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Biomedical subjects

M Hernandez

Publications and source records attributed to M Hernandez.

At least 127 records · Page 7Linked to original sources
PubMed1989

Klebsiella bacteremia. A 10-year review in a cancer institution.

A total of 368 episodes of Klebsiella bacteremia occurred in 330 cancer patients, representing a rate of four episodes per 1000 hospital admissions. Eighty-eight percent of these infections were acquired nosocomically and 58% of the patients received antibiotics during the preceding 10-day period. There was pulmonary infection in 24% of the patients, shock in 25%, and disseminated intravascular coagulation in 7%. The overall response rate was 69%. Response rates were significantly lower among patients with shock (25% versus 83%), hemorrhage (29% versus 76%), and pneumonia (37% versus 79%). The combination of a cephalosporin plus an aminoglycoside produced the highest response rate (79%). Klebsiella sp continue to be an important cause of infection in patients with cancer.

Adolescent↗
PubMed1989

Modulation of 17 alpha-hydroxylase/C17,20-lyase activity in porcine theca cells.

The major source of ovarian androgen is the theca cells. Androgens are produced by the conversion of progestins by the 17 alpha-hydroxylase/C17,20 lyase enzymatic system (lyase). The 3 beta-hydroxysteroid dehydrogenase and aromatase enzymes in the theca cells are modulated by gonadotropins as well as by steroids produced locally. Therefore, the combined effects of hCG plus progesterone, estradiol, or dihydrotestosterone (DHT) on microsomal lyase activity in theca cells from large and medium-sized follicles were determined. Theca cells (3 x 10(6) cells/6 ml/well) were cultured in Medium 199 (M199) containing only insulin (10 micrograms/ml) and transferrin (5 micrograms/ml). At 24 h, theca cells were treated with M199, hCG (15 ng/ml), progesterone, estradiol, or DHT (100 ng/ml) or a combination of hCG + one of the three steroids. Media were removed at various times of culture (27-72 h) and levels of androgen determined by RIA. Microsomes were incubated with 1 microCi [3H]progesterone +0.5 mM NADPH and radioactive conversion products were measured after purification by thin layer chromatography. Administration of progesterone, estradiol, or DHT alone had little effect on lyase activity in theca cells from medium-sized follicles whereas the addition of hCG alone significantly increased lyase activity in these cells. However, concomitant addition of any steroid with hCG inhibited the increase in lyase activity after the addition of hCG alone. Theca cells from large porcine follicles had a higher basal level of lyase activity compared to theca cells from the smaller follicles. Lyase activity in theca cells from large follicles was enhanced by progesterone; estradiol was inhibitory. DHT initially stimulated lyase activity in theca cells from large follicles, but was inhibitory later in culture. In contrast to its marked effect on theca cells from medium follicles, hCG had only a small effect on lyase activity in theca cells from large follicles. Thus, thecal lyase activity increased as the follicle matured, providing more androgen substrate for the production of estrogen. Lyase activity in theca cells of medium follicles appears to be regulated predominantly by gonadotropin from the pituitary while intraovarian regulation of lyase activity by steroids may be more important in larger follicles.

Aldehyde-Lyases↗
PubMed1989

Synthesis of congeners and prodrugs. 3. Water-soluble prodrugs of taxol with potent antitumor activity.

Taxol has shown good in vivo antitumor activity in a number of test systems. The formulation of taxol for antitumor testing has been difficult. Esterification at either C-2' or C-7 resulted in loss of in vitro tubulin assembly activity but not cytotoxicity. These observations suggested that esters at C-2' and/or C-7, which would tend to promote water solubility, might serve as useful prodrugs of taxol. The reaction of taxol with either succinic anhydride or glutaric anhydride in pyridine solution at room temperature gave the crystalline mono 2'-adducts 1b and 1f, respectively. Salts of these acids (1b, 1f, 1i) were formed by the addition of 1 equiv of the corresponding base, followed by evaporation and/or freeze-drying of the solvent(s). The salts had improved antitumor activity as compared to the free acids. The triethanolamine and N-methylglucamine salts showed greatly improved aqueous solubility and were more active than the sodium salts. The glutarate series was preferred because of the higher activity and the higher yields obtained. 2'-Glutaryltaxol (1f) was coupled with 3-(dimethylamino)-1-propylamine, using CDI, to form in excellent yield the amino amide 1o. The hydrochloride salt (1p) showed good solubility and was extremely potent and active. At 10 mg/kg, in the B16 screen, 1p gave a T/C of 352 with 5 out of 10 cures. In the MX-1 breast xenograft assay, this prodrug gave values of -100 at doses of 40 and 20 mg/kg, with all live animals being tumor free.

