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Biomedical subjects

I Lopez

Publications and source records attributed to I Lopez.

At least 73 records · Page 4Linked to original sources
PubMed1995

Distribution of efferent cholinergic terminals and alpha-bungarotoxin binding to putative nicotinic acetylcholine receptors in the human vestibular end-organs.

Although acetylcholine (ACh) has been identified as the primary neurotransmitter of the efferent vestibular system in most animals studied, no direct evidence exists that ACh is the efferent neurotransmitter of the human vestibular system. Choline acetyltransferase immunohistochemistry (ChATi), acetylcholinesterase (AChE) histochemistry, and alpha-bungarotoxin binding were used in human vestibular end-organs to address this question. ChATi and AChE activity was found in numerous bouton-type terminals contacting the basal area of type II vestibular hair cells and the afferent chalices surrounding type I hair cells; alpha-bungarotoxin binding suggested the presence of nicotinic acetylcholine receptors on type II vestibular hair cells and on the afferent chalices surrounding type I hair cells. This study provides evidence that the human efferent vestibular axons and terminals are cholinergic and that the receptors receiving this innervation may be nicotinic.

Acetylcholinesterase↗
PubMed1994

Choline acetyltransferase immunoreactivity in the human vestibular end-organs.

Acetylcholine (ACh) is believed to play a major role in the efferent vestibular system in several animal models, however no information regarding the role of ACh in the human efferent vestibular system has been published. Post-embedding immunohistochemistry in a hydrophilic resin was used to investigate the choline acetyltransferase immunoreactivity (ChATi) and acetylcholinesterase (AChE) histochemistry in human vestibular end-organs. ChATi and AChE activity was found in numerous bouton-type terminals at the basal area of the vestibular hair cells. These terminals were found to contact type II vestibular hair cells and the afferent chalices surrounding type I hair cells. This study provides the first evidence that the human efferent vestibular axons and terminals are cholinergic.

Acetylcholinesterase↗
PubMed1994

Subcellular innervation patterns of the calcitonin gene-related peptidergic efferent terminals in the chinchilla vestibular periphery.

We examined the ultrastructural distribution of calcitonin gene-related peptide immunoreactivity in the peripheral vestibular system of the chinchilla to study the innervation patterns of this efferent neuropeptide. Immunoelectron microscopic localization of calcitonin gene-related peptide immunoreactive terminals in the maculae and cristae revealed an extensive innervation pattern on the afferent vestibular pathway. Calcitonin gene-related peptide immuno-reactive terminals made synaptic contacts with the unmyelinated portions of the primary afferent vestibular dendrites innervating both type I and type II hair cells. Abundant synaptic contact between calcitonin gene-related peptide immunoreactive terminals and the chalices surrounding type I hair cells was observed. Direct contact between calcitonin gene-related peptide immunoreactive terminals and type II hair cells was observed. In addition, vesiculated efferent terminals without calcitonin gene-related peptide immunoreactivity were seen synapsing on the chalices of type II hair cells and on the surrounding type I hair cells. The primary afferent somata in the vestibular ganglion of Scarpa did not contain calcitonin gene-related peptide immunoreactivity. Unmyelinated calcitonin gene-related peptide immunoreactive axons passed among the primary afferent fibers in Scarpa's ganglion, and these fibers continued through the subepithelial regions of the vestibular end-organs. The calcitonin gene-related peptide immunoreactive axons ramified to produce numerous calcitonin gene-related peptide immunoreactive terminals throughout the neurosensory epithelium of the maculae and cristae. These data suggest that calcitonin gene-related peptide-mediated modulation of the afferent vestibular system is functionally important.

Animals↗
PubMed1994

[Treatment of mucositis with vitamin E during administration of neutropenic antineoplastic agents].

Mucositis represents one of the most frequent complications during chemotherapy or radiotherapy. Few studies have showed effective prevention against mucositis in this setting. In this randomized study, we tested the efficacy of vitamin E in the treatment of chemotherapy-induced mucositis. Twenty patients with malignant haemopathies were included; 19 patients were evaluable for the prevention of mucositis. Ten patients were treated with induction therapy for acute myelogenous leukaemia and 9 were treated with intensive therapy followed by autologous bone marrow transplantations. The severity of mucositis was evaluated according to World Health Organization classification. Our results showed that vitamin E may be of therapeutical value in the prevention of mucositis especially during induction therapy for acute myelogenous leukaemia.

