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Biomedical subjects

A Carranza

Publications and source records attributed to A Carranza.

At least 19 recordsLinked to original sources
PubMed2005

Low sodium intake induces an increase in renal monoamine oxidase activity in the rat. Involvement of an angiotensin II dependent mechanism.

AIMS: The interplay between natriuretic dopamine and antinatriuretic angiotensin II represents an important mechanism for the regulation of renal sodium and water excretion. Monoamine oxidase is the main metabolizing pathway for dopamine in the renal cortex. In this study, we have analysed the effect of low sodium feeding and AT1 receptor blockade on renal dopamine metabolism by monoamine oxidase. METHODS: Four groups of rats were studied: 1, normal salt diet (NS); 2, low salt diet (LS); 3, NS receiving Losartan (Los, specific AT1 receptor antagonist, 20 mg kg(-1) bwt day(-1), NS + Los); 4, LS receiving Los (LS + Los). RESULTS: Urinary dopamine excretion was lower in LS than in NS rats (543 +/- 32 vs. 680 +/- 34 ng day(-1) 100 g(-1) bwt, P < 0.05). When treated with Los, DOPAC excretion and urinary DOPAC/dopamine ratio fell significantly in the LS + Los group as compared with the LS group (1199 +/- 328 vs. 3081 +/- 681 ng day(-1) 100 g(-1) bwt and 1.90 +/- 0.5 vs. 5.7 +/- 1.2, respectively, both P < 0.02). Losartan increased hydroelectrolyte excretion in the LS group. No changes were found in the NS + Los group. Aromatic L-amino acid decarboxylase activity in cortex was similar in NS and LS rats. Instead, monoamine oxidase activity was higher in cortical homogenates from LS rats (in nmol mg tissue(-1) h(-1): NS 7.66 +/- 0.52; LS 9.82 +/- 0.59, P < 0.05) and this difference was abolished in LS + Los rats (7.34 +/- 0.49 nmol mg tissue(-1) h(-1), P < 0.01, vs. LS). CONCLUSIONS: We have concluded that low levels of dopamine in the urine of LS rats are because of an increase in the activity of renal monoamine oxidase and that angiotensin II mediates this increase through stimulation of AT1 receptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2003

[Helicobacter pylori in children in Hospital Nacional de Niños, San José de Costa Rica].

Infection with Helicobacter pylori is more prevalent in developing than in developed countries. Several publications from Costa Rica associate this agent with almost 70% of the adults suffering gastritis; however, there are not data about its prevalence in children. In order to address that gap in the epidemiology of Helicobacter pylori in Costa Rica, we study 264 children (3 months to 17 years old) remitted to upper endoscopy due to dyspeptic disorders. From each case at least two biopsies were taken; one for Helicobacter isolation and the others for histopathological study. 96 of the children showed any grade of gastritis and in 73 of them was identified H. pylori; also, this agent was associated with 11 of the children without alteration in their gastric mucosa. In total, H. pylori was identified in the 31.8% of the studied cases. The two younger patients infected were a 1 and 2 years-old boys; the former had normal mucosa and the other had gastritis. These data confirm the importance of investigate Helicobacter in young children with gastric discomfort, mainly in developing countries.

Adolescent↗
PubMed2001

Selective inner hair cell loss in premature infants and cochlea pathological patterns from neonatal intensive care unit autopsies.

BACKGROUND: Deafness and handicapping sensorineural hearing impairment occur frequently in neonatal intensive care unit survivors for unknown reasons. PATIENTS AND METHODS: Hearing was tested early and repeatedly in neonatal intensive care unit patients with an auditory brainstem response (ABR) screener. The temporal bones of 15 nonsurvivors (30 ears) were fixed promptly (average, 5 hours) after death for histological evaluation. RESULTS: Among these patients, 12 failed the ABR screen bilaterally, 1 passed unilaterally, and 2 passed bilaterally. Cochlear histopathologic conditions that could contribute to hearing loss included bilateral selective outer hair cell loss in 2 patients, bilateral selective inner hair cell loss in 3 (all premature), and a combination of both outer and inner hair cell loss in 2. Other hair cell abnormalities were noted; the 2 infants who had passed the ABR screen demonstrated normal histological features. Neuronal counts were normal. CONCLUSIONS: Auditory brainstem response failure among these neonatal intensive care unit infants who died was extremely common in part owing to an unexpected histological alteration, selective inner hair cell loss among premature newborns, that should be detectable uniquely by the ABR testing method. Additional histological patterns suggest more than one cause for neonatal intensive care unit hearing loss. Hair cell loss patterns seem frequently compatible with in utero damage.

