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Biomedical subjects

D Montoya

Publications and source records attributed to D Montoya.

At least 19 recordsLinked to original sources
PubMed2001

Age-related differences in neurosteroid potentiation of muscimol-stimulated 36Cl(-) flux following chronic ethanol treatment.

Alcoholism and alcohol abuse create costly social and economic problems in many nations. Recent studies indicate that alcohol exposure during adolescence may convey unique risks for subsequent neurocognitive deficits and problem drinking. Although GABA(A) receptor function is one of the principle neurochemical targets of ethanol action in the adult brain, little is known about the effects of alcohol on this system during adolescence. Adolescent (30-day-old) and adult (90-day-old) male rats were intermittently exposed to ethanol for 1 month. At various times after the end of the exposure period, synaptoneurosomes were prepared from their cerebral cortices. GABA(A) receptor-mediated 36Cl(-) influx was measured in the absence and presence of the neurosteroid 3alpha,21-dihydroxy-5alpha-pregnan-20-one (THDOC). In tissue from ethanol-exposed animals, sensitization to the potentiating effects of the neurosteroid was apparent 5 and 12 days after ethanol withdrawal. This sensitization was more apparent at the low concentrations of THDOC in animals pretreated with ethanol as adolescents. Sensitization to the potentiating effects of a neurosteroid is an enduring phenomenon, persistent long after the acute phase of ethanol withdrawal, and may be indicative of long-term changes in GABA(A) receptor function. Enhanced neurosteroid sensitization in animals pretreated as adolescents is consistent with the notion that adolescence is a period of unique sensitivity to the effects of ethanol. This uniqueness may now be extended to the chronic effects of ethanol.

Adolescent↗
PubMed2001

New solvent-producing Clostridium sp. strains, hydrolyzing a wide range of polysaccharides, are closely related to Clostridium butyricum.

Thirteen new Clostridium strains, previously isolated from soil and found to produce high amounts of solvents from glucose, hydrolyzed a great variety of alpha- and beta-glycans, including raw starch, xylan, pectin, inulin and cellulose. The sequences of the PCR-amplified DNA fragments containing the variable 3' part of one of the 16S rRNA genes were 99.5% identical. The macrorestriction pattern of two endonucleolytic digests of chromosomal DNA in the pulsed-field gel electrophoresis (PFGE) confirmed their high homogeneity on the DNA level. The complete 16S rRNA gene sequence of three selected strains was 99.8% identical to the 16S rRNA gene sequence from Clostridium butyricum and separates them from C. acetobutylicum. To the closely related four species of solventogenic clostridia a new group of strains has to be added, which has a great potential for the direct fermentation of biomass.

Biomass↗
PubMed2000

Prenatal choline supplementation alters hippocampal N-methyl-D-aspartate receptor-mediated neurotransmission in adult rats.

Manipulation of dietary choline levels in pregnant rats has been shown to result in enduring alterations in memory and hippocampal function of the offspring, but the mechanisms underlying these effects remain unclear. Hippocampal slices were prepared from adult rats that were offspring of dams fed control, choline supplemented, or choline deficient diets on days 12-17 of gestation. N-methyl-D-aspartate (NMDA) receptor-mediated population excitatory postsynaptic potentials (pEPSPs) were pharmacologically isolated and evoked using electrical stimulus pulses applied to s. radiatum of area CA1. Evoked NMDA receptor-mediated pEPSPs were enhanced in slices from prenatally choline supplemented relative to controls in both male and female rats. The greatest differences occurred at the low end of the input-output curve, among responses that were less than 60% of maximal. These results are discussed in the context of previous behavioral and electrophysiological studies.

Age Factors↗
PubMed2000

Isolation of mesophilic solvent-producing clostridia from Colombian sources: physiological characterization, solvent production and polysaccharide hydrolysis.

One hundred and seventy-eight new butanol-acetone producing bacteria related to saccharolytic clostridia were isolated from agricultural sources in Colombia and their fermentation potential was evaluated. Thirteen isolates produced more total solvents from glucose than Clostridium acetobutylicum ATCC 824. The isolates with the highest single solvent production were IBUN 125C and IBUN 18A with 0.46 mol butanol and 0.96 mol ethanol formed from 1 mol glucose, yielding 25. 2 and 29.1 g l(-1) total solvents, respectively, which is close to the maximum values described to date. Most of the new isolates produced exoenzymes for the hydrolysis of starch, carboxymethyl cellulose, xylan, polygalacturonic acid, inulin and chitosan. Together with the high efficiency of solvent production, these hydrolytic isolates may be useful for the direct fermentation of biomass. According to their physiological profile, the most solvent-productive isolates could be classified as strains of C. acetobutylicum, Clostridium beijerinckii, and Clostridium NCP262.

