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Biomedical subjects

E M Gonzalez

Publications and source records attributed to E M Gonzalez.

At least 19 recordsLinked to original sources
PubMed2003

A superconducting reversible rectifier that controls the motion of magnetic flux quanta.

We fabricated a device that controls the motion of flux quanta in a niobium superconducting film grown on an array of nanoscale triangular pinning potentials. The controllable rectification of the vortex motion is due to the asymmetry of the fabricated magnetic pinning centers. The reversal in the direction of the vortex flow is explained by the interaction between the vortices trapped on the magnetic nanostructures and the interstitial vortices. The applied magnetic field and input current strength can tune both the polarity and magnitude of the rectified vortex flow. Our ratchet system is explained and modeled theoretically, taking the interactions between particles into consideration.

Journal Article↗
PubMed2000

Head and trunk in zebrafish arise via coinhibition of BMP signaling by bozozok and chordino.

Spatial variations in the levels of bone morphogenetic protein (BMP) signaling are a critical determinant of dorsoanterior-ventroposterior pattern in vertebrate embryos. Whereas BMP overexpression abolishes both head and trunk development, known single and double loss-of-function mutations in BMP inhibitors have less dramatic effects. We report that combining mutations in the zebrafish genes bozozok and chordino causes a synergistic loss of head and trunk, whereas most cells express ventro-posterior markers and develop into a tail. Genetic inactivation of BMP signaling fully suppresses these defects. Thus, a remarkably simple genetic mechanism, involving a coinhibition of BMP function by the partially overlapping bozozok and chordino pathways is used to specify vertebrate head and trunk.

Animals↗
PubMed1999

Maternal and zygotic activity of the zebrafish ogon locus antagonizes BMP signaling.

The dorsal-ventral axis of vertebrate embryos is thought to be specified by a gradient of bone morphogenetic protein (BMP) activity, which, in part, arises through the interaction of dorsally expressed antagonists Chordin and Noggin with the ventralizing BMPs. The zebrafish mercedes(tm305), ogon(m60), and short tail(b180) mutations produce ventralized phenotypes, including expanded bmp2b/4 expression domains. We find that the three mutations are allelic and that the locus they define, renamed ogon (ogo), maps to linkage group 25. The ogo(m60) and ogo(b180) mutations are deficiencies and thus represent null alleles, whereas the ENU-induced allele ogo(tm305) retains partial function. Aspects of the ogo(m60) and ogo(tm305) mutant phenotypes are fully suppressed by overexpression of BMP antagonists. Moreover, swirl(tc300), a null mutation in bmp2b, is epistatic to ogo(m60) mutation, providing further evidence that ogo normally functions in a BMP-dependent manner. Embryonic patterning is highly sensitive to maternal and zygotic ogo gene dosage, especially when the level of zygotic chordin activity is also reduced. However, elimination of the zygotic activity of both genes does not result in a completely ventralized embryo. Thus, while ogo and chordin are required to limit activity of BMPs, additional mechanisms must exist to block these ventralizing signals. We have ruled out zebrafish noggin homologues as candidates for the ogo gene, including a newly identified gene, nog1, which is specifically expressed in the gastrula organizer. The results suggest that ogo encodes an as yet unidentified dorsalizing factor that mediates dorsoventral patterning by directly or indirectly antagonizing BMP activity.

Amino Acid Sequence↗
PubMed1996

Experimental corneal neovascularisation using sucralfate and basic fibroblast growth factor.

PURPOSE: To develop a non-inflammatory model of both acute and chronic angiogenesis in the rabbit cornea using a known directly angiogenic cytokine. METHODS: Pellets made of the slow-release polymer Hydron (polyhydroxyethylmethacrylate) and containing sucralfate and/or basic fibroblast growth factor (basic-FGF) were implanted into rabbit corneas. The neovascular response to the implantation of pellets containing basic-FGF alone, sucralfate alone or a titration of basic-FGF in the presence of a constant amount of sucralfate was measured. The role of inflammation in the neovascular response was also investigated. RESULTS: The addition of sucralfate to the pellets led to the sustained release of basic-FGF resulting in a predictable and aggressive neovascular response with a low dose of basic-FGF that by itself was unable to elicit neovascularisation. At a dose of 500 ng per pellet, approximately one-third of the surface area of the cornea was vascularised within eight days of implantation. Minimal or no vascularisation occurred with the same dose of basic-FGF without sucralfate. While this dose of basic-FGF induced corneal oedema, only minimal inflammation was observed and the response was unaffected by ionising radiation. A less aggressive though still robust neovascular response with no or only minimal oedema was observed when the dose was lowered to 50 ng of basic-FGF per pellet. Some induced vessels persisted for more than three months. CONCLUSION: This is an inexpensive in vivo model of angiogenesis with the advantages of the neovascularisation being aggressive, predictable, persistent, unassociated with an obvious inflammatory response and induced by the sustained release of an agent known to have a direct stimulatory action on endothelial cells.

Acute Disease↗
PubMed1991

Angiostatic steroids potentiated by sulfated cyclodextrins inhibit corneal neovascularization.

