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Biomedical subjects

A Calderon

Publications and source records attributed to A Calderon.

At least 19 recordsLinked to original sources
PubMed2001

gamma-Aminobutyric acid (GABA)--A function and binding in the paraventricular nucleus of the hypothalamus in chronic renal-wrap hypertension.

The goal of this study was to determine whether gamma-aminobutyric acid (GABA)ergic transmission and GABA binding are altered in chronic renal-wrap hypertension. Three groups of hypertensive and sham-operated rats were prepared for separate protocols. Four weeks later, the animals were prepared with femoral artery catheters for the measurement of mean arterial pressure. In all groups, blood pressure was significantly higher in the renal-wrapped animals. In the first study, bilateral microinjection of the GABA-A antagonist, bicuculline (50 pmol/site), into the paraventricular nucleus of the hypothalamus (PVN) caused a greater increase in arterial pressure (21.9+/-1.4 versus 16.7+/-1.8 mm Hg, P<0.05) and heart rate (135+/-15 versus 98+/-12 bpm, P=0.064) in hypertensive rats. [(3)H]Flunitrazepam was used to measure binding to the GABA-A receptor. Magnocellular neurons and the adjacent medial parvicellular neurons had more intense binding compared with the remainder of the PVN. B(max) was greater for the higher density binding area; the K(d) value was less in the high-density region. There were no differences in these parameters between normotensive and hypertensive animals. Competitive reverse transcription-polymerase chain reaction was used to measure the expression of mRNA for the alpha(1) subunit of the GABA-A receptor. No difference was observed in the mRNA between renal-wrapped and sham-operated rats. In summary, inhibition of GABA-A receptors in the PVN is augmented in the chronic phase of hypertension and is unrelated to a change in the expression of the number or affinity to the receptor. These findings suggest that the greater GABAergic activity is the result of an increase in GABA release in the PVN in chronic renal-wrap hypertension.

Animals↗
PubMed1999

Managing depressed and suicidal geriatric patients: differences among primary care physicians.

This study examined differences by specialty of primary care physicians in managing suicidal and depressed geriatric patients. A probability sample of 300 Illinois physicians drawn from the American Medical Association Physician Masterfile was surveyed. Significant differences were found between specialties in estimates of the prevalence of psychiatric disorders; use of assessment procedures, treatment approaches, and referrals; perceptions of obstacles to providing mental health care; and confidence in diagnosing and treating depression and suicidality. Meeting the mental health needs of the rapidly growing older population will require a greater emphasis on geriatric mental health and consistency across primary care specialties.

Adult↗
PubMed1998

Differential diagnosis of NPH and brain atrophy assessed by measurement of intracranial and ventricular CSF volume with 3D FASE MRI.

Differential diagnosis of NPH and brain atrophy is sometimes difficult. Recently, a new method using MRI was introduced as a noninvasive, direct technique for the measurement of intracranial CSF volume. Using this new technique, we measured the intracranial and ventricle CSF volume in patients with enlarged ventricles in order to differentiate between NPH and brain atrophy. Ten healthy volunteers (control group) and 21 patients with enlarged ventricles were enrolled in this study. Eleven out of 21 patients were clinically diagnosed as having NPH (shunted group) and the remaining 10 patients were considered to have cerebral atrophy (non-shunted group). Intracranial and ventricular CSF volume in each case were measured by 3D FASE (Fast Asymmetric Spine-Echo) MR imaging sequence with region growing method. Ventricular/intracranial CSF volume ratio was also calculated. Ten out of 11 patients showed improvement in clinical symptoms and/or dementia scale after shunting. Our results clearly indicate that the ventricular volume in the shunted group was enlarged and that the ventricular/intracranial CSF ratio was significantly high. Thus we concluded that enlarged ventricle with high ventricular/intracranial CSF volume ratio strongly suggests NPH.

Adult↗
PubMed1997

Firearm suicide among older women in the U.S.

Contrary to the common view that older women (65+) in the United States use suicide methods that have relatively low potential for death, firearms have become the most common suicide method in this group. The present study examines the association between demographic and geographic factors and the use of firearms vs other suicide methods. Data were derived from the National Center for Health Statistics (NCHS) Mortality Detail Files (1989-1991). Results from a logistic regression analysis indicate that among white women 65 and over who died by suicide in 1989-1991, the risk of using firearms varied significantly across demographic and geographic subcategories of the population. The following characteristics among women were significantly more likely to be associated with the use of firearms as a suicide method: ages 65-74, married, of lower educational attainment, in nonmetropolitan areas, and in the South. Research is needed to assess the effects of limiting firearms on the growing proportion of firearm-related suicides among older women.

Age Factors↗
PubMed1995

A precise and fast temperature mapping using water proton chemical shift.