Clostridium↗
PubMed1997

Severe latex allergy after a vaginal examination during labor: a case report.

There has been an alarming increase in latex allergy, which can be a potential cause of occupational atopic disease. Physicians should be aware of this entity in high-risk groups and in patients with other allergies. A 32-year-old pregnant woman, with an allergy to orange juice, was first seen with a 39-week pregnancy in the labor room, where she had on two occasions a severe atopic reaction when examined with a latex glove. A latex allergy was suspected, and management with hydrocortisone resulted in remission of symptoms. Two hours later a vaginal delivery was performed with nonlatex, nonvinyl gloves. A week later immunoglobulin E antilatex antibodies determined by radioallergosorbent test were still positive at 585 IU. It is concluded that symptoms of latex allergy may develop in high-risk groups or in those with other known allergies. Because of the increasing frequency of this entity, physicians should take greater care and give more attention to the clinical history, as well as be aware of this possibility in these groups of patients.

Adult↗
PubMed1996

Toward optimizing the clinical utility of distortion product otoacoustic emission measurements.

This study examined the effect of primary stimulus level on the ability of distortion product otoacoustic emission (DPOAE) measurements to separate normal-hearing from hearing-impaired ears. Complete I/O functions were obtained for nine f2 frequencies on 210 people approximately evenly divided between normal hearing and hearing impaired. Clinical decision theory was used to assess both DPOAE amplitudes and DPOAE threshold as diagnostic indicators of hearing status. Moderate level primary stimuli elicited responses that separated normal from impaired better than either lower level or higher level stimuli. The two populations were differentiated for all frequencies above 500 Hz by DPOAE amplitude, given primary levels, L1 and L2, of 65 and 55 dB SPL. DPOAE threshold performed equally well, but threshold ambiguity in noise and longer testing times make it a less suitable DPOAE measure to use diagnostically.

Adolescent↗
PubMed1996

The use of cumulative distributions to determine critical values and levels of confidence for clinical distortion product otoacoustic emission measurements.

Distortion product otoacoustic emission (DPOAE) input/output functions were measured at nine f2 frequencies ranging from 500 to 8000 Hz in 210 normal-hearing and hearing-impaired subjects. In a companion paper [Stover et al., J. Acoust. Soc. Am. 100, 956-967 (1996)], L1-L2 was held constant at 10 dB, and L2 was varied from 65 to 10 dB SPL in 5-dB steps. Based upon analyses using clinical decision theory, it was demonstrated that DPOAE amplitudes for 65/55 dB SPL primaries (L1/L2) and DPOAE thresholds resulted in the greatest separation between normal and impaired ears. In this paper, the data for these two conditions were recast as cumulative distributions, which not only describe the extent of overlap between normal and impaired distributions, but also provide the measured value (i.e., the specific DPOAE amplitude or threshold) for any combination of hit and false alarm rates. From these distributions, confidence limits were constructed for both DPOAE amplitude and threshold to determine the degree of certainty with which any measured response could be assigned to either the normal or impaired population. For these analyses, DPOAE measurements were divided into three categories (a) response properties that would be unlikely to come from normal ears, (b) response properties that would be unlikely to come from impaired ears, and (c) response properties for which hearing status was uncertain. Based upon DPOAE amplitude measurements, the region of uncertainty, defined between the 95 percentile for impaired ears and the 5 percentile for normal ears, was relatively narrow for f2 frequencies ranging from 707 to 4000 Hz. For DPOAE thresholds, this region was relatively narrow for F2 frequencies ranging from 1414 to 4000 Hz.

Auditory Perception↗
PubMed1993

[Medical liability lawsuits according to specialties in Chile].

One-hundred forty-five cases of medical liability lawsuits originating in Chile from January 1987 to June 1991 and studied at the Medico Legal Service, were reviewed. A persistent increase in the number of accusations is observed in these five years. The principal medical specialties involved are Obstetrics and Gynecology (32%), General Surgery (18%), Internal Medicine (15%) and Pediatrics (9%). Seventy seven percent of implicated physicians were accredited specialists. Fifty percent of cases originated from Santiago and 60% from public hospitals. Eighty three percent of analyzed medical records were complete and in 70% the number of laboratory tests requested was adequate. The most frequent conditions that motivated lawsuits were acute fetal distress and puerperal sepsis in Obstetrics and Gynecology, acute abdomen and intra-operatory cardiac arrests in Surgery and sepsis in Internal Medicine. The risk of an unfavorable consequence that may lead to a lawsuit is present in every clinical condition, even in seemingly simple situations.

Adolescent↗
PubMed1993

[Medical and legal aspects of medical liability lawsuits].