Cochlea↗
PubMed2001

In vitro interaction of bacteria with polypropylene/ePTFE prostheses.

The infection of an implanted prosthetic material can have serious consequences on the tissue integration of the implant and the scarring process in the host, and may even necessitate replacement of the prosthesis. This study was designed to explore the in vitro effects of Staphylococcus aureus (Sa) and Staphylococcus epidermidis (Se) on polypropylene (PL) and expanded polytetrafluoroethylene (ePTFE) prostheses. Fragments of PL and ePTFE were placed in a medium previously inoculated with Sa, Se or Sa + Se (1 x 10(8) cfu Sa or/and Se). Bacterial effects on the biomaterials were evaluated for 30 days through scanning electron microscopy (SEM). In order to confirm the presence of bacteria on the prostheses, specimens were Gram stained and challenged with an antibody against protein-A (a specific Sa bacterial wall component). In both methods, specimens were examined by light microscopy. The presence of bacteria as microcolonies or biofilms was detected at PL filament cross-over regions after 30 days. Bacterial colonization of the ePTFE fragments was observed in internodal areas, which led to the deformation of prosthetic filaments. The present findings indicate that Sa and Se colonize the cross-over regions of the PL filaments, whereas in ePTFE prostheses, it is the internodal areas which are mostly affected. The latter areas are of difficult access to defence agents.

Biocompatible Materials↗
PubMed2001

Decreased tubular uptake of L-3,4-dihydroxyphenylalanine in streptozotocin-induced diabetic rats.

BACKGROUND/AIMS: This study determined alterations in renal dopamine production in streptozotocin-treated rats and explored the mechanisms underlying this alteration. METHODS: Streptozotocin (65 mg/kg) or vehicle was administered to 3-month-old male Wistar rats. Treated animals had hyperglycemia, glycosuria and increased diuresis, natriuresis and excretion of L-dopa. Urinary dopamine and dihydroxyphenylacetic acid were similar to those in control animals. The production of dopamine by renal cortex slices from treated rats was significantly less than that from control animals. The addition of glucose (8.4-18.4 mM) to the incubation medium decreased about 40% the uptake of L-dopa by isolated proximal tubular cells. Scatchard analysis of the saturation curves obtained in this condition showed a decrease in the V(max) without changes in the K(m). RESULTS: Our results confirm previous studies suggesting a renal dopaminergic deficiency in insulin-dependent diabetes and provide evidence strongly suggesting that a decrease in the number of tubular L-dopa transport sites is the underlying defect of this deficiency. CONCLUSION: These results highlight the role of the uptake of dopa as an important modulator of renal dopamine synthesis.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2001

Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress.

Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.

Adrenal Cortex Hormones↗
PubMed2000

L-Dopa uptake and dopamine production in proximal tubular cells are regulated by beta(2)-adrenergic receptors.

This study assessed the role of adrenergic receptors on the regulation of the uptake of L-dopa and the production of dopamine by renal tubular cells. Scatchard analysis showed two L-dopa uptake sites with different affinities (K(m) 0.316 vs 1.53 microM). L-Dopa uptake was decreased by the nonselective adrenergic agonists epinephrine or norepinephrine (40%), by the beta-selective agonist isoproterenol or the beta(2)-selective agonist terbutaline (60%), but not by alpha-selective agonists (all 1 microM). The effect of norepinephrine, isoproterenol, or terbutaline was unaffected by addition of the beta(1)-antagonist atenolol, abolished by ICI-118, 551, a beta(2)-antagonist (both 0.1 microM), and mimicked by the addition of dibutyryl-cAMP (1 microM). Preincubation with terbutaline decreased the number of high-affinity uptake sites (V(max) = 1.10 +/- 0.3 vs. 0.5 +/- 0.1 pmol. mg protein(-1). min(-1)) without changing their affinity. Norepinephrine or terbutaline decreased dopamine production by isolated cells, and this effect was abolished by ICI-118,551 (0.1 microM). In vivo administration of ICI-118,551 reduced the urinary excretion of L-dopa and increased the excretion of 3,4-dihydroxyphenylacetic acid without significant changes in plasma L-dopa concentrations. These results demonstrate that stimulation of beta(2)-adrenergic receptors decreases the number of high-affinity L-dopa uptake sites in isolated tubular cells resulting in a reduction of the uptake of L-dopa and the production of dopamine and provide evidence for the presence of this mechanism in the intact animal.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Disseminated histoplasmosis in infants.

