Search PubMed⌕ Search

Biomedical subjects

E Levin

Publications and source records attributed to E Levin.

At least 73 records · Page 4Linked to original sources
PubMed1989

Effect of antineoplastic drugs and estradiol on leucine uptake and proliferation of Ehrlich tumor cells.

Antineoplastic drugs (methotrexate, 5-fluorouracil, adriamycin) arrest the proliferation of Ehrlich ascites tumor cells in mice but have no influence on L-leucine uptake in vitro. Tamoxifen does not influence either process. Estradiol increases both the cellular proliferation and the amino acid uptake. The absence of estrogen receptors in the cells indicates that the hormone acts on cellular proliferation through mechanisms other than activation of DNA replication, such as stimulation of amino acid transport.

Animals↗
PubMed1988

Hydrolysis of 3H-bambuterol, a carbamate prodrug of terbutaline, in blood from humans and laboratory animals in vitro.

Tritiated bambuterol, a bis-dimethylcarbamate prodrug of terbutaline, was incubated in vitro with blood from both sexes of the following species: man, guinea pig, rat, mouse, dog and rabbit. The rates of hydrolysis of bambuterol to its monocarbamate derivative and further to terbutaline were measured. Large species variations were observed, e.g. blood from two of the human subjects was 15-fold more active than blood from the male rats. The rate of terbutaline formation as a function of initial bambuterol concentration was investigated in human plasma, and was found to describe a bell-shaped curve. Several pieces of evidence indicated that butyrylcholinesterase (EC 3.1.1.8) is the blood enzyme predominantly responsible for hydrolysis of bambuterol, although minor contributions from other esterases cannot be excluded. An exception may be blood from the rabbit, where the kinetics of the hydrolysis was different than in blood from the other species. The kinetics of bambuterol hydrolysis is discussed on basis of the established mechanism of carbamate interactions with cholinesterases, and the high affinity of bambuterol for butyrylcholinesterase.

Adult↗
PubMed1988

Chronic neuroleptics alter the effects of the D1 agonist SK&F 38393 and the D2 agonist LY171555 on oral movements in rats.

Vacuous oral movements (OMs) in rats chronically administered haloperidol (HAL), fluphenazine (FLU), or no drug were studied following injections of one of three doses of either a D1 agonist (SK&F 38393) or a D2 agonist (LY171555). Oral movements were observed via closed-circuit television and simultaneously recorded using a computerized video analysis system which measured the distance between two fluorescent dots painted above and below the rat's mouth. SK&F 38393 induced a dose-dependent increase in tremorous oral movements and repetitive chewing movements in the controls; this effect was more pronounced in rats treated with chronic HAL or FLU, both during chronic neuroleptic treatment and even more so when they were tested after drug withdrawal following 5 or 14 months of chronic neuroleptic administration. Conversely, LY171555 produced an inhibition of oral activity at all dose levels in controls. This inhibition was attenuated during chronic administration of HAL or FLU, but returned to control levels (without any signs of supersensitivity) when the animals were retested shortly after discontinuation of neuroleptics. These results indicate that heightened oral movements in rodents following chronic neuroleptic administration can be more clearly induced by D1 than by D2 receptor activation.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Opposite effects of a D1 and a D2 agonist on oral movements in rats.

Oral movements in rats administered one of three doses of either a D1 agonist (SK&F 38393) or a D2 agonist (LY171555) were observed via closed-circuit television and simultaneously recorded using a computerized video analysis system which measured the distance between two fluorescent dots painted above and below the rat's mouth. The D1 agonist SK&F 38393 induced a dose-dependent increase in tremorous oral movements, tongue protrusions, and, at the highest dose, increased repetitive chewing movements. Conversely, the D2 agonist LY171555 produced an inhibition or oral activity at all dose levels. At the lowest dose tested this appeared to reflect a non-specific decrease in activity, for there was an inhibition of all categories of behavior measured, as well as of all amplitudes of computer-scored movements and slow, sluggish movements were recorded. But higher doses of LY171555 induced hyperactivity and stereotyped, repetitive head movements whereas chewing movements, tremorous oral movements, and tongue protrusions were still decreased. D1 and D2 dopamine receptors appear to have opposite effects on oral movements.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Tremorous mouth movements in rats administered chronic neuroleptics.

Oral movements (OMs) in rats administered chronic haloperidol (HAL) were quantified simultaneously by a human observer and via a computerized video analysis system which monitored the distance between the upper and low lips using TV images. The human observer data indicated that during HAL administration the total duration of OMs was initially decreased, gradually returned to levels slightly above controls, and then increased substantially upon drug withdrawal. The computer records confirmed these findings and further indicated that after prolonged HAL administration a syndrome developed in which large-amplitude OMs remained suppressed but OMs of the smallest detectable amplitudes increased. Upon drug withdrawal, these small OMs increased in amplitude and rhythmicity, developing into repetitive tremors.

Animals↗
PubMed1984

Increased risk for cancer of the breast due to previous medication.

Fifteen patients presenting one or more risk factors for cancer of the breast, who also received medication with prolactin-stimulating effects, were selected. The medication was by hormone derivatives or by non-hormone drugs used for processes other than oncologic . In all cases the medication was for long periods, three or more years, with the exception of one case, where the correlation with the unfavourable evolution of the cancer process was more evident. In patients presenting the classic risk factors for cancer of the breast, it is recommended to avoid the prescription of drugs having a prolactin-stimulating effect. The association of both circumstances (risk factors and prolactin-stimulating medication) is considered as an increased risk for cancer of the breast.