A new temperature measurement procedure using phase mapping was developed that makes use of the temperature dependence of the water proton chemical shift. Highly accurate and fast measurements were obtained during phantom and in vivo experiments. In the pure water phantom experiments, an accuracy of more than +/- 0.5 degrees C was obtained within a few seconds/slice using a field echo pulse sequence (TR/TE = 115/13 ms, matrix = 128 x 128, number of slices = 5). The temperature dependence of the water proton chemical shift was found to be almost the same for different materials with a chemical composition similar to living tissues (water, glucide, protein). Using this method, the temperature change inside a cat's brain was obtained with an accuracy of more than +/- 1 degree C and an in-plane resolution of 0.6 x 0.6 mm. The temperature measurement error was affected by several factors in the living system (B0 shifts caused by position shifts of the sample, blood flow, etc.), the position shift effect being the most serious.

Animals↗
PubMed1993

Prevention of apical periodontal ligament pain: a preliminary report of 100 vital pulp cases.

A preliminary study was conducted in a private practice office to determine the incidence of postoperative pain in 100 vital pulp cases. An ophthalmic dexamethasone-neomycin solution was introduced within the root canal during the complete cleaning and shaping procedure with the purpose of premedicating and preventing apical periodontal ligament inflammation and pain. The postoperative pain outcome was compared between cases premedicated with intracanal dexamethasone-neomycin solution alone and in combination with an oral administration of Mesulide. Moderate pain was reported in 10 cases and tooth sensitivity in 13. The clinical results indicated no report of severe pain.

Adolescent↗
PubMed1993

Amoebological study of the atmosphere of San Luis Potosi, SLP, Mexico.

A one year round survey was conducted for isolation of free living amoebae (FLA) in the city of San Luis Potosi, (SLP), Mexico, which is placed in a desert environment. Samples were taken by modified impinger method and cultivated in laboratory conditions for FLA isolation following a week period of rehidration. 57 strains were isolated, 39% belonged to Acanthamoeba genus (which is important because it bears opportunistic pathogens that produce amoebic keratitis and granulomatous amoebic encephalitis in humans), 16% to Hartmannella, 9% to Vahlkampfia and the other proportion was divided among 6 other genera. The isolations were more abundant during dry season and the main genera were present in all four stands. The difference among them was the species variety which is discused as connected with abundance of organic wastes and lack of urbanization near the stations.

Air Microbiology↗
PubMed1991

Chronic dissection of the anterior tibial artery leading to acute aneurysmal dilatation.

We present a clinical case of chronic dissection of the anterior tibial artery leading to acute aneurysmal dilatation. Our patient, a 22-year-old man, had a history of trauma at the middle third of his left leg. Because of impending ischemia, he was diagnosed by emergency arteriography. We ligated the proximal and distal ends of the dissection and used a reversed saphenous vein for a short end-to-end bypass. Although the evolution of this dilatation had been silent, its clinical presentation was spectacular. The case is worthy of attention because of its extreme rarity, both as a dissection of a peripheral artery caused by trauma and as an aneurysmal dilatation at tibial level.

Journal Article↗
PubMed1990

Predictors of Haitian-American infant development at twelve months.

Perinatal and early childhood influences on the development of 66 Haitian-American children were examined as part of an ongoing home visiting program. Although all participants were impoverished, approximately two-thirds lived in an urban setting with some access to social and health services, while one-third lived in a rural farmworkers' community where housing and services were sharply substandard. Measures used to examine the development of infants in these 2 settings included birthweight, household crowding, parental contributions to the child-rearing environment (the HOME), and developmental progress at 12 months on the Bayley Scales of Infant Development. Results showed that the urban sample was advanced on the Mental Development Index of the Bayley Scales. Regression analyses showed birthweight and the HOME score measuring child-rearing environment to be significant predictors of mental development, while psychomotor development was related to birthweight and household crowding. The results indicate that even within this disadvantaged Haitian entrant population, environmental differences exist that influence infant development in subtle but significant ways.

Adolescent↗
PubMed1989

Pathogenic amoebae in natural thermal waters of three resorts of Hidalgo, Mexico.

In a search for free-living amoebae, seven water samples from three thermal water bathing resorts in Tecozautla, Hidalgo, were analyzed during December 1984. The samples were concentrated by filtration and centrifugation, and inoculated later on monoxenic and axenic media. The identification of the isolates was performed by morphology and isoelectric focusing of isoenzymes and total proteins. Thirty-three strains of free-living amoebae belonging to the genera Naegleria, Acanthamoeba, and Willaertia were isolated. Twenty of these strains belonged to the Naegleria genus, 16 of them were classified as Naegleria spp., and 2 were classified as Naegleria lovaniensis. Noteworthy was the finding of two pathogenic strains of the species Naegleria australiensis. N. australiensis and N. lovaniensis may be considered good indicator organisms, since they live in the same environmental conditions as N. fowleri, the agent of primary amoebic encephalitis (PAM). On the other hand, amoebae other than Naegleria were isolated and identified as Acathamoeba castellanii (two strains), and Acanthamoeba lugdunensis (one strain), which proved to be pathogenic when tested in mice. Nine more pathogenic strains of the genus Acanthamoeba spp. were isolated together with one strain of Willaertia magna, a thermophilic nonpathogenic amoeba. The chlorination and periodical surveillance of water resorts like the one studied is recommended, in order to prevent the appearance of more cases of PAM or other human diseases associated with pathogenic Acanthamoeba spp.

