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Biomedical subjects

R Kauffman

Publications and source records attributed to R Kauffman.

At least 19 recordsLinked to original sources
PubMed2005

Evidence for high-efficiency laser-heated hohlraum performance at 527 nm.

A series of experiments conducted on the HELEN laser system [M. J. Norman, Appl. Opt.4120023497], into thermal x-ray generation from hohlraum targets using 527 nm (2omega) wavelength laser light, has shown that it is possible to exceed radiation temperatures previously thought limited by high levels of superthermal or hot electron production or stimulated backscatter. This Letter questions whether the assumptions traditionally applied to hohlraum design with respect to hot plasma filling and the use of 2omega light are too conservative.

Journal Article↗
PubMed2000

Low serum folate but normal homocysteine levels in patients with atherosclerotic vascular disease and matched healthy controls.

Mild hyperhomocysteinemia has been considered a cardiovascular risk factor. However, recent prospective studies have not demonstrated that hyperhomocysteinemia or the underlying genetic defect on methylentetrahydrofolate reductase is associated with a higher risk of coronary or peripheral artery disease. We compared serum homocysteine, folate, and vitamin B(12) levels of patients with coronary and peripheral vascular disease with those of age- and sex-matched healthy individuals. Subjects taking multivitamins, with diabetes mellitus, or serum creatinine levels over 1.5 mg/dL were excluded from the study. Homocysteine was measured by fluorimetric high-performance liquid chromatography. Serum folate and vitamin B(12) levels were measured by an ion-capture method. We studied 32 patients with peripheral vascular disease (10 female), aged 69.6 +/- 11 y, 24 age- and sex-matched control subjects, 52 patients with coronary artery disease (7 female), aged 59.5 +/- 10.4 y, and 42 age- and sex-matched control subjects. Serum homocysteine levels were 11.7 +/- 7.4 and 9.3 +/- 4.5 micromol/L in vascular patients and in the control counterparts, respectively (not significant). The levels for coronary patients and the control counterparts were 9.0 +/- 3.9 and 8.6 +/- 3.6 micromol/L, respectively (not significant). Folate levels were 4.48 +/- 2.42 and 7.14 +/- 4.04 ng/mL in vascular patients and control subjects, respectively (P < 0.02); the levels in coronary patients and control counterparts were 5.15 +/- 1.9 and 6.59 +/- 2.49 ng/mL, respectively (P < 0.01). No differences in vitamin B(12) or tocopherol levels were observed between patients and control subjects. There were no differences in homocysteine levels, but lower serum folate levels were observed when comparing patients with atherosclerotic vascular disease and healthy control subjects.

Aged↗
PubMed2000

Effects of supplementation with folic acid and antioxidant vitamins on homocysteine levels and LDL oxidation in coronary patients.

Hyperhomocysteinemia is an important cardiovascular risk factor. Serum homocysteine levels are specially dependent on folate nutritional status. In addition, the oxidative modification of low-density lipoproteins (LDLs) in the endothelial microenvironment is a damaging factor that can be modified with fat-soluble antioxidant vitamins. The present study was done to assess the effect of a supplementation of folic acid and antioxidant vitamins on homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease. Twenty-three patients with angiographically proven coronary artery disease were given supplements for 15 d consisting of one capsule twice a day of a multivitamin preparation containing 0.65 mg folic acid, 150 mg alpha-tocopherol, 150 mg ascorbic acid, 12.5 mg beta-carotene, and 0.4 microgram vitamin B12. Serum lipids, vitamin and homocysteine levels, and in vitro LDL oxidation were measured before and after the supplementation period. During the supplementation period, serum folate levels increased from 5.0 +/- 1.5 to 10.8 +/- 3.8 ng/mL (P < 0.001), vitamin B12 increased from 317.4 +/- 130.4 to 334.5 +/- 123.8 pg/mL (P < 0.05), and alpha-tocopherol increased from 8.2 +/- 5.1 to 13.7 +/- 7.9 mg/L (P < 0.001). Serum homocysteine levels decreased from 8.7 +/- 4.3 to 6.3 +/- 2.2 mumol/L (P < 0.001). In vitro LDL oxidation decreased from 2.6 +/- 1.1 to 1.6 +/- 1.1 nmol malondialdehyde/mg protein (P < 0.001). In comparing patients with healthy controls, basal levels of folate were lower in the patients, whereas vitamin B12, alpha-tocopherol, and homocysteine levels were similar. No changes in serum lipid levels or body weight were observed. In conclusion, a short-term supplementation with folic acid and antioxidant vitamins can reduce serum homocysteine levels and in vitro LDL oxidation in patients with coronary artery disease.

Antioxidants↗
PubMed1993

Correlation of gastric emptying at one and two hours following formula feeding.

The acquisition of gastric emptying (GE) data by scintigraphy has become an important component of the evaluation of the pediatric patient for gastroesophageal reflux (GER). Delay of GE can contribute to ongoing gastric distension and hence increase propensity to reflux. Generally, only 1 h GE is determined during scintigraphy. Infants with GER have variable patterns of symptoms: some have spitting, vomiting, choking, and/or apparent life-threatening events in the immediate post-prandial period only, whereas in others symptoms persist until the time of next feeding. It is not clear whether differential rates of GE contribute towards such disparity of symptoms. We performed this prospective study to determine the correlation between GE at 1 h or 2 h, respectively, and for 2 h following a feeding in 27 infants under one year of age, who were referred for evaluation of GER. Continuous scintigraphy was performed for 2 h following a formula feeding. Gastric emptying at 1 h was calculated as percent of original dose emptied by 60 min; GE at 2 h was calculated as percent of isotope remaining in the stomach at 60 min which was emptied by 120 min. The median GE between 0 to 60 min was 36% (95% CI 26.0-42.0) and median GE of the residual formula between 60 to 120 min was 45% (95% CI 34.3-51.3). The correlation coefficient of GE, at 1 h with total GE over 2 h was 0.75 and of GE during the 2nd h with total GE over 2 h was 0.76. We conclude that routine determination of GE for 2 h continuously does not appear to offer clinically significant additional information.