Adolescent↗
PubMed1993

Types of optometric testing emphasized in different practice modes.

BACKGROUND: In order to determine if tests performed in an examination vary with practice settings, we surveyed all 5,200 California licensed optometrists and asked them to identify their primary mode of practice and the percentage of time and/or frequency that certain test procedures were done in an eye examination. METHODS: We restricted our analysis to three practice modes: private, corporate, and nonprofit/health maintenance organization (NP/HMO). We received a 66.4 percent response rate. To determine any trends in emphasis of testing by the three practice modes and to establish relationships between the three, we compared each mode of practice to the other. The combinations were private vs. corporate, corporate vs. NP/HMO, and private vs. NP/HMO. The three combinations were compared to the frequency of performing case history, stereo acuity testing, binocular vision testing, biomicroscopy, dilated fundus examination, tonometry and perimetry. RESULTS AND CONCLUSIONS: We found the following relationships in the frequency/emphasis of testing as statistically significant: 1) For stereopsis testing: private practices performed it more often than corporate; 2) For binocular vision testing: private practices performed it more than did either corporate or NP/HMO, corporate performed it more than NP/HMO; 3) For tonometry: corporate performed it slightly more than NP/HMO; 4) For dilation: NP/HMO performed it more than both private and corporate; and 5) For perimetry: private performed it more than both corporate and NP/HMO.

Data Collection↗
PubMed1993

Influence of blood storage after in vitro exposure on the yield of micronuclei observed in human lymphocytes.

In a cooperative study, four laboratories evaluated the micronucleus test in irradiated and non-irradiated lymphocytes with respect to time of storage, the difference between X-ray and gamma exposure and inter-observer variance. The results were compared with parallel studies on dicentric aberrations. No significant differences between laboratories, with respect to storage time or between gamma and X-irradiation were observed for micronuclei and dicentrics using analysis of variance. However, micronuclei are not suitable for an assessment of exposure inhomogeneity because of a significant overdispersion already in controls and homogeneously irradiated samples.

Belgium↗
PubMed1991

Characterization of muscarinic receptors of bovine adrenal chromaffin cells: binding, secretion and anti-microtubule drug effects.

1. Binding of [3H]QNB to adrenal membranes is saturable, specific and to a single class of receptors. 2. Tubulozole, and not other microtubule drugs, inhibits [3H]QNB binding. 3. Pretreating cultured chromaffin cells with oxotremorine, a muscarinic receptor agonist, has no effect on either basal, nicotine (10 microM) or K(+)-stimulated catecholamine release and failed to enhance secretion of submaximal concentrations of nicotine (3-5 microM). 4. These results confirm that binding of [3H]QNB is associated with muscarinic receptors on bovine adrenal medullary tissue. 5. These studies also demonstrate that although bovine adrenal chromaffin cells possess muscarinic receptors, these receptors do not appear to be coupled to secretory processes.

Adrenal Glands↗
PubMed1991

[In vivo kinetics of cotrimoxazole in alveolar macrophages].

The aim of this work was to study the kinetic of intramacrophage penetration of cotrimoxazole in guinea pigs which had received 100 mg/kg of sulfamethoxazole and 20 mg/kg of trimethoprim after a single intraperitoneal injection. 30 minutes, 1, 3, 6 and 24 hours after this injection an intra-cardiac blood sample was taken and pulmonary lavage was performed immediately after sacrificing the animal by cervical cord dislocation. The level of trimethoprim and sulfamethoxazole was measured in each sample by high performance liquid chromatography (HPLC). An estimation of the dilution of the supernatant was obtained by comparing the supernatant glucose with the serum glucose. The serum kinetics of trimethoprim and sulfamethoxazole progressed in a parallel fasion with time with a maximal concentration at 30 minutes (for trimethoprim: 6.7 +/- 0.9 micrograms/ml and for sulfamethoxazole 176.1 +/- 16.2 micrograms/ml). On the other hand their penetration capacity was different in the supernatant and in the alveolar macrophages: the maximal concentrations were obtained after one hour in the supernatant and after 3 hours in the cellular extract and were respectively for trimethoprim 0.43 +/- 0.07 microgram/ml and 20.9 +/- 8.06 micrograms/ml of intramacrophage water and for sulfamethoxazole 1.86 +/- 0.24 micrograms/ml and 23.8 +/- 12.7 micrograms/ml of intramacrophage water. A concentration around six times greater was noted for the trimethoprim inside the cells compared with serum and was only 0.25 time for sulfamethoxazole. On the other hand the supernatant/serum ratio showed a greater concentration for trimethoprim (4 to 10) than for sulfamethoxazole (0.6 to 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The penetration of co-trimoxazole into alveolar macrophages and its effect on inflammatory and immunoregulatory functions.

