PubMed Health⌕ Search

Biomedical subjects

M C Diaz

Publications and source records attributed to M C Diaz.

At least 19 recordsLinked to original sources
PubMed2001

Composition of growth of Holstein calves fed milk replacer from birth to 105-kilogram body weight.

Sixty calves were assigned to a comparative slaughter study to determine the changes in composition of milk replacer-fed Holstein bull calves from birth to 105-kg body weight (BW). Six calves were slaughtered on day of birth and served as a baseline for comparison of compositional changes. Fifty-four calves were assigned to one of three treatments (18 calves per treatment). Calves were fed milk replacer containing 30% crude protein (CP) and 20% fat. Target growth rates for treatments 1, 2, and 3 were 500, 950, and 1400 g/d, respectively. Six calves from each treatment were slaughtered and analyzed for energy, nitrogen, ether extract, and ash when they reached 65, 85 and 105 kg of BW. Actual daily gains from birth to slaughter were 560, 973, and 1100 g, and net deposition of CP and fat were 140 and 44, 204 and 154, and 247 and 161 g/d for treatments 1, 2, and 3, respectively. Results were used to develop equations to predict retained energy [retained energy = (empty BW(0.223)) x (empty BW gain(1.32))], and retained protein, [retained protein = (184 x empty BW gain (kilograms/d)) + (17.2 x (retained energy)/empty BW gain] where retained energy is in Mcal/d, retained protein is in g/d, and empty BW and gain are in kilograms. The composition of gain observed was compared to predictions from the 1989 Dairy NRC and 1996 Beef NRC equations and demonstrated the equations do not represent the composition of gain in calves of this weight.

Animal Feed↗
PubMed2000

Analysis of ammonia-oxidizing bacteria from hypersaline Mono Lake, California, on the basis of 16S rRNA sequences.

Ammonia-oxidizing bacteria were detected by PCR amplification of DNA extracted from filtered water samples throughout the water column of Mono Lake, California. Ammonia-oxidizing members of the beta subdivision of the division Proteobacteria (beta-subdivision Proteobacteria) were detected using previously characterized PCR primers; target sequences were detected by direct amplification in both surface water and below the chemocline. Denaturing gradient gel electrophoresis analysis indicated the presence of at least four different beta-subdivision ammonia oxidizers in some samples. Subsequent sequencing of amplified 16S rDNA fragments verified the presence of sequences very similar to those of cultured Nitrosomonas strains. Two separate analyses, carried out under different conditions (different reagents, locations, PCR machines, sequencers, etc.), 2 years apart, detected similar ranges of sequence diversity in these samples. It seems likely that the physiological diversity of nitrifiers exceeds the diversity of their ribosomal sequences and that these sequences represent members of the Nitrosomonas europaea group that are acclimated to alkaline, high-salinity environments. Primers specific for Nitrosococcus oceanus, a marine ammonia-oxidizing bacterium in the gamma subdivision of the Proteobacteria, did not amplify target from any samples.

Ammonia↗
PubMed1997

Using scalarane sesterterpenes to examine a sponge taxonomic anomaly.

A parallel study was conducted on two Indo-Pacific foliose sponges. The first specimen contains 3-hydroxy-20,22-dimethyl-20-deoxoscalarin (2), while the second contains 3-oxo-20,22-dimethyl-20-dioxoscalarin 8 (3). The physical properties as well as X-ray results confirming the structure and stereochemical features of these compounds are presented first. The difficulty we encountered in the taxonomic identification of these species is also discussed. One of our specimens is identical to material considered by different taxonomists as either Phyllospongia vermicularis or Dysidea vermicularis. The other is identified as Carteriospongia sp. We outline that the parallel chemistry of these two specimens suggests that they are closely related taxonomically.

Animals↗
PubMed1996

Donor vascular grafts for arterial reconstruction in pediatric liver transplantation.