Alkaloids↗
PubMed1989

Optic nerve regeneration in adult fish and apolipoprotein A-I.

Fish optic nerves, unlike mammalian optic nerves, are endowed with a high capacity to regenerate. Injury to fish optic nerves causes pronounced changes in the composition of pulse-labeled substances derived from the surrounding non-neuronal cells. The most prominent of these injury-induced changes is in a 28-kilodalton (kDa) polypeptide whose level increases after injury, as revealed by one-dimensional gel electrophoresis and autoradiography. The present study identified as apolipoprotein A-I (apo-A-I) a polypeptide of 28 kDa in media conditioned by regenerating fish optic nerves. The level of this polypeptide increased after injury by approximately 35%. Apo-A-I was isolated by gel-permeation chromatography from delipidated high-density lipoproteins (HDL) that had been obtained from carp plasma by sequential ultracentrifugation. Further identification of the purified protein as apo-A-I was based on its molecular mass (28 kDa) as determined by gel electrophoresis, amino acid composition, and microheterogeneity studies. The isolated protein was further analyzed by immunoblots of two-dimensional gels and was found to contain six isoforms. Western blot analysis using antibodies directed against the isolated plasma protein showed that the 28-kDa polypeptide in the preparation of soluble substances derived from the fish optic nerves (conditioned media, CM) cross-reacted immunologically with the isolated fish plasma apo-A-I. Immunoblots of two-dimensional gels revealed the presence of three apo-A-I isoforms in the CM of regenerating fish optic nerves (pIs: 6.49, 6.64, and 6.73). At least some of the apo-A-I found in the CM is derived from the nerve, as was shown by pulse labeling with [35S]methionine, followed by immunoprecipitation. The apo-A-I immunoactive polypeptides in the CM of the fish optic nerve were found in high molecular-weight, putative HDL-like particles. Immunocytochemical staining revealed that apo-A-I immunoreactive sites were present in the fish optic nerves. Higher labeling was found in injured nerves (between the site of injury and the brain) than in non-injured nerves. The accumulation of apo-A-I in nerves that are capable of regenerating may be similar to that of apo-E in sciatic nerves of mammals (a regenerative system); in contrast, although its synthesis is increased, apo-A-I does not accumulate in avian optic nerves nor does apo-E in rat optic nerves (two nonregenerative systems).

Animals↗
PubMed1988

Group formation and ideology. Text and context.

The relationship between the phenomenon of 'mass formation' (Massenbildung) and the production and circulation of ideologies is examined. The explanation of the said relationship must take into account both the social dimension as well as the intrapsychic structure of the ideological. To achieve this a brief review of Freud's ideas on group psychology and of some definitions of ideology, namely those proposed by Ricoeur, Althusser and Habermas is expounded. In the same way as the understanding of the vicissitudes of identification is crucial to gain insight into 'mass formation', the investigation of the processes of idealization is vital to the understanding of the ideological.

Dominance-Subordination↗
PubMed1987

Induction chemotherapy with cisplatin, bleomycin and methotrexate in advanced head and neck cancer--lack of therapeutic gain.

Seventy patients with stage IV head and neck cancer were treated by two courses of induction chemotherapy followed by surgery plus postoperative irradiation (7) or radical radiotherapy (62). One patient renounced to further treatment after chemotherapy. Each chemotherapy course consisted of methotrexate (40 mg/m2 days 1 and 14), bleomycin (10 mg/m2 days 1, 7 and 14), and cisplatin (50 mg/m2 day 4). Three patients did not complete the two courses of chemotherapy planned due to bad tolerance whereas the rest of the patients tolerated chemotherapy well. 2 CR (3%) and 35 PR (50%) were achieved for an overall response rate to chemotherapy of 53%. 35 (50%) CR were achieved with the whole treatment schedule. The 5-year disease-free survival is 26% for the whole group of patients. The prior response to chemotherapy neither influenced the complete responses to treatment nor the relapse-free survival. The addition of this chemotherapy to conventional treatment was of no value.