The principal legal resolutions about medical liability lawsuits in Chile are analyzed. The causes for the accusations and for the increase in the number of suits in Chile, according to research performed by the authors, are described. An improvement in patient-physician relationships, a better alliance among physicians, a correct certification of medical specialties, the demand of adequate technological and humans resources to perform medical functions optimally, the supervision of medical work and the legal support and advice of medical societies are recommended strategies to prevent these lawsuits.

Chile↗
PubMed1990

A comparative trial of three agents in the treatment of acute migraine headache.

STUDY OBJECTIVES: A study was conducted to evaluate the relative efficacy of three non-narcotic agents, chloropromazine, lidocaine, and dihydroergotamine, in the treatment of migraine headache in an emergency department setting. DESIGN: The trial was randomized and single blinded. SETTING: The study was conducted in two university-affiliated EDs. TYPE OF PARTICIPANTS: All patients had an isolated diagnosis of common or classic migraine. INTERVENTIONS: Patients were pretreated with 500 mL (IV) normal saline before randomization. Study drugs as administered were dihydroergotamine 1 mg IV repeated after 30 minutes if the initial response was inadequate; lidocaine 50 mg IV at 20-minute intervals to a maximum total dose of 150 mg as required; or chloropromazine 12.5 mg IV repeated at 20-minute intervals to a total maximum dose of 37.5 mg as required. Patients were asked to grade headache severity on a ten-point scale before and one hour after the initiation of therapy. Follow-up by phone was sought the following day. MEASUREMENTS AND MAIN RESULTS: Of 76 patients completing the trial, 24 were randomized to receive chloropromazine, 26 to receive dihydroergotamine, and 26 to receive lidocaine. Reduction in mean headache intensity was significantly better among those treated with chloropromazine (P less than .005). Persistent headache relief was experienced by 16 of the chloropromazine-treated patients (88.9%) contacted at 12 to 24 hours follow-up compared with ten of the dihydroergotamine-treated patients (52.6%) and five of the lidocaine-treated group (29.4%). CONCLUSION: The relative effectiveness of these three antimigraine therapies appears to favor chloropromazine in measures of headache relief, incidence of headache rebound, and patient satisfaction with therapy.

Adult↗
PubMed1990

Response of non-migrainous headaches to chlorpromazine.

Chlorpromazine, given intravenously, is a useful agent in the treatment of acute migraine headaches. Patients with more serious conditions, however, may also respond to this medication. In this paper we report two patients who were initially diagnosed as having migraine headaches and treated with chlorpromazine. Both experienced temporary pain relief and it was only after repeated presentations to the emergency department that their conditions--a subarachnoid hemorrhage and a subdural hematoma--were accurately diagnosed. Because of this, caution must be exercised before re-treating within a short period of time, a patient with recurrent headache. Strong consideration must be given to an alternate diagnosis and such a diagnosis should be actively sought should there be any suspicion of a non-migrainous cause for headache. It is only by doing so that we may avoid missing more serious and life-threatening conditions such as those with which our patients presented.

Adult↗
PubMed1986

Management of the choking victim.

Current recommendations for the management of the choking victim have arisen from a long history of anecdotal experience and controversial experimental and clinical data. The author reviews the available literature on the various maneuvers and discusses the existing controversies. He also gives brief recommendations for the management of the choking victim.

Accidents, Home↗
PubMedDate not supplied

Beagle puppy model of perinatal asphyxia: blockade of excitatory neurotransmitters.

The N-methyl-D-aspartate receptor antagonist MK801 has been reported to prevent neuronal change in models of ischemia in adult animal systems. We studied the hypothesis that blockade of the N-methyl-D-aspartate receptor would prevent the depression of cerebral high-energy phosphates found in perinatal asphyxia without producing alterations in cerebral blood flow, and thus prevent neuropathologic damage. Newborn beagle puppies were anesthetized, tracheotomized, ventilated, and randomized to asphyxial insult (I = discontinuation of ventilatory support for 5 min) or no insult (NI) and drug treatment with MK801 (10 mg/kg intravenously) or an equal volume of saline (S). Puppies received MK801 or saline 15 min prior to I/NI. In S/I pups during insult, blood flow increased to brainstem structures but decreased elsewhere. MK801 had no effect on cerebral blood flow in either control or insulted puppies. 1H NMR studies demonstrated no effect of the MK801 on NI brains. Phosphocreatine levels were 1.7 +/- 0.1, 0.6 +/- 0.1, and 0.9 +/- 0.1 mmole/kg (mean: +/- S.D.) for the S/NI, S/I, and MK801/I pups, respectively. Cerebral lactate was 1.3 +/- 0.2, 3.0 +/- 0.7, and 2.0 +/- 0.4, respectively. The pH fell 0.8 units in the S/I puppies, compared to 0.4 units in the MK801/I puppies. We conclude that pretreatment with the N-methyl-D-aspartate receptor antagonist MK801 in part protects the developing brain against severe metabolic insult.

Animals↗