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Biomedical subjects

J D Luna

Publications and source records attributed to J D Luna.

At least 55 records · Page 3Linked to original sources
PubMed1996

Pyroglutamyl peptidase I levels and their left-right distribution in the rat retina and hypothalamus are influenced by light-dark conditions.

To evaluate the effects of light and darkness on pyroglutamyl peptidase I activity (pGluPI) and its left-right distribution, pGluPI was measured bilaterally in the retina and hypothalamus under selected light-dark schedules. Rats under a 12 h light-dark cycle were divided into four experimental groups. After the end of the 12 h dark period, the animals were kept two additional hours in darkness (group 1), or light (group 2). After the end of the 12 h light period, the animals were kept two additional hours in darkness (group 3), or light (group 4). Experiments were done in light or darkness depending on the 2 h period. In the retina, a previous 12 h light period led to higher values of enzyme activity than dark periods. Left-right predominance, however, depended on the previous 2 h period: the light period led to left predominance, whereas right predominance was found after the 2 h dark period. In the hypothalamus, a left predominance was found only in group 3. These results demonstrate that environmental light conditions influence pGluPI activity in the rat retina and hypothalamus.

Adaptation, Ocular↗
PubMed1996

Bone mineral density measured by dual X-ray absorptiometry in Spanish patients with insulin-dependent diabetes mellitus.

Previous studies suggest that low bone mass is a potential complication of insulin-dependent diabetes mellitus. Nevertheless, the factors that influence diabetic osteopenia are not well established. In order to evaluate the prevalence and magnitude of diabetic osteopenia and its association with clinical and metabolic variables, we studied 94 consecutive patients with insulin-dependent diabetes mellitus. Their age ranged from 20 to 56 years and duration of diabetes varied from 1 to 35 years. Bone mineral density (BMD) was measured by dual X-ray absorptiometry at lumbar spine and proximal femur and the values were expressed as z-score. The presence and extent of microvascular complications, degree of metabolic control, and other risk factors for osteoporosis were recorded and some biochemical markers of bone metabolism were assessed. Diabetic patients showed reduced BMD in all sites (lumbar spine: -0.89 +/- 1.21; femoral neck: -0.99 +/- 1.24; Ward triangle: -1.05 +/- 1.24; P < 0.0001). Of the 94 patients 19.1% met diagnostic criteria for osteoporosis. BMD correlated with body mass index in all sites and with the duration of disease in Ward's triangle. Presence and extent of diabetic complications were associated with lower BMD, as was smoking. No correlation was found between BMD and biochemical markers. In conclusion, osteopenia is a common complication in patients with insulin-dependent diabetes mellitus. Microvascular complications are a critical point in the progression of diabetic osteopenia. Other risk factors for osteoporosis (nutritional status and smoking) must be taken into account.

Absorptiometry, Photon↗
PubMed1996

Insulin resistance in patients with a recent diagnosis of coronary artery disease.

OBJECTIVE: To elucidate whether insulin resistance is present in coronary artery disease (CAD) at diagnosis and to study its relationship with other known cardiovascular risk factors. METHODS: We evaluated the incidence of insulin resistance in 40 newly diagnosed CAD patients. Fifteen healthy subjects were used as a control group. The patients and controls had no previous history of metabolic disorders, and were not being administered any medication that might have affected their insulin sensitivity. Immediately after diagnosis of CAD, a standard 75 g oral glucose-tolerance test (OGTT) and an insulin suppression test (IST) were performed on separate days. The IST consisted of a constant infusion of glucose, insulin and somatostatin for 150 min; insulin resistance was estimated by determining the steady-state plasma glucose (SSPG) concentrations during the last 60 min of the test. The insulin sensitivity index (ISI) was calculated by the formula ISI = (glucose infusion rate/SSPG]x10(3). RESULTS: Insulin resistance, defined by an ISI below the normal range derived from the control group, was present in 82.5% of the CAD patients. As a group, the patients with CAD displayed lower ISI (means +/- SD:29.23 +/- 11.23 versus 50.33 +/- 9.37 dl/kg per min, P < 0.001) than did controls. Serum triglycerides and uric acid were higher and high-density lipoprotein cholesterol levels were lower in patients than they were in controls. No differences were observed in fasting plasma insulin, glucose, total and low-density lipoprotein cholesterol concentration. An abnormal OGTT result was observed in 27 patients. The ISI was low in 88.8% of the patients with an abnormal OGTT result and in 69% of the 13 patients with a normal OGTT result. CONCLUSIONS: Insulin resistance and even impaired glucose tolerance are common findings in CAD at diagnosis. The changes in the lipid profile and in uric acid levels paralleled the changes in insulin sensitivity. These results suggest that insulin resistance might play a role in the development of coronary atherosclerosis and that its early diagnosis might be important in the prophylaxis of CAD.