BACKGROUND: Disseminated histoplasmosis usually occurs in immunocompromised patients who reside in Histoplasma capsulatum-endemic regions. It has also been described in immunocompetent infants after exposure to a large inoculum of the pathogen resulting in case fatality rates of 40 to 50%. METHODS: From 1983 through 1996 all infants with documented disseminated histoplasmosis were treated with amphotericin B followed by daily ketoconazole for 3 months. Immunologic workups were performed at the time of diagnosis and at 4 to 6 weeks of therapy. Surviving patients were followed for at least 1 year. Time to resolution of signs and symptoms was recorded, as were complications. RESULTS: We managed 40 patients with disseminated histoplasmosis. The age in months at diagnosis was 15.3+/-10.2 (mean +/- SD), and 24 were male. All patients were from endemic regions and they presented with fever, spleen and/or liver enlargement and hematologic abnormalities. Diagnosis was made by histology and culture of bone marrow, spleen, lymph node, bronchoalveolar or liver samples. Twenty patients presented with T cell deficiency that resolved at 4 to 6 weeks of therapy in all of the retested patients, and 10 of 12 tested patients had hyperglobulinemia that resolved. Thirty-five (88%) patients were cured by treatment; 4 died and 1 relapsed. CONCLUSIONS: Disseminated histoplasmosis should be considered in infants from endemic areas who present with fever, hepatosplenomegaly and hematologic abnormalities. These patients develop transient hyperglobulinemia and T cell deficiency that resolve with treatment. Treatment with amphotericin B followed by an oral azole for 3 months is effective in most patients.

Amphotericin B↗
PubMed1998

Complete absence or deficiency of one half of the body.

Here we report on an apparently unprecedented case of virtually complete absence of the left half of the body, with resulting severe deformity of the right half. The fetus was stillborn with polyhydramnios at 31 1/2 weeks of gestational age. A second patient may be a mild example of this extraordinary phenomenon with deficiency of organs, predominantly on the left side. The nosology and developmental implications are discussed briefly.

Abnormalities, Severe Teratoid↗
PubMed1997

Intraotic administration of gentamicin: a new method to study ototoxicity in the crista ampullaris of the bullfrog.

A new method of local gentamicin administration was tested in the bullfrog inner ear to achieve ototoxic-induced hair cell destruction. Gelfoam pledgets soaked with known amounts of gentamicin were inserted into the perilymphatic cisterna of the bullfrog through a ventral surgical approach. A dose of 1.20 mg gentamicin, consistent with a perilymphatic concentration of 65 microg/ml, resulted in the desired ototoxic-induced hair cell damage, that is, complete hair cell destruction with minimal disruption of other components of the sensory epithelium. This study demonstrates that this is a useful and simple method to investigate the process of vestibular ototoxicity and hair cell regeneration, including aspects of hair cell destruction and repair.

Administration, Topical↗
PubMed1997

Suppression of the reactive hyperemic response in the forearm due to local hand cooling.

METHODS: Forearm blood flow (FBF) was measured by electrical impedance plethysmography in order to identify the influence of local cooling of the contralateral hand after 3 min of arterial occlusion. Ten volunteers (six females, four males) were randomly assigned to the following three experimental conditions on separate days: a) 6 min of local hand cooling (5-7 degrees C); b) 3 min of arterial occlusion of the forearm; and c) combined arterial occlusion and local cooling. RESULTS: All subjects experienced the typical pressor response during 6 min of hand cooling as evidenced by the significant increase (p < and = 0.05) in heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP). The FBF responses demonstrated an immediate increase (p < and = 0.05) within the first 30 s of hand submersion and then progressively declined over the next 5 min. The forearm vascular resistance (FVR = MAP/FBF) made an initial drop during the first 30 s of cooling and then gradually rose to reach peak levels between 5-6 min of cooling. With respect to the hyperemic response, FBF significantly increased (p < and = 0.05) from baseline (mean +/- SEM; 1.09 +/- 0.18 ml x 100 ml-1.min-1) and achieved peak levels (6.75 +/- 0.64 ml x 100 ml-1.min-1) within the initial 30 s of the post-occlusion period. Thereafter, FBF declined rapidly by 30-60 s (1.67 +/- 0.29 ml x 100 ml-1.min-1) and 60-90 s (1.26 +/- 0.33 ml x 100 ml-1.min-1) of the post-occlusion period. CONCLUSION: When the reactive hyperemic response was coupled with hand cooling, FBF increased above baseline values and reached peak levels during the initial 30 s of the post-occlusion period. However, the magnitude of the hyperemic response was significantly lower in the cold condition compared to the hyperemia alone (3.20 +/- 0.42 vs 6.75 +/- 0.64 ml x 100 ml-1.min-1; p < and = 0.05). Clearly, the overall sympathetic response to local cooling had an overriding effect on the factors that promote peripheral vasodilation following brief periods (3 min) of arterial occlusion.