Amoeba↗
PubMed1987

[Failure of gastric lavage in severe drug poisoning. Value of esophagogastric fibroscopy].

A case is reported of massive drug self-poisoning (more than 200 pills associated with slices of oranges) in which repeated gastric lavage failed to empty the stomach. An attempt to split up the amalgamated pills, adherent to the gastric mucosa, by fibre-optic gastroscopy failed and a gastrotomy was required. Endoscopy together with gastric lavage is indicated in certain situations to quickly empty the stomach and so shorten the course of the poisoning. Indications are the large number of pills swallowed, a poor result of the treatment, a worsening of the clinical condition despite treatment, and three positive gastric toxicological assays within the first 24 h.

Amitriptyline↗
PubMed1987

Subsarcolemmal vermiform deposits in skeletal muscle, associated with familial cardiomyopathy: report of two cases of a new entity.

Distinctive subsarcolemmal acid phosphatase-positive crescents were found in many muscle fibers of triceps muscle biopsies from 2 siblings with cardiomyopathy. The crescents appeared as dense osmophilic material in irregular vermiform arrays on electron microscopy. However, both patients had clinically normal skeletal muscle function. These 2 cases are believed to represent a rare familial myopathy affecting cardiac and skeletal muscle.

Cardiomyopathies↗
PubMed1985

[Inhibition of postoperative muscular proteolysis by sodium alpha-ketoisocaproate: does a dose-effect relation exist?].

The inhibitory effect of branched chain amino acids on muscle protein breakdown has been attributed to the ketoanalogue of leucine, alpha-ketoisocaproic acid. In an attempt to demonstrate a possible dose-response relationship for ketoleucine, the postoperative protein breakdown (using urinary excretion of 3-methylhistidine, creatinine and nitrogen) was evaluated in 29 patients undergoing gynaecological surgery. They were randomly assigned to one of the following groups: group A (ten patients) received 3 g of glucose per kilo and per day, group B (ten patients) received glucose + 100 mg X kg-1 X d-1 of ketoleucine and group C (nine patients) glucose + 200 mg X kg-1 X d-1 of ketoleucine. The study was performed over a period of 72 h. The 3-methylhistidine/creatinine ratio was significantly lower in groups B and C than in group A (respectively 28.47, 28.07 and 32.08). These results confirmed the inhibitory effect of ketoleucine on muscle protein breakdown. However there was no difference between group B and group C. In conclusion, this study did not demonstrate a dose-response relationship for ketoleucine in moderate postoperative catabolism.

Adult↗
PubMed1984

Effect of leucine or ketoleucine on nitrogen metabolism in postoperative patients receiving energy substrate.

It has been shown that ketoisocaproate (KIC) spares nitrogen (N) in fasting postoperative patients while leucine does not. The aim of the present study was to determine if KIC when compared with leucine, decreases nitrogen excretion in postoperative patients receiving energy substrate. Thirty patients undergoing gynecological surgery (hysterectomy with or without lymphadenectomy) were randomized to receive for the first 3 postoperative days one of the following I.V. solutions per kilo and per day: 3 g glucose (group A) 3 g glucose + 90 mg Leucine (group B), 3 g glucose + 100 mg ketoleucine (group C). The output of 3 methylhistidine (3 MEH), total nitrogen and creatinine were measured daily. Although muscle protein breakdown measured as 3 MEH/creatinine molar ratio was significantly reduced in group C as compared with A and B, total nitrogen and creatinine did not differ significantly in A, B and C. Thus, the metabolic effects of KIC in postoperative patients are appreciably influenced by glucose infusions and the usefulness of KIC infusions in such patients needs further study.

Journal Article↗
PubMed1982

Ovarian activity in the mare between latitude 15 degrees and 22 degrees N.

Ovarian activity, as measured by the presence of small (10-15 mm diam.), medium (15-30 mm) and large (greater than 30 mm) follicles, corpora haemorrhagica and corpora lutea (CL), was determined in a total of 3584 ovaries during 1 year using post-mortem specimens. There were significant correlations of the incidence of ovulated follicles (ovulations), large and medium follicles (P less than 0 . 001) and of the mean number of small follicles (P less than 0 . 05) per mare with respect to season. The yearly averages of ovulated, large and medium follicles were 30 . 1, 13 . 9 and 73 . 9%, respectively, and the mean number of small follicles per mare was 2 . 0. The mean incidence of inactive ovaries throughout the year was 21 . 2%. The adjusted sinusoidal curves remained above their own yearly average from April to October (ovulations), March to September (large follicles), February to September (medium follicles) and January to July (small follicles), and below its yearly average from March to September (inactive ovaries). The mean incidence of multiple ovulations was 11 . 9%. No significant differences were found between the activities of the right and left ovaries. It was concluded that the mare shows a seasonal reproductive pattern near the equator in the northern tropical zone.

Animals↗