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Biomedical subjects

R Lopez

Publications and source records attributed to R Lopez.

At least 199 records · Page 11Linked to original sources
PubMed1979

Value of electrocardiogram in predicting and estimating infarct size in man.

The value of the electrocardiogram in assessing infarct size was studied using serial estimates of the MB isomer of creatine kinase (CK MB) in plasma, serial 35 lead praecordial maps in 28 patients with anterior myocardial infarction, and serial 12 lead electrocardiograms in 17 patients with inferior myocardial infarction. In patients with anterior infarcts, sigma ST, sigma R, sigma Q, sigma R/(Q+S), and the number of sites with ST elevation more than 2 mm or with QS waves, were obtained from each map. Correlation between both maximum sigma Q and maximum sigma ST with cumulative CK MB was highly significant. There was also a significant correlation between sigma R and sigma R/(Q+S) with cumulative CK MB. There was no significant correlation between maximum number of sites with ST elevation or with Q or QS waves and cumulative CK MB. Maximum sigma ST and number of sites with ST elevation predicted maximum sigma Q and number of sites with QS or Q waves at a time when infarction was not complete. In patients with inferior infarcts, there was a significant correlation between maximum sigma Q and maximum sigma ST in leads II, III, and a VF, and cumulative CK MB. This study shows that all the waves in the electrocardiogram are useful in assessing infarct size. The fact that maximum sigma ST predicts final sigma Q may be used to assess the efficacy of interventions designed to salvage ischaemic myocardium.

Aged↗
PubMed1979

Problems in resection of chest wall sarcomas.

To illustrate the problems of reconstruction in major chest wall resection, five patients with a variety of soft tissue tumors of the chest wall, located at different sites, are presented. Patients, who underwent a lateral or posterolateral chest wall resection required removal of two to five ribs sequentially as well as the adjacent soft tissue. Those who underwent an anterior chest wall resection required resection of the manubrium or the body of sternum as well as of adjacent costal cartilages. To prevent instability of the chest, herniation, and to minimize flailing, the chest defect was bridged with the use of Marlex mesh. Whenever possible, the omentum was brought into the chest cavity to increase the vascularity of the reconstruction. Since, in most instances, the tumors involved the skin because of previous damage from radiation therapy, extensive skin coverage was planned well in advance of resection. Pedicle skin flaps or rotation flaps were used to cover the skin defect. Ventilatory support by volume respirator, was required for three to four days. In all patients, the chest wall was completeley stable after three to six weeks.

Adolescent↗
PubMed1978

Mesenteric fibromatosis in Gardner's syndrome.

Two patients with mesenteric fibromatosis in Gardner's syndrome were treated by us. These tumors are slow-growing and may remain quiescent for long periods. Review of similar cases in the literature discloses that less than half of these tumors have been removed, pointing to the difficulty of their resection. Dissection of the infraduodenal portion of superior mesenteric vessels may help define whether these tumors are resectable. Radiation therapy or treatment with antiestrogens may be helpful in the treatment of unresectable tumors.

Adult↗
PubMed1978

The effect of mental arithmetic on blood pressure variability and baroreflex sensitivity in man.

1. Baroreflex sensitivity was tested in three normal, three borderline and one hypertensive subject before and during mental arithmetic, the prolongation of pulse interval caused by a provoked rise in blood pressure being used as a measure of baroreflex sensitivity. 2. Baroreflex sensitivity was significantly decreased during mental arithmetic. 3. During mental arithmetic the arterial pressure fluctuated markedly. 4. These findings suggest that in man, as well as animals, the defence of alerting reaction depresses baroreflex control and thus contributes to the rise in blood pressure seen at this time.

Blood Pressure↗
PubMed1978

Riboflavin deficiency in women taking oral contraceptive agents.

The effect of oral contraceptive agents (OCA) on riboflavin nutritional status of women of child-bearing age in a low socioeconomic population was studied. For a control group, 100 women in the same age and socioeconomic group using alternate forms of contraception were selected. Riboflavin deficiency was determined by measuring erythrocyte glutathione reductase activity, a reliable index of the deficiency. None of the women was on vitamin supplements or had clinical conditions effecting dietary intake or utilization. Eleven of 100 women in the control group had biochemical evidence of deficiency. This compared to 24 of 56 OCA users who were deficient. The frequency of deficiency increased among those on OCA for longer periods of time. Thirteen of 17 OCA users for 3 years or more, compared to 11 of 39 users under 3 years were deficient. There were no discernable dietary differences between the groups. These studies demonstrate that riboflavin deficiency is a problem of women in the lower socioeconomic level in the child-bearing age. The use of OCA aggravates the prevalence of deficiency.

Adolescent↗
PubMed1978

Comparison of regional versus systemic chemotherapy with adriamycin.

TO ACHIEVE THE HIGH DRUG CONCENTRATIONS IN A TARGET TISSUE (TUMOR) WITH MINIMAL DRUG LEVELS IN ORGANS NOT INVOLVED BY CANCER, THEREBY AVOIDING SERIOUS SYSTEMIC SIDE EFFECTS, THREE METHODS OF ADRIAMYCIN ADMINISTRATION: 1) Isolation perfusion, 2) Intra-arterial infusion, and 3) Intravenous infusion were studied in 22 dogs. Latter two methods were studied in several patients with soft tissue sarcoma of the extremities. Isolation perfusion of the hind extremity was done through the femoral vessels; intra-arterial and intravenous infusions were done through the femoral artery and cephalic vein, respectively. Adriamycin levels in tissues of the hind extremity and blood were determined. The highest Adriamycin levels in tissues could safely be achieved by isolation perfusion. Drug concentrations in regional tissues were not significantly different after intra-arterial infusion as compared to those after intravenous infusion. Much of the drug went into systemic circulation after intra-arterial infusion and almost none after isolation perfusion. Hematologic and histologic evidence of lethal systemic toxicity was noted only in dogs receiving Adriamycin by infusions. Edema, patchy muscle necrosis, hemorrhages, and skin ulcerations were observed in the perfused extremities only. In human studies, drug levels in blood were comparable to those in animal study when Adriamycin was administered by the latter two methods.