Bottle Feeding↗
PubMed1992

[Assessment of knowledge of cardiopulmonary resuscitation].

The knowledge about standardized CPR of 41 physicians and 30 7th grade medical students was evaluated using a written multiple choice test. Results showed a severe lack of information about CPR in both groups; the test was approved by 39% of physicians and 10% of medical students. Among physicians, the lower achievements were obtained by traumatologists and the best by internists. The basic level of questions were approved by 63% of physicians and 43% of medical students. The principal deficiencies were on pharmacological management and CPR in trauma. It is concluded that education programs on CPR, similar to those given by the American Heart Association, are urgently needed among physicians and medical students.

Cardiopulmonary Resuscitation↗
PubMed1987

Childhood enuresis. A comprehensive treatment program.

Enuresis is a common, often misunderstood, condition that affects millions of children in the United States. For most children with primary enuresis, preventing secondary psychological sequelae associated with guilt and shame is an important consideration in the decision whether or not to treat. Because the spontaneous resolution rate is 15 per cent per year, the older the child, the more important treatment becomes. It is important to distinguish primary from secondary enuresis, as most psychogenically induced enuresis is of secondary nature. A careful history can usually elicit the etiology, as well as the exacerbatory factors in both types of conditions, providing direction for treatment. Treatments include pharmacologic, behavioral, and psychotherapeutic. In some cases, surgical intervention of either a urologic or otolaryngologic nature is indicated. A multidimensional approach is often best, and we have described our program with its success rate. Treating the enuretic child can be frustrating, but is usually quite gratifying for the child, parents, and the clinician.

Behavior Therapy↗
PubMed1986

Morning amnestic effects of triazolam.

The effects of triazolam on immediate and delayed recall were evaluated in a double-blind placebo controlled study in 22 normal volunteers. Subjects were randomized to receive triazolam or a placebo as a single dose administered at bedtime. Immediate and delayed recall are tested using a modified version of the "Williams Word Memory Task" before and at .5, 8, and 14 hours after drug administration. Delayed recall was evaluated at the 14 hour time point for words recalled at the pre drug and 1/2 and 8 hour time points. No significant difference was noted between the triazolam and placebo group with regard to their immediate recall ability at any of the time points. The placebo group demonstrated no decrease in their delayed recall ability during any of the various post drug time points. However, when evaluating delayed recall in the triazolam group, a statistically significant (p less than .05) decrease compared to baseline in their recall ability of words remembered at the .5 and 8 hour time points was noted. This study suggests that triazolam's amnestic effect may extend beyond the duration of its generally accepted hypnotic efficacy. This is consistent with the hypothesis that amnestic potency among the benzodiazepines is related to benzodiazepine receptor binding affinity and lipophilicity.

Adult↗
PubMed1985

A study of adverse reaction algorithms in a drug surveillance program.

To improve agreement among observers, several investigators have recently proposed methods (algorithms) to standardize assessments of causality for presumed adverse drug reactions. We evaluated one such method in the context of an intensive pediatric drug surveillance program. Four observers rated 50 randomly selected case reports drawn from the program, first using only general guidelines and then, several months later, using the strict criteria of the algorithm. Agreement among observers was poor in both study phases. The presence of selected characteristics of adverse events (e.g., major severity) did not improve agreement in either phase of the study. We conclude that routine use of such algorithms in drug surveillance programs is not likely to be of benefit.

Child↗
PubMed1984

Molecular basis for the cardiovascular activities of amrinone and AR-L57.

It has been suggested that amrinone and AR-L57 enhance cardiac contractility either by inhibiting phosphodiesterase activity or altering Ca++ homeostasis. Because these novel agents are potentially useful in the management of heart failure, it was of interest to more clearly define their mechanism(s) of action. Amrinone and AR-L57 caused concentration-dependent increases in the contractile states of either perfused guinea-pig hearts or cultured rat cardiomyocytes. To determine whether these actions might result from an increase in sarcolemmal Ca++ movement, the effects of these agents on Ca++ accumulation were studied in a simple system, dog erythrocytes. Both agents promoted erythrocyte Ca++ accumulation in time and concentration-dependent manners, effects that resulted primarily from increased Ca++ entry. However, because these effects were not measurable at inotropic drug concentrations and were apparent only after a 30-min incubation, they did not provide an explanation for the inotropic effects of these agents. Amrinone and AR-L57 inhibited dog heart phosphodiesterase activity (isozyme III) with EC50 values of 23 and 420 microM, respectively; however, only the inotropic responses to amrinone were attenuated by the muscarinic agonist, carbachol, thereby implying a cAMP (cyclic AMP)-dependent mechanism. In cultured ventricular cells, concentrations of amrinone (2 X 10(-4) M) and AR-L57 (3 X 10(-5) M) that caused maximal inotropic responses were associated with the activation of glycogen phosphorylase, but neither drug significantly increased the activation state of cAMP-dependent protein kinase. To further probe the effects of these drugs on intracellular cAMP and Ca++ metabolism, their effects on protein phosphorylation were studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyridines↗