Adolescent↗
PubMed1987

Some genetic markers in Catalonia.

A random sample from the Catalonian population was studied for 4 serum polymorphisms (HP, GC, Gm, Km). Gene frequencies agree with those of other South-western European populations. Compared to Castilla the GC system shows a significant difference.

Blood Proteins↗
PubMed1986

Acute modulation of the hypothalamic-pituitary axis by intravenous testosterone in normal women.

Intravenous testosterone was infused for 6 hours in 23 ovulatory women, divided into five groups according to dose, to assess the effects of testosterone on gonadotropin secretion. Serum testosterone increased from 0.24 +/- 0.08 to steady-state levels of 1.63 +/- 0.18 ng/ml in the lowest-dose group (1) and to 42.1 +/- 3.3 ng/ml in the highest-dose group (4). In another group (5), patients were pretreated with testolactone, which prevented the estradiol rise associated with testosterone infusion. All groups except group 1 exhibited significant reductions in the delta maximum responses of luteinizing hormone to gonadotropin-releasing hormone during testosterone infusion compared with pretreatment levels (p less than 0.01). This was also evident for the testolactone group (5). There were no observed changes in serum follicle-stimulating hormone. Luteinizing hormone pulse frequency was decreased (p less than 0.05) with testosterone concentrations of 27.2 +/- 0.77 and 42.1 +/- 3.3 ng/ml (groups 3 and 4), but only in the highest group (4) was there a decrease in pulse amplitude (p less than 0.05). No luteinizing hormone pulse changes were observed with lower concentrations of testosterone. Plasma immunoreactive gonadotropin-releasing hormone levels remained undetectable or low in some of the groups sampled. These data suggest that short-term infusions of testosterone inhibit hypothalamic-pituitary function of normal women when high doses are used, and this effect may be independent of aromatization to estrogen.

Adult↗
PubMed1986

Relationship of plasma growth hormone-releasing hormone levels to pubertal changes.

Basal plasma GH-releasing hormone (GHRH) concentrations were measured by RIA in 180 normal subjects (93 boys and 87 girls between the ages of 8 and 18 yr). Every subject was in good health and between -2 and +2 SD for height. Fourteen boys with delayed puberty also were studied. Plasma GHRH concentrations were higher during puberty than before it. At midpuberty, the mean GHRH levels in girls was 159.1 +/- 28.5 (+/- SEM) pg/ml, approximately 5-fold higher than the level in prepubertal girls (30.3 +/- 4.3 pg/ml). The mean plasma GHRH in midpubertal boys (101.4 +/- 11.5 pg/ml) was approximately 2-fold higher than the level in prepubertal boys (48.1 +/- 5.2 pg/ml). The GHRH levels in boys with delayed puberty more closely resembled those in boys at a similar pubertal stage than those in boys of similar chronological age. The dramatic rise in plasma GHRH levels during puberty suggests a role for this peptide in the adolescent growth spurt. Moreover, these data indicate that GHRH levels during adolescence may be a marker of the patient's pubertal development.

Adolescent↗
PubMed1985

Cholecystoduodenal fistula.

An elderly woman with a history of cholelithiasis was seen for right upper quadrant pain and jaundice. During her evaluation, she was found to have extensive choledocholithiasis and a cholecystoduodenal fistula. Successful management was accomplished with cholecystectomy, removal of the common bile duct stones, and by creating a choledochoduodenostomy where the fistula had been present.

Aged↗
PubMed1981

Management of Hodgkin's disease in a patient with sickle cell anemia.

A right periauricular swelling developed in a 21-year-old woman with sickle cell anemia. The mass was removed and revealed Hodgkin's disease of the lymphocyte predominance type. While preparing the patient for a staging laparotomy, an allo-anti-Kell and an allo-antic-C were identified in the patient's sera. The patient's direct antiglobulin test was positive and an auto-anti-e was eluted from the patient's erythrocytes. The patient was treated with nine courses of MOPP therapy given over a nine-month period. The clinical and therapeutic implications for the management of patients with sickle cell anemia and lymphoproliferative disorders are discussed.