Aged↗
PubMed1996

Intraconal amphotericin B for the treatment of rhino-orbital mucormycosis.

Rhino-orbital-cerebral mucormycosis is a disease that is frequently fatal. A 39-year-old man with diabetic ketoacidosis was referred to the authors' ophthalmic service with fever, orbital apex syndrome in the right eye, lethargy, and a black eschar in the palate. He was treated with systemic and local (intraconal) amphotericin B and his ketoacidosis was controlled; exenteration was not performed. Biopsy of the palate proved mucormycosis. Eighteen months later the patient was still alive and had a blind, anatomically preserved right eye with ptosis and intact extraocular muscle function without proptosis or pain. The authors propose this alternative means of treatment to achieve higher doses of the drug at the site of infection and better cosmetic and psychological results.

Adult↗
PubMed1996

Developmental changes of soluble and membrane-bound aspartate aminopeptidase activities in rat brain.

Specific soluble and membrane-bound aspartyl-naphthylamide hydrolyzing activities were assayed in brain subcellular fractions from rat fetuses (19-20 days of gestation), and from 1-week-old and 1-, 5- and 24-month-old rats. Both enzymatic activities showed a heterogeneous distribution, with highest concentrations mainly in the microsomal fraction. Membrane-bound activity was in most cases higher than soluble activity. With the exception of soluble activity in the nuclear and microsomal fractions, significant age-related changes were observed in all fractions for both enzymatic activities. Soluble activity showed a homogeneous developmental profile in most of the fractions, with the lowest levels in 1-month-old rats and the highest in 1-week and 5-month-old animals. However, changes in the microsomal fraction did not follow the pattern displayed by the rest of the fractions. No clear developmental profile in specific membrane-bound activity was observed, each fraction exhibiting a different sequence of changes. Whereas in 24-month-old-rats there was a significant increase in activity in homogenate, nuclear and microsomal fractions, a significant decrease was observed in the synaptosomal fraction. These results may reflect the functional status of the endogenous substrates of the enzymes.

Aging↗
PubMed1994

Contribution of endothelium derived relaxing factors to acetylcholine induced vasodilatation in the rat kidney.

OBJECTIVE: The aim was to evaluate the contribution of nitric oxide (NO) and endothelium derived hyperpolarising factor (EDHF) to the endothelium dependent, acetylcholine induced vasodilatation in isolated perfused rat kidney. METHODS: The renal response to acetylcholine was compared in phenylephrine preconstricted renal vasculature under basal conditions and after the infusion of N omega-nitro-L-arginine (L-NAME), an inhibitor of NO synthesis, and tetraethylammonium, a non-specific blocker of potassium channels that inhibits acetylcholine induced hyperpolarisation. These inhibitors were given alone and together. In another experiment, the renal response to acetylcholine was compared when the vasculature was preconstricted with phenylephrine or with 40 and 80 mM KCl under basal conditions and after the infusion of L-NAME. All experiments were done in the presence of indomethacin. RESULTS: Inhibition of NO generation with L-NAME reduced the vasodilator responses to acetylcholine by approximately 50%, and enhanced the response to sodium nitroprusside in the isolated perfused kidney preconstricted with phenylephrine. Infusion of tetraethylammonium also decreased the response to acetylcholine by approximately 50% and increased vasodilatation responses to sodium nitroprusside. The simultaneous administration of both inhibitors (L-NAME and tetraethylammonium) had a summational effect which almost completely suppressed acetylcholine induced vasodilatation. Increasing concentrations of extracellular potassium produced a dose related decrease in acetylcholine induced vasodilatation. These attenuated responses were almost abolished after the infusion of L-NAME. CONCLUSIONS: Our results suggest that the vasodilator response to acetylcholine in isolated perfused rat kidneys is subserved by EDHF and nitric oxide, both endothelium derived mediators participating to a similar extent.

