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Biomedical subjects

S Ehrlich

Publications and source records attributed to S Ehrlich.

48 records · Page 3Linked to original sources
PubMed1985

Effect of double-strand breaks on homologous recombination in mammalian cells and extracts.

We examined the effect of double-strand breaks on homologous recombination between two plasmids in human cells and in nuclear extracts prepared from human and rodent cells. Two pSV2neo plasmids containing nonreverting, nonoverlapping deletions were cotransfected into cells or incubated with cell extracts. Generation of intact neo genes was monitored by the ability of the DNA to confer G418r to cells or Neor to bacteria. We show that double-strand breaks at the sites of the deletions enhanced recombination frequency, whereas breaks outside the neo gene had no effect. Examination of the plasmids obtained from experiments involving the cell extracts revealed that gene conversion events play an important role in the generation of plasmids containing intact neo genes. Studies with plasmids carrying multiple polymorphic genetic markers revealed that markers located within 1,000 base pairs could be readily coconverted. The frequency of coconversion decreased with increasing distance between the markers. The plasmids we constructed along with the in vitro system should permit a detailed analysis of homologous recombinational events mediated by mammalian enzymes.

Animals↗
PubMed1982

Ceftizoxime kinetics and renal handling.

The kinetics and renal handling of ceftizoxime were examined after intravenous and intramuscular injection and the effect of probenecid on its excretion was investigated. Peak serum level after 1000 mg IV was 60.5 microgram/ml and half-life (t 1/2) was 1.4 hr. Peak serum level (40.9 microgram/ml) was reached 1 hr after 1000 mg IM. When probenecid was added to the 1000-mg IM dose the peak level was 44.3 microgram/ml at 1 hr and serum levels at 2, 4, 6, and 8 hr were all higher than after ceftizoxime alone (P less than 0.01). The 1.85-hr t 1/2 of ceftizoxime alone was extended to 2.29 hr when probenecid was added. Ceftizoxime was shown to be actively secreted by the renal tubule; this secretion was decreased by probenecid.

Anti-Bacterial Agents↗
PubMed1981

Kinetics and renal handling of cefonicid.

Cefonicid kinetics were determined after intravenous and intramuscular injection and the renal handling of the drug was examined, including the effect of probenecid on its excretion. Peak serum levels after 1000 and 500 mg intravenously was 221 and 91 micrograms/ml. The half-life (t1/2) was the same for both regimens (3.5 hr). Intramuscular injection of the 1000- and 500-mg doses resulted in peak serum levels of 112 and 40 micrograms/ml. When probenecid was given with the 500-mg dose, the peak serum level was 61 micrograms/ml and the time to peak level rose from 1.3 to 2.5 hr. The t1/2 after 1000 and 500 mg alone was much the same at 4.8 and 4.9 hr. The addition of probenecid to the 500-mg dose extended the t1/2 and 7.5 hr. Renal clearance, excretion, and secretion rates for cefonicid were reduced by the addition of probenecid. Cefonicid's long t1/2 and high blood levels may provide clinical efficacy with a single daily dose.

Adult↗
PubMed1978

Eye movements and integrating information across fixations.

A series of experiments was conducted in which a word or letter string initially appeared in parafoveal vision, followed by the subject's eye movement to the stimulus. During the saccade, the initially displayed stimulus was replaced by a word that the subject was asked to read. The results indicated that the types of prior parafoveal information studied facilitated the naming of the word. The effect was obtained when the subject made an eye movement and when the saccade was simulated. There was also evidence that attentional allocation was tied to the direction of the eye movement.

Eye Movements↗
PubMedDate not supplied

Cirrhosis: multiobserver analysis of hepatic MR imaging findings in a heterogeneous population.

To investigate the magnetic resonance (MR) imaging findings of hepatic cirrhosis and the potential of MR imaging in differentiating cirrhosis from other hepatic abnormalities, three observers with different levels of expertise in MR imaging (specialist, experienced radiologist, and novice with special training) reviewed hepatic MR imaging examinations of 52 patients with biopsy-proved presence (n = 29) or absence (n = 23) of cirrhosis. All examinations included motion-compensated T1-weighted, T2-weighted, and flow-sensitive gradient-echo images. For all three observers, linear signal irregularity was more accurate than other findings. For the final diagnosis of cirrhosis, the specialist was most sensitive (76% at high threshold, 97% at low threshold), followed by the novice with special training (31% and 79%, respectively). Specificity was 100% for all observers at high threshold and 78%, 96%, and 87% for expert, experienced, and trained novice observers, respectively, at low threshold. Sensitivity did not vary regardless of severity of fibrosis, as determined independently by a hepatopathologist. MR imaging has the potential of offering a comprehensive noninvasive evaluation of patients with suspected cirrhosis, but considerable expertise is required at present.

False Positive Reactions↗
PubMedDate not supplied

Cocaine abuse in pregnancy: effects on the fetus and newborn.

The outcome of infants born to cocaine-using drug dependent women was compared to that of infants of non-cocaine using drug dependent and non-drug dependent women. The study population included 150 pregnant women: 50 women used heroin and methadone plus cocaine, 50 used heroin and methadone minus cocaine, and 50 were non-drug dependent women. Significant differences were found between the cocaine and drug-free groups in infant birth weight, length, head circumference and Apgar scores, with the cocaine group having lower values for each variable. Average gestational age did not vary between the 3 groups. The cocaine group included 1 spontaneous abortion and 4 fetal deaths; non-cocaine drug dependent women had 2 fetal deaths, with none in the control group. Mean abstinence scores for 19 of the physiological and behavioral parameters were lower in the cocaine group than in the non-cocaine drug dependent women with the exception of vomiting and convulsions. These data suggest that: (1) infants born to drug dependent women have a poorer general outcome than those born to non-drug dependent women; (2) maternal cocaine use does not appear to increase the incidence of severe neonatal abstinence symptomatology; (3) pregnancies complicated by cocaine abuse have a greater chance for fetal loss resulting from both spontaneous abortions and fetal death; (4) infants born to cocaine abusing women had infants with decreased birth weight, head circumference, length and Apgar scores.

Cocaine↗
PubMedDate not supplied

The osmotic pressure of chondroitin sulphate solutions: experimental measurements and theoretical analysis.

We used equilibrium dialysis to measure the osmotic pressure of chondroitin sulphate (CS) solutions as a function of their concentration and fixed charge density (FCD) and the ionic strength and composition of the solution. Osmotic pressure varied nonlinearly with the concentration of chondroitin sulphate and in 0.15 M NaCl at FCDs typical of uncompressed cartilage (approximately 0.4 mmol/g extrafibrillar H2O) was approximately 3 atmospheres. Osmotic pressure fell by 60% as solution ionic strength increased up to about 1 M, but remained relatively constant at higher ionic strengths. The ratio of Ca2+ to Na+ in the medium was a minor determinant of osmotic pressure. The data are compared with a theoretical model of the electrostatic contribution to osmotic pressure calculated from the Poisson-Boltzmann equation using a rod-in-cell model for CS. The effective radius of the polyelectrolyte rod is taken as a free parameter. The model qualitatively reproduces the non-linear concentration dependence, but underestimates the osmotic pressure by an amount that is independent of ionic strength. This difference, presumably arising from oncotic and entropic effects, is approximately 1/3 of the total osmotic pressure at physiological polymer concentrations and ionic strength.

Calcium↗