The pharmacokinetics of co-trimoxazole in serum, bronchoalveolar lavage-fluid (BAL-fluid) and alveolar macrophages (AM) of guinea pigs receiving sulphamethoxazole (100 mg/kg) and trimethoprim (20 mg/kg) were studied. HPLC showed that peak co-trimoxazole levels were obtained in serum at 30 min, in BAL-fluid at 1 h and in AM at 3 h. A comparison between mean concentrations in serum, BAL-fluid and AM showed a six-fold higher concentration of trimethoprim in cells than in serum, but only 0.25-fold of sulphamethoxazole. The BAL-fluid/serum ratio was four to ten times higher for trimethoprim than for sulphamethoxazole (0.6-to-one-fold). Sulphamethoxazole/trimethoprim ratios (30 min, 1 and 3 h) were lower in BAL-fluid (4.9 +/- 0.5) and in AM (1.4 +/- 0.5) than in serum (30.7 +/- 1.6). The influence of co-trimoxazole in vitro on microbicidal capacities (superoxide anion and hydrogen peroxide generations), immunoregulation (production of interleukin 1) and pro-inflammatory agent production (tumour necrosis factor) of guinea pigs' AM was also studied. No significant effect of co-trimoxazole on superoxide anion and hydrogen peroxide generations, or on interleukin 1 and TNF production, was demonstrable.

Animals↗
PubMed1990

The effects of extracellular magnesium on myoplasmic [Ca2+] in malignant hyperthermia susceptible swine.

It is now well established that the pathophysiology of the malignant hyperthermia (MH) syndrome is related to a malfunction of intracellular calcium homeostasis. Magnesium plays important roles in the basic contractile properties of muscle, and many of its actions are antagonistic to those of calcium. The aim of this study was to determine the effectiveness of magnesium sulphate to prevent the MH episode in susceptible animals and correlate this with its effects on the intracellular free calcium [( Ca2+]i). The experiments were carried out using six control (Yorkshire) and ten MH-susceptible crossbred swine (Poland China X Pietrain). After determination of resting concentrations of [Ca2+]i and [Mg2+]i, each animal was given either two iv bolus doses of 50 mg/kg or one iv bolus of 100 mg/kg of MgSO4. The resting [Ca2+]i and [Mg2+]i were determined by means of ion-selective microelectrodes. The resting [Ca2+]i in normal muscle fibers was 0.11 +/- 0.01 microM (mean +/- SEM), whereas in the MH muscles the resting [Ca2+]i was 0.36 +/- 0.01 microM. In neither group was the resting [Ca2+]i modified by MgSO4. This cumulative dose of MgSO4 (100 mg/kg) was not able to prevent the induction of an MH episode by 2% halothane. Although MgSO4 did not directly decrease [Ca2+]i, it did attenuate the increase in [Ca2+]i associated with the syndrome from 7.29 +/- 0.43 microM in untreated animals to 0.84 +/- 0.03 microM in MgSO4 pretreated swine. In addition, the limb rigidity that accompanies this increase in calcium was prevented by MgSO4 pretreatment. Baseline measurements of [Mg2+]i were not different in control and MH-susceptible muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Study of the in vivo penetration of cotrimoxazole in alveolar macrophages].

Kinetic of cotrimoxazole was studied in serum, alveolar macrophages and BAL fluid from guinea pigs receiving sulfamethoxazole (SMX, 100 mg/kg) and trimethoprim (TMP, 20 mg/kg). Guinea pigs were killed by cervical dislocation 30 min, 1 h, 3 h, 6 h and 24 h after intraperitoneal injection. Lung lavage was performed to obtain alveolar macrophages and BAL fluid. TMP and SMX levels were assayed using high-performance-liquid chromatography. Highest SMX levels were obtained in serum at 30 min, in BAL fluid at 1 h and in alveolar macrophages at 3 h. Mean SMX/TMP ratios (30 min, 1 h, 3 h) was 26.5 +/- 0.8 in serum, 3.76 +/- 1.8 in BAL fluid and 1.15 +/- 0.02 in alveolar macrophages.