Acetylcholine↗
PubMed1994

Vascular reactivity to vasoconstrictors in aorta and renal vasculature of hyperthyroid and hypothyroid rats.

Vascular reactivity to vasoconstrictors in relation to altered thyroid function was studied in two preparations: aortic strips and the isolated perfused kidney. To assess whether the possible alterations in vascular reactivity were restricted to a specific agonist or whether they involved the contractile system, receptor-mediated and nonspecific smooth muscle stimulants were used. Male Wistar rats were divided into three groups: control, hyperthyroid and hypothyroid rats. Aortic strips from hypothyroid rats were less sensitive to phenylephrine and KCl when the data were expressed in absolute values or as percentages of the maximum responses. Sensitivity and reactivity in strips from hyperthyroid rats were similar to those observed in control strips. Renal vasculature obtained from hypothyroid rats also showed a markedly reduced sensitivity to phenylephrine, with normal maximal responses. The response to vasopressin at 3-10(-11) mol/l was also decreased, as was the reactivity to barium chloride. In contrast, renal vasculature of hyperthyroid rats showed markedly enhanced reactivity to all agonists: the concentration-response curves were characterized by a similar threshold and a greater maximal response. These results demonstrate that hypothyroidism is accompanied by a marked decrease in sensitivity to vasoconstrictors in large arteries as well as in resistance vessels. This decrease may be secondary to a generalized alteration in the contractile system of vascular smooth muscle cells and may play a role in the decreased blood pressure in these animals. In contrast, isolated perfused kidneys of hyperthyroid rats showed increased vascular reactivity to vasoconstrictors, which may play a role in the maintenance of elevated blood pressure in these animals.

Animals↗
PubMed1994

Comparison of the CAGE questionnaire versus some biochemical markers in the diagnosis of alcoholism.

We have compared the individual sensitivity, specificity and predictive value of the CAGE questionnaire, plasma levels of ethanol and acetate, mean corpuscular volume (MCV), gamma glutamyl transferase (GGT), and glycosylated haemoglobin (Hb A1c) in a group of 50 healthy non-alcoholic controls and 31 patients with non-alcoholic liver disease (Group I), and in a second group of 40 alcoholic patients (Group II). Taken individually, the CAGE questionnaire was the most efficient (96% sensitive and 92% specific), followed by plasma levels of acetate (74% sensitive and 85% specific), MCV (64% sensitive and 91% specific) and GGT (72% sensitive and 80% specific). Hb A1c did not show any statistically significant difference between alcoholics and non-alcoholics and thus is of no use as a screening test for the diagnosis of alcoholism. Furthermore, we attempted to design a discrimination procedure to separate alcoholics from controls and patients with non-alcoholic hepatic diseases using a combination of the most promising tests. The most powerful discrimination model was constructed with the four questions of the CAGE questionnaire. The percentage of correct classifications using this model was 99% from Group I (specificity) and 90% from Group II (sensitivity). The CAGE questionnaire was itself so useful as a discriminant in our sample that no increased diagnostic efficacy was noticed on adding any of the other tests. Using objective variables (MCV, acetate and GGT) as discriminants, we could correctly classify 96% of subjects from Group I (specificity) and only 64% from Group II (sensitivity).

Adolescent↗
PubMed1993

Chronic insulin treatment in rats: evidence against a role for insulin as a pressor agent.