Adult↗
PubMed1991

[Neuroblastoma in Costa Rica: the experience with 76 cases treated at the Hospital Nacional de Niños].

Between 1970 an 1988, 76 patients with neuroblastoma (39 males and 37 females) were treated at the National Children's Hospital. The children's ages ranged from 1 month to 10 years. The location of the neuroblastoma was retroperitoneal in 71% of the cases, mediastinal in 20%, in either the head or neck 4% and unknown in 5%. Twelve percent were classified as E I-II, 35% in E III, 50% in E IV and 3% in E IVS. Seventy-seven percent of the cases died and the remaining 33% are in remission, with a follow-up of 12 to 220 months. Fifty of the cases were histologically reclassified according to Shimada. Survival rates were correlated with age, histology, E classification and treatment, in order to establish prognostic factors in relation to the disease: children under 24 months have a survival rate of 43%, statistically greater than in those children older who have an 8% survival rate. Shimada's classification is useful in predicting the child's survival when under 18 months of age and with tumors with a low ICM (81% survival) and a high ICM (6%). Patients classified as E I-II have a survival rate of 74%, those in E III-38% and in E IV-4%. In relation to the chemotherapy, a ten year survival is thought to be 14% for the 22 cases in E III and IV who were given medication and 21% for the other 36 who were given three drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1989

[Thyroid nodules in children. Experience at the National Children Hospital of Costa Rica].

Clinical charts and biopsies of 32 children with thyroid nodules were reviewed at the National Children's Hospital from 1970 to 1988. The classification between benign and malignant types was only possible by surgery and biopsy. Twenty three (72%) were found to be benign forms and nine (28%) were carcinomas (8 papillary and one follicular). Two of the carcinomas had been irradiated previously because of neuroblastoma, as well as one of the benign type who received radiation to the neck and mediastinum because of a Hodgkin's disease. No patients showed alteration in thyroid functional test (T4 and TSH). Twenty two per cent of the carcinomas and 16% of the benign forms presented higher retention in the gammagram test. Seventy eight per cent of the carcinomas and 70% of the benign types showed a normal gammagram test. Surgery in the benign cases included 10 hemithyroidectomy, 7 sub-total thyroidectomy, 3 total thyroidectomy and 3 node resection. Carcinoma cases included 6 patients with total thyroidectomy with ganglionar modified dissection in three patients; 2 hemithyroidectomy and one with sub-total thyroidectomy. Complications included 3 hypoparathyroidisms, one of them permanent, 3 transitory recurrent paresis and only one child died because of pulmonary metastasis. All carcinoma patients were treated with levothyroxine and three of them also received 1131 in order to control ganglionar metastasis. Total survival rate for carcinoma patients was 83% at 90 months. It is concluded that only with surgery it is possible to classify correctly the histological type of children with thyroid nodes. Clinical evaluation and laboratory tests are useless. However, it has not been defined how big the surgery must be.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Treatment and outcome of undifferentiated carcinoma of the nasopharynx in childhood: a 13-year experience.

Between 1970 and 1983, 22 pediatric patients diagnosed as having undifferentiated nasopharyngeal carcinoma (UNC) were treated at the National Children's Hospital of Costa Rica; primary tumor with local extension (T3-T4) was present in 45% of the patients, and metastasis of the cervical nodes (N1-N3) in 82%. Patients were divided into groups A and B according to the type of treatment received. A description of both groups is as follows. Ten patients were treated with 5,000 to 6,000 rads tumor dose to the primary and a 5,125-rad dose was administered to the lower neck between 1970 and 1977 (group A). Six patients received postradiation therapy with cyclophosphamide and vincristine and two patients also received 5-fluorouracil. The outcome in group A was as follows: four (40%) failed to respond, six (60%) achieved full remission initially with two subsequent relapses, and the remaining four are still alive and free of relapse after 90 to 160 months (average 130) (two were treated with Co60 alone and two with chemotherapy. Twelve patients were treated with chemotherapy pre- and postradiation with CPM and adriamycin for a total of 12 months (group B) between 1978 and 1984. All (100%) achieved complete initial remission; two patients relapsed and died. Ten patients have remained in relapse-free survival for 18-67 months (median 32). Though this is not a controlled study, our experience indicates that pre- and postradiation chemotherapy is effective in prolonging the disease-free survival in UNC and may allow a decrease of the radiation tumor dose.

Adolescent↗