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Biomedical subjects

A Montoya

Publications and source records attributed to A Montoya.

At least 73 records · Page 4Linked to original sources
PubMed1985

Prospective double-blind trial of two different doses of mefloquine plus pyrimethamine-sulfadoxine compared with pyrimethamine-sulfadoxine alone in the treatment of falciparum malaria.

This double-blind study is based on the treatment of 75 adult male patients suffering from Plasmodium falciparum malaria in Medellín, Colombia, a city in which there is no malaria transmission. The patients, who came from regions with high resistance to antimalarials, were divided into three groups receiving single-dose treatment as follows: a combination of 280 mg mefloquine, 800 mg sulfadoxine and 40 mg pyrimethamine; a combination of 420 mg mefloquine, 1200 mg sulfadoxine and 60 mg pyrimethamine; and a combination of 1500 mg sulfadoxine and 75 mg pyrimethamine. After treatment, follow-up examination was performed daily for I week and then weekly for another 3 weeks. The cure rate in the mefloquine groups (within the study period of 28 days) was 100%, and in the third group 75%. Normal blood levels of the administered drugs were found in 6 patients of the third group who were not cured; they were subsequently cured with a single dose of 1000 mg of mefloquine. Drug tolerance was good and no toxic effects were demonstrated in blood and urine examinations. While the doses in the drug combinations (containing mefloquine) gave very good results, we would recommend a slightly higher dose combination of mefloquine with sulfadoxine-pyrimethamine for the treatment of falciparum malaria in areas with a high prevalence of chloroquine resistance.

Adolescent↗
PubMed1985

Urgent surgery for ventricular septal rupture complicating acute myocardial infarction.

Medical treatment of postinfarction ventricular septal rupture carries a high mortality. Delayed surgery can be done with good results but many patients die awaiting operation. In 1978 we decided that all such patients presenting to us should undergo urgent cardiac catheterization and surgery. Since then we have seen 22 such patients. Two decided against surgery and died in the hospital. Twenty agreed to surgery; in 15 of these an intra-aortic balloon pump was inserted before catheterization and in another four at the time of operation. Catheterization was performed without complication, and surgery was performed within 2 days of septal rupture in all 20 patients. Twelve patients (60%) survived hospitalization. Three patients died of pump failure shortly after surgery; five died after a second operation for free wall rupture (n = 2) or persistent or recurrent septal defect (n = 3). Two other patients survived reoperation. Survivors were significantly younger than nonsurvivors and had a higher cardiac index and a lower shunt ratio. At a mean follow-up of 47.9 months, there has been one late noncardiac death. Eleven patients survive, all in class I or II. We conclude that in patients with septal rupture urgent surgery results in improved near-term survival compared with known survival rates in medically treated patients. Early recurrent rupture is common and often disastrous and requires refinement in operative technique. Age, cardiac index, and shunt volume are related to surgical outcome. Hospital survivors do very well on a long-term basis. We recommend continuation of this aggressive approach.

Age Factors↗
PubMed1984

Nucleotide sequence of the tms genes of the pTiA6NC octopine Ti plasmid: two gene products involved in plant tumorigenesis.

The nucleotide sequence of the tumor morphology locus, tms, from pTiA6NC has been determined. The sequence analysis indicates that each of two polyadenylylated transcripts encoded by this locus contains an open reading frame; the predicted transcript 1 gene product has a molecular size of 83,769 daltons, and the predicted transcript 2 gene product, of 49,588 daltons. The precise start and stop positions of the transcript 2 RNA have been mapped with S1 nuclease. Several insertion mutations have been constructed. One of these localizes the transcript 2 promoter within the 72 base pairs 5' to transcription initiation. Significant homology was observed between the protein encoded by transcript 1 and the adenine binding region of p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens, suggesting that the transcript 1 protein binds adenine either as substrate or cofactor.

Amino Acid Sequence↗
PubMed1984

Physical and functional map of an Agrobacterium tumefaciens tumor-inducing plasmid that confers a narrow host range.