1. The present study was undertaken to test whether insulin acts as a pressor agent and causes hypertension in rats. 2. Insulin at doses of 10 or 100 units day-1 kg-1 was administered daily by subcutaneous injection to normal rats for 6 weeks. As it has been suggested that sodium retention plays a major role in the putative hypertensive activity of this hormone, insulin was also administered to saline- (1% NaCl) drinking rats according to the same protocol. Water- and saline-drinking rats served as controls. 3. After 6 weeks of insulin treatment, the mean arterial blood pressure did not increase in any of the insulin-treated or the insulin-salt-treated groups. However, in both insulin-salt-treated groups, absolute and relative ventricular and renal hypertrophy with increased ventricular water content as well as increased urine output with reduced osmolality were observed. 4. All insulin-treated groups showed increased plasma levels of glucose, insulin and antidiuretic hormone when compared with their respective controls. 5. These results demonstrate that chronic insulin treatment did not increase blood pressure in rats, even when drinking water was supplemented with NaCl, and suggest that a polyuria-polydipsia syndrome was present in both insulin-salt-treated groups. Moreover, increased plasma levels of antidiuretic hormone were observed in all insulin-treated groups.

Animals↗
PubMed1993

Influence of the doctor's gender in the satisfaction of the users.

This study was carried out in the framework of a wider research project concerning the degree of patient satisfaction with the various types of primary health care. We have studied the relationship among the gender of the doctor, the gender of the patient and the type of primary health care center involved. In 1 type of primary care center (health centers) the medical staff work as a team, whereas in the other (ambulatory care services), the doctor works alone. The survey was conducted among 86 doctors and 860 patients from urban areas in Andalusia, Spain. The degree of patient satisfaction was tested on Likert scales. Both male and female patients attended by female doctors were more satisfied than those attended by male doctors (P < 0.005). Both male and female patients were attended in equal proportions by both male and female doctors (P > 0.20). Overall patient satisfaction values were not affected by the patient's gender (P > 0.40). In comparing overall satisfaction among patients according with the doctor's gender and type of primary health care center, there was a greater degree of satisfaction with female doctors working in health centers (P < 0.01) and no difference existed in ambulatory care services in this area.

Adult↗
PubMed1993

[Acetate metabolism: experimental study].

Plasma levels of ethanol and acetate, which is the end product of hepatic ethanol oxidation, have been studied in 60 rats. Animals were divided into two groups: 1) Control rats, and 2) Alcohol-treated rats. Ethanol and acetate were measured without any previous handling (endogenous levels) and after intraperitoneal injection of a single dose of ethanol. Blood specimens were taken at 30, 60, 120, 180 and 240 minutes after ethanol injection. Plasma levels of ethanol and acetate were performed by Head Space Gas Chromatography. Alcohol-treated animals had higher plasma acetate levels than control ones. There were statistically significant differences for acetate between both groups of rats at 0, 30, 120 and 180 minutes.

Acetates↗
PubMed1991

Urinary excretion of digoxin-like immunoreactive factor and arginine-vasopressin in rats after several osmotic loads.

Urinary digoxin-like immunoreactive factor (DLIF), arginine-vasopressin (AVP) and other urinary parameters were investigated under normal conditions and after the i.p. injection of the following solutions: distilled water, isotonic and hypertonic NaCl, NaHCO3, KCl and urea, at a rate of 3 ml/100 g body weight. The measurement of digoxin-like immunoreactivity by two different radioimmunoassays showed that DLIF was stimulated by all volume loads regardless of the presence or absence of osmolar compounds. This dissociation between DLIF and urinary sodium excretion suggests that DLIF may not constitute the natriuretic hormone. Moreover, a dissociation between DLIF and AVP excretion also were found, which speaks against the hypothesis of a common mechanism of stimulation for both substances.

Animals↗
PubMed1991

Effect of penicillin and chloramphenicol on the growth and endotoxin release by N. meningitidis.