20-alpha-Dihydroprogesterone↗
PubMed1983

A prospective randomized trial of methotrexate versus cisplatin in the treatment of recurrent squamous cell carcinoma of the head and neck.

A prospective randomized study was conducted to determine the relative effectiveness, toxicity and tolerance of methotrexate (MTX) versus cisplatin (DDP) in patients with recurrent head and neck squamous cell carcinoma. Forty-four patients were randomized to receive either MTX, 40 mg escalated to 60 mg/m2 IV push weekly, or DDP, 50 mg/m2 6 hour infusion days 1 and 8 every 4 weeks. All patients had objectively measurable disease and a performance status greater than 60% (Karnofsky scale). All had been treated with surgery and/or radiotherapy. No patients had prior chemotherapy. Prior treatment, performance status, and site of primary disease were comparable in both groups. Complete and partial objective responses were achieved in 23.5% of the MTX group and 28.6% of the DDP group (P = 0.51). Median duration of response was 84 days in the MTX group and 92 days in the DDP group. Median survival of patients was 6.1 months with MTX and 6.3 months with DDP. Mucositis was noted in 38% of patients in the MTX group (P = 0.001) compared to none in the DDP group. Vomiting occurred in 87% of patients in the DDP group (P less than .0001) compared to 10% of patients in the MTX group. This study demonstrates that in the treatment of recurrent head and neck squamous cell carcinoma, MTX and DDP are equally effective, although MTX appears to be better tolerated.

Carcinoma, Squamous Cell↗
PubMed1982

Dopamine regulates canine plasma beta-endorphin-immunoreactivity levels.

Intravenous administration of the dopamine antagonists domperidone and metoclopramide elevates canine plasma beta-endorphin immunoreactivity. Pretreatment with dopamine, but not dexamethasone, inhibits this effect. Sephadex G-50 chromatography shows that this response is due to beta-endorphin-like peptides, not beta-lipotropin. These findings indicate that pituitary beta-endorphin secretion is tonically inhibited by dopamine and suggest that the intermediate lobe is the source of this secretion.

Animals↗
PubMed1982

Correlation of single and serial CEA determinations with the clinical evolution of cancer patients.

The correlation between CEA results and the clinical evolution of 56 patients with breast and colorectal cancer, was studied. In mammary cancer (41 patients) there was a correspondence of 75% between single initial CEA values and clinical state at the time of the determination. For colorectal cancer patients the correspondence was 80%. A follow up of the patients during 4 years permitted the evaluation of serial CEA results in the prognosis of the disease. Two or more consecutive CEA results with the same significance (increased or normal) correlated better than single values with the clinical evolution of the disease (93% of correspondence). Normal values in patients with active disease were indicative of favourable prognosis; the appearance of single values above normal but below three times the upper normal limit, do not justify changes in the installed therapy. Two or more consecutive increased results are indicative of present or future deterioration of the patient. Cases of non-correspondence between consecutive serial. CEA results and clinical evolution of the patient are considered as "real false results" (7%). Serial CEA determination resulted very useful in the follow up of the oncological patient in the frame of other laboratory and diagnostic means, as a part of the periodic clinical control.

Breast Neoplasms↗
PubMed1981

The mini-Wright expiratory peak flow meter.

The purpose of this study was to compare the recently modified mini-Wright peak flow meter with the Wright peak flow meter. One hundred adult patients were arbitrarily divided into two groups, based on their average peak flow on the mini-Wright device. A strong positive correlation in excess of 0.90 was shown. We believe that the smaller, cheaper device is as accurate as the Wright peak flow meter.

Adult↗
PubMed1981

Isobaric tetracaine spinal anesthesia and the lithotomy position.

The extent and pattern of anesthesia produced by hyperbaric and by isobaric 0.5% tetracaine spinal anesthesia were compared in this blind-observer, randomized study of 103 spinal anesthetics performed in 98 patients having genitourinary surgery in the lithotomy position. Pinprick stimulation showed no significant differences in maximum segmental sensory levels, times to maximum level, or duration of anesthesia for isobaric as compared to hyperbaric tetracaine. No parameters were significantly altered by barbotage of isobaric tetracaine solutions. With injections given to patients in the sitting position and with patients subsequently maintained in a horizontal lithotomy position before being put in the lithotomy position, the addition of dextrose to tetracaine solutions injected at room temperature into the subarachnoid space does not significantly alter the cephalad spread of spinal anesthesia.

Adult↗
PubMed1981

Density of normal human cerebrospinal fluid and tetracaine solutions.

Density and specific gravity (SG) were determined at two or more temperatures between 23 and 37 C for 15 samples of normal human cerebrospinal fluid (CSF) and CSF mixed with tetracaine, and for tetracaine solutions commonly used for spinal anesthesia. Density was determined from measured weight and volume, and SG was calculated using the density of water at the same temperature. With 95% confidence limits, SG of normal human CSF at 37 C ranges from 1.0063 to 1.0075, less variation than previously reported. Changes in temperature altered the densities of dextrose, tetracaine, and CSF, alone or in combination, in a parallel manner, but SG remained constant for each solution over the observed temperature range.

Adult↗