Agrobacterium tumefaciens Ag162 induces crown gall disease on an unusually narrow range of host plants. The 231-kilobase Ti plasmid which has been shown to determine host range, was subcloned into the vector pVCK102. By comparing overlaps of cloned insets, maps were constructed for the restriction endonucleases SalI, XhoI, EcoRI, and KpnI. Plasmid incompatibility, octopine catabolism, and at least six virulence genes were localized. Plasmid incompatibility between pTiAg162 and the wide host range plasmid pTiA6 consists of two components: mutual incompatibility and the apparent ability of pTiA6 to block RK2 replication if the pTiAg162 incompatibility locus is linked to the vector pVK102. The octopine catabolism locus maps within the 30 kilobases of DNA separating the two T-DNA regions of pTiAg162. Complementation of avirulent vir mutants of pTiA6 with clones of pTiAg162 DNA did not confer the host range of pTiAg162 but rather restored the wide host range of pTiA6. One potentially important difference between pTiA6 and pTiAg162 is that pTiAg162 T-DNA regions are widely separated.

Arginine↗
PubMed1984

Nucleotide sequence and transcript mapping of the tmr gene of the pTiA6NC octopine Ti-plasmid: a bacterial gene involved in plant tumorigenesis.

The nucleotide sequence of a tumor morphology gene, tmr, from the Agrobacterium tumefaciens Ti-plasmid, pTiA6NC, and its flanking 5' region was determined by M13 "dideoxy" procedures. The DNA sequence reveals an open reading frame capable of encoding a 240 amino acid protein. We have identified the polyadenylated transcript initiation and termination sits by S1 nuclease mapping. The extent of the sequence required for transcription 5' to the start of transcription has been delimited by two transposon insertions. The first of these maps at -- 121 with respect to transcription initiation and results in the wild-type phenotype, the second insertion maps at about -85 and results in a tmr phenotype.

Arginine↗
PubMed1983

Management of left ventricular rupture complicating myocardial infarction.

Rupture of the left ventricle secondary to myocardial infarction may occur more often than is suspected. More time than anticipated may be available between rupture and catastrophic deterioration. Hemodynamic stabilization, diagnostic studies, and surgical treatment can be successfully undertaken. Four patients have been successfully treated in our institution. Rupture occurred from 1 to 14 days after infarction. Persistent chest pain was present in all. All were hemodynamically unstable and all stabilized with counterpulsation. One patient was in cardiogenic shock, two had a cardiac arrest, and one presented with cardiac tamponade requiring two emergency pericardiocenteses. Coronary arteriography was done in all four patients. Surgical management consisted of infarctectomy and repair of the ventricular rupture. Additionally, a single aortacoronary bypass graft was needed in two patients and repair of a ventricular septal rupture was necessary in a third. There was no operative mortality. One patient drowned 1 year later. We conclude that successful surgical management requires (1) suspicion of ventricular rupture, (2) hemodynamic stabilization by counterpulsation, (3) coronary arteriography, and (4) combined infarctectomy and repair with revascularization.

Aged↗
PubMed1982

Acute coronary artery occlusion secondary to blunt chest trauma.

Two patients suffered an acute transmural MI due to complete occlusion of the proximal LAD after blunt chest trauma. One developed a rupture of the ventricular septum with a ventricular aneurysm and the other an acute ventricular aneurysm, both accompanied by congestive heart failure. Neither had a history of ischemic heart disease; both had normal right and circumflex coronary arteries by arteriography. An intimal tear or subintimal hemorrhage with luminal thrombosis, or both, are the suggested mechanisms of coronary artery occlusion. Both patients were operated upon successfully. Patient 1 underwent closure of the VSD and resection of the ventricular aneurysm. The LAD had returned to normal and required no aortocoronary bypass graft. Patient 2 underwent arteriotomy of the LAD with Fogarty catheter embolectomy and aortocoronary bypass graft, combined with resection of the ventricular aneurysm. We recommend that patients who suffer blunt chest trauma and show ECG changes should undergo cardiac catheterization and coronary arteriography, followed by the pertinent treatment.