The authors compared the results of 48 orthotopic liver transplantations (OLT) in which revascularization was achieved with a conduit interposed between the receptor aorta and the graft (vascular graft [VG] group) with those obtained for 56 OLT performed during the same period (1991 to 1994) in which end-to-end anastomosis (EEA) of the hepatic arteries or celiac trunk was used (EEA group). In the VG group, the interposed conduits were the cadaveric iliac artery (37) the living-donor saphenous vein (3), or nonthrombosed conduits from previous transplants (8) (7 iliac arteries, 1 saphenous vein). There were significant differences between the two groups with respect to recipient age, recipient weight, the retransplant:first transplant ratio, the number of emergency transplantations, the use of reduced-size grafts, and intraoperative transfusion requirements. Twenty-nine grafts in the VG group (60.4%) and 43 in the EEA group (76.7%) currently are functioning. The actuarial 3-year graft survival rates are 60% and 71.5% for the VG and EEA groups (P < .05), respectively. The rate of arterial thrombosis did not differ between the two groups. The authors conclude that, although EEA of the hepatic artery is still the preferred revascularization technique for OLT, revascularization of the liver graft by conduit interposition is safe when EEA is not possible. Reutilization of the interposed conduit during retransplantation proved to be safe in the absence of hepatic artery thrombosis.

Anastomosis, Surgical↗
PubMed1996

Innovative techniques in pediatric liver transplantation: reduced-, split- and living-donor related liver transplantation.

In spite of the increased number of organ donations, the amount of livers available for pediatric patients does not meet requirements. In an attempt to expand the pool of grafts, several techniques of size reduction (RST) have been developed: reduced-liver transplantation (RLT), liver segment transplantation (LST), "split" liver transplantation (SLT) and living-donor liver transplantation (LDLT). The aim of this work is to study the contribution of these techniques to reduction of mortality in the waiting list and the increased risks that we inflict to our patients by using these procedures. We report our experience on RST in the last nine years (23 RLT, 5 LST, 2 SLT and 3 LDLT). More than a half of them were performed in an emergency. Overall survival in children with RST (67%) is similar to that of patients receiving a "whole graft" (74%). We did not find significant differences in the incidence of graft-related complications, only reintervention for abdominal bleeding was needed more often in the RST group (30%) than in whole graft group (24%). Our data confirm the safety of the RST procedures in the pediatric liver transplantation programs and they decrease the waiting-list mortality (2.5%) among the pediatric patients.

Adolescent↗
PubMed1996

[Reproducibility of nuclear grade in breast neoplasm. A multicenter experience].

Nuclear grade is considered a valuable prognostic factor in mammary carcinomas. Since the histological diagnosis of most of these tumors is made by "non expert" pathologists, it was considered interesting to find out the reproducibility of general pathologists to define the nuclear grade. In order to do this, a series of 15 mammary carcinomas, 10 of them randomly selected and 5 because they were considered difficult to classify for nuclear grade, were examined separately by 10 general pathologists. In a first round of observation, each one of them graded the cases according to their own criteria as used routinely, and for a second round they followed a written guide. An analysis of variance was applied to the data and no significant differences were found between observers, neither in the randomly selected cases nor in the total series. The written guide, surprisingly, instead of lowering the differences, increased them. Analysis of the individual performance of observers showed two of them having a great variation between both rounds of observation, and this was considered to influence the results of the whole group. Interobserver performance to discriminate high grade tumors (G3) from the rest, showed a good correlation in all the participants. These results allow us to conclude that in this series, examined by general pathologists, an acceptable reproducibility was observed, specially when high risk tumors were being identified.

Analysis of Variance↗
PubMed1995

Role of nitric oxide in control of prolactin release by the adenohypophysis.

Nitric oxide synthase-containing cells were visualized in the anterior pituitary gland by immunocytochemistry. Consequently, we began an evaluation of the possible role of NO in the control of anterior pituitary function. Prolactin is normally under inhibitory hypothalamic control, and in vitro the gland secretes large quantities of the hormone. When hemipituitaries were incubated for 30 min in the presence of sodium nitroprusside, a releaser of NO, prolactin release was inhibited. This suppression was completely blocked by the scavenger of NO, hemoglobin. Analogs of arginine, such as NG-monomethyl-L-arginine (NMMA, where NG is the terminal guanidino nitrogen) and nitroarginine methyl ester, inhibit NO synthase. Incubation of hemipituitaries with either of these compounds significantly increased prolactin release. Since in other tissues most of the actions of NO are mediated by activation of soluble guanylate cyclase with the formation of cyclic GMP, we evaluated the effects of cyclic GMP on prolactin release. Cyclic GMP (10 mM) produced an approximately 40% reduction in prolactin release. Prolactin release in vivo and in vitro can be stimulated by several peptides, which include vasoactive intestinal polypeptide and substance P. Consequently, we evaluated the possible role of NO in these stimulations by incubating the glands in the presence of either of these peptides alone or in combination with NMMA. In the case of vasoactive intestinal polypeptide, the significant stimulation of prolactin release was augmented by NMMA to give an additive effect. In the case of substance P, there was a smaller but significant release of prolactin that was not significantly augmented by NMMA. We conclude that NO has little effect on the stimulatory action of these two peptides on prolactin release. Dopamine (0.1 microM), an inhibitor of prolactin release, reduced prolactin release, and this inhibitory action was significantly blocked by either hemoglobin (20 micrograms/ml) or NMMA and was completely blocked by 1 mM nitroarginine methyl ester. Atrial natriuretic factor at 1 microM also reduced prolactin release, and its action was completely blocked by NMMA. In contrast to these results with prolactin, luteinizing hormone (LH) was measured in the same medium in which the effect of nitroprusside was tested on prolactin release, there was no effect of nitroprusside, hemoglobin, or the combination of nitroprusside and hemoglobin on luteinizing hormone release. Therefore, in contrast to its inhibitory action on prolactin release NO had no effect on luteinizing hormone release. Immunocytochemical studies by others have shown that NO synthase is present in the folliculostellate cells and also the gonadotrophs of the pituitary gland. We conclude that NO produced by either of these cell types may diffuse to the lactotropes, where it can inhibit prolactin release. NO appears to play little role in the prolactin-releasing action of vasoactive intestinal polypeptide and substance P, but mediates the prolactin-inhibiting activity of dopamine and atrial natriuretic factor.