Animals↗
PubMed1989

[Neutralizing activity against herpes simplex in maternal milk].

Human milk could play a role in the protection of the newborn from Herpes simplex virus 2 contamination. Neutralizing activity against Herpes simplex virus 2 was measured in 94 human milk samples and in 31 sera from healthy women. A weak neutralizing activity was detected in 48 milk samples. They were neither correlated to anti-Herpes simplex virus antibodies found in milk, nor to the neutralizing activity in sera. The origin and non immunologic nature of this activity are discussed.

Antibodies, Viral↗
PubMed1988

Metabolism of nephrotoxic isopropylcyclohexane in male Fischer 344 rats.

The metabolism of isopropylcyclohexane and associated renal pathology were evaluated in male Fischer 344 rats exposed by oral gavage. The rats experienced moderate proximal tubular damage similar to that produced by acyclic, branched-chain hydrocarbons. The urinary metabolites of isopropylcyclohexane included cis-4-isopropylcyclohexanol, trans-4-isopropylcyclohexanol, 2-cyclohexylpropanoic acid, 2-cyclohexyl-1,3-propanediol, 2t-hydroxy-4t-isopropylcyclohexanol, 2c-hydroxy-4c-isopropyl-cyclohexanol, and 2c-hydroxy-4t-isopropylcyclohexanol. The extent and preferred sites of oxidative metabolism of nephrotoxic hydrocarbons could potentially prove useful in elucidating the pathogenic mechanisms.

Administration, Oral↗
PubMed1988

Pseudomelanosis of the duodenum. Endoscopic, histologic, and ultrastructural study of a case.

We present the endoscopic, microscopic, and histochemical studies of a patient with pseudomelanosis of the duodenum. The pigment was located mainly in the lysosomes of macrophages in the lamina propria and was heterogeneous, showing features of melanin, pseudomelanin, and hemosiderin. The origin of this pigment remains unknown, but antihypertensive medication may have played a role.

Aged↗
PubMed1987

The metabolism of t-butylcyclohexane in Fischer-344 male rats with hyaline droplet nephropathy.

The molecule t-butylcyclohexane is one of the first examples of a branched alkyl group attached to a hydrocarbon ring shown to be capable of producing renal damage at the corticomedullary junction of male rats. A metabolic study of t-butylcyclohexane yielded the following urinary metabolites: trans-4-t-butylcyclohexanol, 2c-hydroxy-4t-t-butylcyclohexanol, 2-methyl-2-cyclohexylpropanoic acid, 2c-hydroxy-4c-t-butylcyclohexanol, 2-methyl-2-cyclohexyl-1,3-propanediol, 2t-hydroxy-4t-t-butylcyclohexanol, and cis -4-t-butylcyclohexanol. As with other hydrocarbons of similar molecular weight that induce nephropathy in male rats, preferential sites of oxidative metabolism were observed that could potentially be related to the pathogenesis.

Animals↗
PubMed1987

Fast imaging of CSF flow/motion patterns using steady-state free precession (SSFP).

Using a rapid Fourier SSFP imaging technique, which is sensitive to slow flow (approximately 1 mm/sec) in the plane of the image, we obtained 135 brain MRI examinations. The CSF flow/motion patterns were mapped by two images with orthogonal in plane flow sensitivity directions. Analysis showed significant deviations from the "normal" pattern in ventricular enlargements because of obstruction (no evidence of CSF flow/motion) or in normal pressure hydrocephalus (complex, intensive flow pattern in lateral ventricles) suggesting a diagnostic potential for this fast imaging technique.

Brain↗
PubMed1987

Nodular regenerative hyperplasia of the liver in renal transplantation.

In our series of RT three cases of diffuse NRH of the liver were found. This rare entity is characterized by nodules of regenerative hepatocytes distributed throughout the liver without fibrosis. The incidence was 12.5% and probably is underestimated. Clinically, hepatomegaly, moderate thrombopenia and an elevation of GGT were present, but no case was previously suspected. NRH can lead to PH, and we should think of this entity in the differential diagnosis of PH following RT.

Adult↗