Accidents, Traffic↗
PubMed1981

Constrictive pericarditis following cardiac surgery.

Five patients with constriction secondary to pericarditis or membrane formation following cardiac surgical procedures are reported. In 4 of the 5 patients, a postpericardiotomy syndrome developed after the original procedure. Constriction occurred from ten weeks to almost 6 years after the cardiac operation. Clinicians should watch carefully for the delayed onset of constriction in patients with a postpericardiotomy syndrome after cardiac operation.

Cardiac Surgical Procedures↗
PubMed1981

Management of postoperative heparin rebound following cardiopulmonary bypass.

Postoperative heparin rebound was investigated in 50 adult patients undergoing cardiopulmonary bypass with the use of the Hepcon heparin analyzer. Prior to bypass each patient received 2 mg/kg of heparin. During bypass, the activated clotting time (ACT) was utilized to assess the need for additional heparin to maintain the value between 300 and 400 seconds. The average amount of heparin given was 160 mg. Once cardiopulmonary bypass was terminated the Hepcon unit was employed to determine the actual amount of active circulating heparin and to calculate the dose of protamine sulfate. The average amount of protamine administered intraoperatively was 200 mg. The overall mean ratio of protamine-to-heparin was 1.25 : 1. Once hemostasis was achieved, no circulating heparin was measured with the Hepcon unit, and the ACT value had returned to its baseline, the incisions were closed and the patients were transferred to the intensive care unit. One hour later a blood sample was obtained and analyzed by the Hepcon unit for any heparin rebound. We found that 26 patients (52%) had circulating heparin and required an additional dose of protamine, averaging 70 mg. Drainage from the thoracotomy tubes averaged 400 cc in the first 24 hours, and a mean of 2 units of packed cells was infused. Three patients (6%) did not require any blood transfusions. The use of the Hepcon unit has produced a safe and expedient method of analyzing and neutralizing active circulating heparin in patients following cardiopulmonary bypass. It is a useful adjunct in blood conservation because it reduces excessive postoperative blood loss associated with heparin rebound.

Blood Transfusion↗
PubMed1980

Experience with simultaneous myocardial revascularization and carotid endarterectomy.

Fifty-four patient had coexisting stenosis of the carotid artery (70% or greater) and coronary artery disease. Simultaneous carotid endarterectomy and myocardial revascularization were done in all cases. One permanent postoperative neurologic deficit occurred (1.9%). There were no deaths. Our experience with simultaneous correction of combined carotid and coronary disease leads us to conclude that simultaneous myocardial revascularization and carotid endarterectomy have low mortality and neurologic morbidity rates. The policy at Loyola University Medical Center at this time is to routinely perform simultaneous endarterectomy and myocardial revascularization in all patients with significant coexisting carotid and coronary disease.

Aged↗
PubMed1979

The advantages of open mitral commissurotomy for mitral stenosis.

Mitral commissurotomy is the treatment of choice for mitral stenosis. If this is not feasible, replacement of the valve becomes necessary. Open commissurotomy has been performed at Loyola University Medical Center, Maywood, Ill, in 105 patients since 1970. The mean age was 45 years. The indication for surgery was heart failure in 92 of the cases. Sixty of the patients were in class 3 of the New York Heart Association (NYHA) classification. Eighty-five underwent open mitral commissurotomy alone. This was not feasible in 42 patients scheduled for it who required valvular replacement. Twenty-five patients had a left atrial thrombus. Two patients died, one from aortic dissection and the other from acute infarction in the perioperative period. Ninety-eight patients are NYHA class 1 or 2 at present. Two patients required valvular replacement following the commissurotomy. The low mobidity and mortality with excellent long-term results support our contention that open mitral commissurotomy is the treatment of choice for mitral stenosis.

Adult↗