Amino Acid Oxidoreductases↗
PubMed1995

Biliary atresia and the polysplenia syndrome: its impact on final outcome.

Up to 25% of babies with biliary atresia (BA) bear associated malformations that most often cluster in the polysplenia syndrome (PS). This article examines the impact of associated PS on the final outcome of the authors' BA patients and the necessary modifications of surgical technique during orthotopic liver transplantation (OLT) in these patients. The authors studied 88 consecutive infants with biliary atresia operated upon during the 10-year period between 1984 and 1993. Biliary drainage was provided by a Roux-en-Y hepaticojejunostomy. OLT was performed in 38. Eleven infants (12%) had three or more components of PS: malrotation (11), preduodenal portal vein (11), polysplenia (10), situs inversus (4), absent inferior vena cava (3), cardiac defects (2), and anomalous hepatic artery supply (2). Bile drainage was achieved in 7/11 infants (63% versus 48% for regular BA patients) 5 of whom (45% versus 31%) are jaundice-free with a mean follow-up of 105 months. Three patients received transplants (2 from living-related donor) and are alive and well with normal liver function after a mean follow-up of 35 months. Overall survival was 72% in the BA plus PS and 66% in the BA group (P = not significant [NS]). Results show that long-term bile drainage in these PS patients can be achieved at least as often as in other BA patients (45% versus 31%) (P = NS) and indicate that Kasai operation remains the best initial choice. When OLT becomes necessary, attention to vascular anatomy is required to determine the feasibility of reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Multiple↗
PubMed1995

Our first 100 consecutive pediatric liver transplants.

Orthotopic liver transplantation (OLT) is nowadays accepted as the best therapy for end-stage liver disease. The difficulties involved are even greater in children than in adults, and it is debatable whether exclusively pediatric programs are warranted. The aim of this paper is to analyze our experience at the Children's Hospital "La Paz", with the first consecutive 100 OLT in children, 61% of whom weighed less than 20 kg. Since 1986, 220 pediatric patients were evaluated as candidates, 100 OLT were performed in 78 patients and 13 died on the waiting list, currently maintained below 15 cases. Indications were: cholestasis (45), metabolic disease (18), fulminant hepatic failure (3), primary liver tumors (2) and cirrhosis (10). Mean age was 66 months (range = 7 to 216) with a mean weight of 21 kg (range = 6 to 60), twenty patients weighed less than 13 kilograms. OLT was performed by standard technique. Reduced or segmental grafts were necessary in 8 instances. Twenty-two patients were retransplanted and 2 received three grafts. Indications for retransplantation were: hepatic artery thrombosis (8), primary nonfunction (4), chronic rejection (7), portal thrombosis (2) and Budd-Chiari recurrence (1). Acute rejection was observed in 52 patients, and eight cases developed a chronic rejection. These episodes were treated with "bolus" of steroids, monoclonal antibodies (OKT-3) and FK-506. Surgical complications included: hepatic artery thrombosis 12%, portal vein thrombosis 3% and biliary fistula or stenosis 13%. The incidence of primary non-function was 7%. Actuarial survival rate at 5 years was 75%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Possible role of vasoactive intestinal peptide in the hyperprolactinemia induced by ethanol.