Adult↗
PubMed1980

A cross-over study comparing the kinetics of Tc-99m-labeled diisopropyl and p-butyl IDA analogs in patients.

Tc-99m-diisopropyl-IDA (DISIDA) and Tc-99m-p-butyl-IDA (BIDA) were compared in each of 33 patients who had serum bilirubins ranging from normal to 23.5 mg/dl. DISIDA exhibited quantitatively a higher liver uptake and faster rate of washout at all levels of bilirubinemia. There was a tendency for BIDA to have a slower blood clearance, particularly in hyperbilirubinemias exceeding 5 mg/dl. On visual comparison of the images, BIDA failed to identify the gallbladder in three icteric patients and dilated biliary tracts in two others.

Adult↗
PubMed1980

A crossover study comparing the kinetics of Tc-99m-labeled diethyl- and diisopropyl-IDA.

Tc-99m-diisopropyl-IDA (DISIDA) and Tc-99m-diethyl-IDA (DE-IDA) were compared in each of 44 patients who had serum bilirubin levels ranging from normal to 50 mg/dl. Quantitative and qualitative analysis showed a significantly higher liver uptake relative to background for DISIDA. No significant differences between DISIDA and DE-IDA were found in the blood retention and rate of liver washout. Clinically, the diagnostic information received from both radiopharmaceuticals was essentially the same.

Adult↗
PubMed1980

On the release of catecholamines and dopamine-beta-hydroxylase evoked by ouabain in the perfused cat adrenal gland.

1 Secretion of catecholamines (CA) and dopamine-beta-hydroxylase (DBH) activity from the retrogradely perfused cat adrenal gland was studied following ouabain infusion. Perfusion with ouabain (10(-4) M) for 10 min caused a gradual release of CA in the effluent which reached its peak 30 min after the ouabain pulse, and was maintained constant for at least 1 h. The effect of ouabain seemed to be irreversible. 2 Mecamylamine, while blocking the CA secretory effects of acetylcholine (ACh) perfusion, did not affect the secretion of CA evoked by ouabain. In denervated adrenal glands, ouabain-induced CA secretion was similar to that in the contralateral, innervated gland. However, physostigmine perfusion potentiated the CA secretory effects of ouabain. 3 The release of CA evoked by ouabain was accompanied by a proportional release of DBH activity. The time course of appearance of DBH activity followed the pattern of CA release. 4 The CA and DBH outputs in response to a pulse of ouabain were suppressed in the absence of calcium. Calcium reintroduction to a calcium-free perfused, ouabain-treated gland not only restored but greatly potentiated the release of CA and DBH. The amplitude of the secretory response to calcium reintroduction in ouabain-treated glands was proportional to the extracellular calcium concentration, and was antagonized by an external sodium-deficient medium. 5 These data demonstrate that ouabain releases CA from the perfused cat adrenal gland by a calcium-dependent exocytotic mechanism. The secretory effect of ouabain is not secondary to the release of ACh from cholinergic nerve terminals present in the adrenal gland, but due to a direct action on the chromaffin cell itself. In addition, the results suggest that this action is exerted through redistribution of monovalent cations secondary to the inhibition by the glycoside of the sodium pump. Such monovalent cation redistribution may cause a rise of intracellular ionized calcium levels through the activation of an internal sodium-dependent calcium influx system probably located in the chromaffin cell membrane.

Adrenal Glands↗
PubMed1979

Differential diagnosis of jaundice by 99mTc-IDA hepatobiliary imaging.

The utility of 99mTc-IDA imaging in the differential diagnosis of jaundice was assessed. Although overall accuracy was 84%, this method is still inferior to the reported efficiency of ultrasonography and CT in making the correct diagnosis. Radionuclide imaging is a good alternative when these other modalities are not available and it functions well in an adjuvant capacity. The diagnostic limitations of 99mTc-dimethyl IDA imaging in cases of moderate to severe jaundice are largely overcome by the use of 99mTc-p-butyl IDA.

Aged↗