Animals↗
PubMed1978

Transfection of Streptococcus pneumoniae with bacteriophage DNA.

It was possible to transfect Streptococcus pneumoniae with DNA obtained from a newly isolated bacteriophage, diplophage-4 (Dp-4). Optimal frequency of transfection (0.9%) required the use of a nuclease-defective mutant; with wild-type bacteria, the transfection frequency was about 100-fold lower. Transfection requires physiological conditions that appear to be similar to the competent state needed for genetic transformation (A. Tomasz, J. Bacteriol. 91:1050--1061, 1966).

Bacteriophages↗
PubMed1978

Comparison of two procedures for freezing semen from cocks of high and low fertility with frozen semen.

Semen samples from groups of males chosen for high or low freezability of semen were frozen by two different methods, one using glycerol as the cryoprotectant and the other using DMSO. Fertilizing capacity was highest from semen collected from males of the high group and frozen in the presence of DMSO. Neither semen source nor method of freezing had any influence on the hatch of fertile eggs.

Animals↗
PubMed1978

Estramustine phosphate in the treatment of advanced malignant melanoma.

Twenty-six patients (14 men and 12 women) with histologically proven advanced malignant melanoma, who previously had not responded to DTIC, methyl-CCNU, and procarbazine, received estramustine phosphate (estracyt) (15 mg/m2) in daily divided doses. All patients had measurable disease. One patient developed a complete remission and one patient had improvement in liver function without measurable regression in the tumor. In three other patients (11%), the disease remained static for a period of 3--5 months. The mean survival time from the beginning of therapy was 16.8 months for the patients with a response or static disease and 2.18 months for those who had no response. Gastrointestinal toxicity was minimal; no hematologic toxicity was observed. It appears that estramustine phosphate used as a single agent for treating advanced malignant melanoma after patients failed to respond to DTIC and to the combination of methyl-CCNU and procarbazine has a poor response rate.

Adult↗
PubMed1977

Light (phototherapy)--induced riboflavin deficiency in the neonate.

Phototherapy with blue light decomposes riboflavin, which has a maximum absorption at 450 nm. A study was designed to determine whether riboflavin deficiency developed in neonates who received phototherapy for moderate hyperbilirubinemia. Twenty-one infants with normal erythrocyte glucose-6-phosphate dehydrogenase activity were investigated. Five infants with moderate hyperbilirubinemia who did not require phototherapy served as the controls. Riboflavin deficiency was determined from the degree of saturation of erythrocyte glutathione reductase, a method shown to reflect riboflavin nutritional status in the neonate. Sixteen of 21 infants who were exposed to phototherapy developed riboflavin deficiency; all who had phototherapy for 49 hours or more developed the deficiency. That the concentration of serum bilirubin or the duration of hyperbilirubinemia was not a factor is supported by the fact that none of the controls became deficient. This observation may have important metabolic and clinical consequences for the neonate.

Female↗
PubMed1977

Role of the pneumococcal autolysin (murein hydrolase) in the release of progeny bacteriophage and in the bacteriophage-induced lysis of the host cells.

The pneumococcal bacteriophage Dp-1 seems to require the activity of the N-acetylmuramic acid-L-alanine amidase of the host bacterium for the liberation of phage progeny into the medium. This conclusion is based on a series of observations indicating that the exit of progeny phage particles is prevented by conditions that specifically inhibit the activity of the pneumococcal autolysin. These inhibitory conditions are as follows: (i) growth of the bacteria on ethanolamine-containing medium; (ii) growth of the cells at pH values that inhibit penicillin-induced lysis of pneumococcal cultures and lysis in the stationary phase of growth; (iii) addition of trypsin or the autolysin-inhibitory pneumococcal Forssman antigen (lipoteichoric acid) to the growth medium before lysis; (iv) infection of an autolysin-defective pneumococcal mutant at a multiplicity of infection less than 10 (treatment of such infected mutant bacteria with wild-type autolysin from without can liberate the entrapped progeny phage particles); (v) release of phage particles and culture lysis can also be inhibited by the addition of chloramphenicol to infected cultures just before the time at which lysis would normally occur. Bacteria infected with Dp-1 under conditions nonpermissive for culture lysis and phage release secrete into the growth medium a substantial portion of their cellular Forssman antigen in the form of a macromolecular complex that has autolysin-inhibitory activity. We suggest that a phage product may trigger the bacterial autolysin by a mechanism similar to that operating during treatment of pneumococci with penicillin (Tomasz and Waks, 1975).

Amidohydrolases↗
PubMed1977

Properties of "diplophage": a lipid-containing bacteriophage.

We describe the purification and properties of Dp-1, a bacteriophage isolated from Diplococcus pneumoniae. The phage was sensitive to the organic solvents deoxycholate and Sarkosyl, and its infectivity was reduced by treatment with phospholipase C. Electron microscopy indicated the presence of a double-layered coat around the phage particles. Purified phage preparations contained lipid amounting to about 8.5% of the dry weight of the phage, and thin-layer chromatography resolved the lipids into four components. The phage had a buoyant density in CsCl of 1.47 g/cm3, and a sedimentation constant in 0.1 M NaCl of 313S. Analysis in acrylamide gel electrophoresis indicated the presence of three major proteins. Dp-1 DNA shows a density of 1.681 g/cm3. Neutralizing antisera against the phage have a low potency (K less than 120/min).

Adsorption↗