The effect of the blockade of endogenous VIP by injecting a specific rabbit anti-VIP serum (A-VIP) was studied in rats receiving an acute injection of ethanol. A-VIP administration decreased serum prolactin levels and reduced the hyperprolactinemia induced by ethanol. We also investigated the effect of the acute administration of ethanol on the concentration and release of VIP from the mediobasal hypothalamus. Ethanol decreased VIP concentration in the mediobasal hypothalamus, whereas it stimulated the in vitro K(+)-evoked release of VIP from this tissue. Conversely, ethanol increased VIP concentration in the anterior pituitary gland. The data indicate that VIP may be involved in the pituitary response to ethanol. The increased anterior pituitary VIP after ethanol may be due to an augmented release from the mediobasal hypothalamus.

Animals↗
PubMed1990

Scintigraphic measurement of oropharyngeal transit in man.

Scintigraphic studies of the oropharyngeal transit of a liquid bolus were performed in 15 healthy controls, 12 patients with symptoms of oral-pharyngeal dysphagia, and 13 patients with neuromuscular disease, who did not have dysphagia. Gamma camera imaging of the head, neck, and upper thorax was undertaken, in the lateral projection, during the swallowing of the radiolabeled bolus of water. Inspection of summed images permitted the selection of regions of interest (ROI) to represent the mouth, pharynx, and upper esophagus. Transit times between each ROI were calculated and compared. Significant prolongation of bolus transit time between the mouth and esophagus was present in both patients with and without dysphagia (0.59 +/- 0.38 sec and 0.33 +/- 0.7 sec; mean +/- SD, respectively) compared with controls (0.26 +/- 0.04 sec P less than 0.001, P less than 0.01, respectively, Mann-Whitney U test). Repeat studies in 25 individuals indicated that the transit measurements were more reproducible between swallows in normal subjects than in patients with symptoms. Deglutitive scintigraphy provides a noninvasive technique for the quantitative study of swallowing and its disorders.

Adult↗
PubMed1989

Estriol affects prolactin and LH secretion in rats.

The effects of estriol on serum prolactin (PRL) and LH levels, on the pituitary response to TRH and LHRH and on the synthesis and release of PRL from the anterior pituitary gland were investigated in female rats. The increase of serum PRL levels after estradiol administration was found to be associated with an increase of glutamic acid decarboxylase (GAD) and GABA-transaminase (GABA-T) in the hypothalamus. Thus, a study was carried out on the effects of estradiol and estriol on PRL secretion and on GAD, GABA-T and gamma-amino butyric acid (GABA) in the hypothalamus and the anterior pituitary. Under basal and TRH-stimulated conditions, estriol increased serum PRL levels, decreased basal serum LH levels, and increased the response to LHRH, in terms of LH release. Estradiol and estriol increased the synthesis and release of 3H-PRL from hemipituitary glands in incubations of pretreated animals. Both estrogens induced hyperprolactinemia, concomitantly with an increase of hypothalamic GAD and GABA-T activity. Estriol increased hypothalamic GABA concentration, but did not modify GABA concentration in the pituitary glands. Our results show that estriol, at relatively high doses, seems to be active in increasing PRL synthesis and release and in decreasing serum LH levels; it can also modify pituitary response to TRH and LHRH stimulation.

4-Aminobutyrate Transaminase↗
PubMed1987

The effect of prolactin on glutamate decarboxylase activity and GABA concentration in hypothalamic slices.

The effect of prolactin on the activity of GABA-related enzymes and GABA concentrations were studied in hypothalamic slices incubated in vitro. After short periods of incubation (up to 40 min), prolactin (0.25 micrograms/ml) added to the incubation medium produced a significant increase (21% at 20 min of incubation) in glutamic acid decarboxylase (GAD) activity in the hypothalamic slices. A higher concentration of prolactin (1.0 micrograms/ml) produced a slight but significant decrease (8% at 20 min of incubation) in hypothalamic GAD activity. However, after longer periods of incubation (over 8 hr), both doses of prolactin induced a sustained increase in hypothalmic GAD activity, a response which depends upon protein synthesis. No changes were observed in GABA-transaminase (GABA-T) activity of hypothalamic slices incubated in the presence of prolactin. Prolactin decreased GABA concentration in the hypothalami incubated for 10 hr and, at the same time, increased GABA release into the medium. These results indicate that prolactin modifies the synthesis and release of hypothalmic GABA and suggest the existence of a feedback mechanism that prolactin may exert directly at the hypothalamic level.

Animals↗