It is known that hydrocortisone can be converted to a potent angiogenesis inhibitor by coadministration with heparin or with a sulfated cyclodextrin. The activity of tetrahydrocortisol-S, a purely angiostatic corticosteroid, can be potentiated by beta-cyclodextrin tetradecasulfate as shown in this study. This drug "pair" and other pairs of corticosteroids and beta-cyclodextrin tetradecasulfate can be applied topically to inhibit corneal neovascularization. Endotoxin-induced corneal neovascularization in rabbits was treated with beta-cyclodextrin tetradecasulfate coadministered with either: hydrocortisone, tetrahydrocortisol-S, or 6-alpha-fluoro-17,21-dihydroxy-16-beta-methyl-pregna-4,9(11),diene,3, 20-dione. When optimal ratios of steroid and cyclodextrin were used, neovascularization was reduced to 13%, 26%, and 28% of untreated controls for the three steroids, respectively. Hydrocortisone-cyclodextrin drug pairs suppressed virtually all inflammatory cell infiltration (induced by endotoxin), whereas tetrahydrocortisol-cyclodextrin pairs only partially reduced inflammation. These results demonstrate that corneal neovascularization and corneal inflammation are separable processes and that the neovascularization may be treated specifically using angiostatic steroids without inflammatory activity.

Administration, Topical↗
PubMed1990

Successful treatment with ketoconazole of Cushing's syndrome in pregnancy.

Patients with Cushing's syndrome rarely become pregnant. This is a high risk situation both for the fetus and the mother, if untreated. We report a patient with Cushing's syndrome due to adrenocortical adenoma who became pregnant and was successfully treated with ketoconazole during the last period of pregnancy.

Adenoma↗
PubMed1981

Extented esophago-gastretomy as surgical treatment for carcinoma of the cardia.

With the object of designing a feasible and more radical surgical intervention for the treatment of carcinoma of the gastric cardia and improving the long term survival of these patients, a procedure was described which entails total esophagogastrectomy and resection of the distal pancreas, spleen and regional lymphnodes. The esophagus was mobilized via the diaphragmatic hiatus without thoracotomy. Intestinal continuity, installed isoperistaltically was restituted in the same operation using a segment of transverse and descending colon transferred to the left lateral cervical aspect by way of the posterior mediastinum. The procedure was used in four patients and mortality and serious complications were nil.

Adenocarcinoma↗
PubMed1981

Treatment of splenic artery aneurysm after distal splenorenal shunt. A case report.

A patient with splenic artery aneurysm which developed after creation of selective distal spleno-renal shunt for hepatic cirrhosis and portal hypertension was presented. Three months after operation, an aneurysm of the splenic artery with a diameter of about 20 mm was detected. This aneurysm reached 4 cm three months later, and a resection was carried out. An arterial continuity was established by means of end-to-end anastomosis of the sectioned arterial ends. Because the flow through the splenic artery was about 60% of the total flow of the selective distal spleno-renal shunt, it is important to maintain continuity in order to avoid thrombosis of the shunt.

Adult↗
PubMed1979

Selective coronary-caval shunt using internal jugular autograft, in the treatment of portal hypertension.

The selective coronary-caval shunt is considered to be one of the better procedures in the surgical treatment of portal hypertension. We have altered the previously described technique by using an internal jugular vein grafting which possesses some advantages. We have performed this shunt utilizing an internal jugular vein autograft in eight patients, who had at least one major hemorrhage from esophageal varices three to twelve months before operation. There were no postoperative deaths. All four patients are still alive three months to six years after shunting without bleeding episodes. In the X-ray and endoscopic studies the esophagogastric varices were noted to be markedly smaller in size than they were before shunting.

Coronary Vessels↗
PubMed1979

DC polarography of cephradine and its application to capsules.

A polarographic method has been developed for the quantitative analysis of cephradine and its dosage forms. Direct determinations on capsules are carried out; excipients and coloring matter do not interfere in the determination. The electroactive product is formed by acidic hydrolysis with 5.0N HCl and heating at 80 degrees C for 60 min. Two polarographic waves are obtained: I = -0.46 V and II = -0.78 v vs. SCE. Both reduction waves are diffusion controlled. Wave I is preferred for analytical purposes. The precise chemical identity of the electroactive product has not been determined, but UV spectral data and the TLC Rf value are reported. A linear relation is established for levels of cephradine between 10(-2) and 10(-5)M in 5.0N HCl.

Capsules↗
PubMed1978

Interposition left gastric-caval shunt using internal jugular vein autograft in the treatment of portal hypertension.

The selective left gastric-caval shunt is, in theory, one of the better procedures in the surgical treatment of portal hypertension. We have performed a modification of the previously described technique utilizing an internal jugular vein autograft in 4 patients who had had more than one major haemorrhage from oesophageal varices 3-12 months before operation. There were no post-operative deaths. All 4 patients are still alive 3 months to 4 years after shunting, with no episodes of bleeding. On radiological and endoscopic follow-up, the oesophagogastric varices were noted to be markedly smaller in size than before shunting.

Humans↗
PubMed1978

Polarographic analysis of cephalexin.

Cephalexin was found to be polarographically reducible after hydrolysis in an acidic medium, producing two polarographic waves. Both waves were diffusion controlled. The concentration-diffusion plot method was used for the analysis of cephalexin in capsules.

Cephalexin↗
PubMed1970

Modification of nucleic acid synthesis in regenerating liver by azathioprine.

The effect of azathioprine at 40 mg. per kilogram per day (LD25 at four days) was studied in rats following excision of two thirds of the liver. 1. The restoration of liver mass after four days was unchanged. 2. The rate of DNA synthesis was inhibited by a factor of 100 on the first day. DNA concentration decreased 24 percent by two days and 38 percent by four days in comparison with nontreated rats. 3. The rate of RNA synthesis was at first depressed, then accelerated. RNA concentrations were normal at four days. 4. The ratio of RNA to DNA was increased 59 percent at four days. 5. Hepatic regeneration was chiefly by cellular hypertrophy rather than by hyperplasia.

Animals↗