The action of two antibiotics, penicillin and chloramphenicol, on bacterial growth and endotoxin liberation was studied in 18 strains of Neissevia meningitidis isolated from blood and CSF of patients with meningococcal infections. The antibiotics were administered both separately and in combined form in doses equivalent to 1 MIC and 100 MIC. Penicillin was found to produce a faster and more intense bactericidal effect than chloramphenicol during the first hour, whereas at 12 h these differences were not significant. This could explain the initial worsening observed in some infected patients when large doses of penicillin are administered. An increased liberation of endotoxin after adding penicillin was observed in six of the strains studied, whereas the remaining 12 did not show significant increases. The six strains (belonging to serogroup B) were known to have an enhanced capacity for spontaneous endotoxin liberation.

Chloramphenicol↗
PubMed1991

Urinary excretion of digoxin-like immunoreactive factor and arginine-vasopressin in hyper- and hypo-thyroid rats.

1. Urinary excretion of digoxin-like immunoreactive factor and arginine-vasopressin and other parameters related to salt and water metabolism were studied in hyper- and hypo-thyroid rats after different tests. 2. Urinary excretion of arginine-vasopressin was increased in hyperthyroid and reduced in hypothyroid rats with respect to controls, in response to water deprivation or a hypertonic saline load. 3. Control and hypothyroid rats showed the highest urinary excretion of digoxin-like immunoreactive factor after a hypertonic saline load. However, hyperthyroid rats had the highest urinary levels of digoxin-like immunoreactive factor under normal conditions. 4. From these results it is suggested that: (a) hyper- and hypo-thyroid rats exhibit hyper- and hypo-responsiveness of arginine-vasopressin secretion to osmotic stimuli, respectively; (b) an unidentified digoxin-like immunoreactive factor measured in unextracted rat urine may be related to diuresis and natriuresis in control and hypothyroid rats; however, dissociation between this factor and natriuresis is observed in hyperthyroid rats.

Animals↗
PubMed1990

Plasmatic levels of atrial natriuretic peptide (ANP) in drowning. A pilot study.

Bodies found in water may cause problems for forensic pathologists who have to differentiate drowning from postmortem immersion or fresh from salt water drowning. The exact physiopathology of drowning is still controversial and complementary tests can not exactly establish the exact cause of death if macroscopic findings at autopsy are not conclusive. We have employed atrial natriuretic peptide (ANP) as a marker in an experimental series of fresh and salt water drowning, comparing their results with a non-drowned control series. There are differences between the plasma basal levels of the control series (79 pg/ml) and the levels in animals drowned in fresh water (358 pg/ml, P less than 0.001) and between control and rabbits drowned in salt water (190 pg/ml, P less than 0.001). According to these values, there are also differences between fresh and salt water drowned animals (P less than 0.001). We propose this peptide as a new marker in cases of drowning, with the ability to differentiate drowning from postmortem immersion and fresh from salt water drowning.

Analysis of Variance↗
PubMed1990

Urinary excretion of digoxin-like factor (DLF) and ADH during DOCA-salt and Goldblatt 2 kidney-1 clip hypertension development.

Urinary digoxin-like factor, ADH, sodium and potassium excretion and urine osmolality were studied during the development of two pathogenically different models of hypertension, DOCA-salt (low-renin) and Gold-blatt 2 kidney-1 clip (renin-dependent). Urinary digoxin-like factor was increased in rats that were given saline (NaCl 1%) to drink, uninephrectomized-salt and DOCA-salt rats, with no significant differences between the two groups urinary ADH was elevated in DOCA-salt rats during the study, compared with uninephrectomized-salt rats. Urinary digoxin-like factor and urinary ADH were not significantly modified in Goldblatt 2 kidney-1 clip and sham-operated rats. In addition, positive correlations between digoxin-like factor urinary excretion and urinary ADH and also with sodium urinary excretion were found. These data suggest that: a) digoxin-like factor and ADH could play a role in the pathogenesis of DOCA-salt but not in Goldblatt 2 kidney-1 clip hypertension. b) A common mechanism may stimulate ADH and digoxin-like factor simultaneously. c) Digoxin-like factor plays a role in the control of urinary sodium excretion.

Animals↗