.2 mmHg; mean +/- SD), but labetalol had a more rapid effect. There was considerable interpatient variability in the dose of labetalol required to control BP, which could not be predicted by any clinical characteristic before therapy. The duration of action also varied in the labetalol group, with the shortest duration occurring in those patients who required the highest dosage for BP control. No significant fetal or neonatal problems ascribable to drug treatment were noted in the 13 instances in which labetalol was given before delivery. However, fetal distress occurred in two of the six cases involving antenatal hydralazine. We conclude that labetalol appears to be a safe and effective alternative to hydralazine for treating hypertension in the peripartum period, but serious rare side effects have not yet been quantified.

Adult↗

PubMed1987

A comparison of labetalol plus hospitalization versus hospitalization alone in the management of preeclampsia remote from term.

Two hundred primigravid women with mild preeclampsia at 26-35 weeks' gestation were randomly allocated to treatment with hospitalization alone or combined with labetalol. There were no differences between the two groups in mean systolic or diastolic pressures, mean gestational age, or initial laboratory findings at time of entry. Patients in the labetalol group demonstrated a statistically significant (P less than .005) decrease in blood pressure during treatment. No such decrease occurred in the hospitalization-alone group. Both groups exhibited significant deterioration in proteinuria, creatinine, and uric acid. The average days of pregnancy prolongation (mean +/- SD) were 21.3 +/- 13 and 20.1 +/- 14 days in the hospitalization and labetalol groups, respectively. There were no differences between the groups regarding any of the following: gestational age at delivery, birth weight, number of infants admitted to the special care unit, or cord blood gas measurements. However, the incidence of small-for-gestational-age infants was significantly higher in the labetalol group (19 versus 9%, P less than .05). There were no stillbirths, but one neonatal death in the labetalol group. Treatment of maternal blood pressure in preeclamptic pregnancies with labetalol did not improve perinatal outcome, and was associated with a higher frequency of fetal growth retardation.

Adult↗

PubMed1978