Search PubMed⌕ Search

Biomedical subjects

R Weiss

Publications and source records attributed to R Weiss.

At least 379 records · Page 21Linked to original sources
PubMed1982

Nonsense suppression in aminoacyl-t-RNA limited cells.

A number of nonsense alleles of lacZ exhibit phenotypic suppression (as much as a sixteen-fold increase in leakiness) during partial limitation for certain aminoacyl-tRNA species in relA mutant cells. Each responsive allele has its individual pattern of response to limitation for one or more amino acids or aminoacyl-tRNA's. The phenotypic suppression occurs only during limitation, and ceases once limitation is reversed. Suppression is much reduced by the presence of the relA+ allele or an allele of rpsL which restricts ribosomal ambiguity. In one case, the suppressed product has been identified by radioimmune assay and gel electrophoresis, and is a full-length lacZ protomer. Mechanisms are discussed whereby aberrations of translation at codons calling for an aminoacyl-tRNA species in short supply might lead to readthrough of a nearby nonsense codon.

Escherichia coli↗
PubMed1982

Cambodian disaster relief: refugee camp medical care.

The lack of available data impedes the efficient delivery of health care in disaster situations. We present organizational information and patient data based on review of 924 consecutive admissions seen during our three-month experience as refugee camp pediatricians at Khao-I-Dang Holding Center for Kampucheans in Thailand. Most patients had severe and multiple common diseases, with pneumonia, diarrhea, measles, and meningitis having the highest incidence. To optimize care, the gathering and distribution of epidemiologic data, the development of laboratory facilities and treatment protocols, standardization of supplies, and the initiation of programs for disease prevention must be stressed.

Adolescent↗
PubMed1982

Impaired metabolism of methylphenobarbital after a combined drug overdose: treatment by resin hemoperfusion.

A 38-yr-old woman who by history ingested 13 g methylphenobarbital, alcohol, and 6 g acetaminophen became comatose slowly over 4 d. Acute hepatic injury appeared to impair the oxidative N-demethylation of methylphenobarbital to its product, phenobarbital. On the eighth day after ingestion she was treated because of protracted coma with Amberlite XAD-4 resin hemoperfusion. Hemoperfusion, which removed 0.83 g methylphenobarbital and 2.10 g phenobarbital, led to transient clinical improvement. When supportive patient management fails to produce a satisfactory clinical course in a methylphenobarbital-intoxicated patient, hemoperfusion could be a useful adjunct to therapy.

Acetaminophen↗
PubMed1982

Effect of some enzyme inducers, fluids, and methionine-thiosulfate on induced acute aflatoxicosis in goats.

Groups of four 6- to 12-month-old male goats were injected intraruminally with a lethal dose (3 mg/kg of body weight) of aflatoxin B1 (AFB1). Drugs were administered parenterally before (pretreatment) or beginning 8 hours after goats were doses with AFB1. These drugs were phenobarbital (PB), phenylbutazone (PBZ), piperonyl butoxide (PRO), benzoflavones, water, and 5% glucose solution (D5W). Most groups given the drugs after AFB1 was administered also were given intraperitoneal injections of methionine-sodium thiosulfate (MET-TS) solution. Clinical signs of toxicosis, serum aspartate aminotransferase activities, serum bilirubin concentrations, duration of illness, mortality, and gross and microscopic pathologic findings taken together indicated that toxicosis was increased with MET-TS + PB therapy, PBZ pretreatment, PBZ therapy, benzoflavone pretreatment, benzoflavone therapy, MET-TS + benzoflavone therapy, and MET-tS + water therapy. Toxicosis was not altered appreciably by MET-TS + PBO therapy. Beneficial effects (less severe toxicosis) were produced by PB pretreatment; these effects were prolonged maintenance of strength, vigor, and appetite and (in 1 goat that recovered) absence of pathologic changes or serum bilirubin increase. Therapy with MET-TS + D5W (but not MET-TS alone) also lengthened maintenance of strength, vigor, and appetite, but did not prevent pathologic changes. The beneficial effect of MET-TS therapy reported in a previous study (AFB2 dosage of 4 mg/kg) was not observed with the 3 mg/kg lethal dose. In conclusion, therapy for acute aflatoxicosis with inducers of hepatic microsomal enzymes is ineffective (PBO) or contraindicated (PB, PBZ, benzoflavones). Therapy with D5W may be a useful adjunct to other therapeutic drugs, but multiple intraperitoneal injections of D5W may decrease survival time because of stress.

Aflatoxin B1↗
PubMed1982

Effect of enzyme inducers and inhibitors and glutathione precursor and depleter on induced acute aflatoxicosis in rabbits.

Male New Zealand White rabbits were treated with microsomal enzyme inducers, inhibitors of hemoprotein synthesis or action, and glutathione precursor and depletor before they were orally given the median lethal dose (LD50) of aflatoxin B1 (AFB1; 0.4 mg/kg) at the start of a 7-day experimental period. The drugs administered, mean duration of illness (hours), and survival percentage were as follows: controls (saline solution)-85, 50%; phenobarbital (PB)-100, 100%; phenylbutazone-115, 67%; benzoflavone-39, 17%; stanozolol-67, 67%; cobaltous chloride (CoCl2)-46, 67%; piperonyl butoxide (PBO)-88, 100% cysteine (CYS)-68, 100%; ethyl maleate-71, 83%. Signs of toxicosis included decreased feed and water consumption, weight loss, dehydration, lethargy, and emaciation; some rabbits died or were euthanatized. Clinico-pathologic changes included increased serum aspartate aminotransferase (AST) activity by 24 hours and bilirubin concentration by 48 to 72 hours after AFB1 was given. Grossly, livers were pale or tan and friable, with prominent lobular architecture. Kidneys of affected rabbits were pale to dark red. Microscopically, livers were normal or had lesions as great as extensive necrosis, hemorrhage, mineralization, and bile duct proliferation. Treatment of rabbits with PB, CoCl2, PBO, and CYS protected against AFB1 hepatic pathology, and PB, PBO, and CYS also had protective effect against lethality. Ethyl maleate provided some protection against lethality and increased serum AST activity and bilirubin concentration. Toxicosis was enhanced by benzoflavone; phenylbutazone and stanozolol had litte influence.

Acute Disease↗
PubMed1982

Toxicologic study of carboxyatractyloside (active principle in cocklebur--Xanthium strumarium) in rats treated with enzyme inducers and inhibitors and glutathione precursor and depletor.

Male rats (10 rats/group) were treated with phenobarbital (PB), phenylbutazone (PBZ), stanozolol (3 inducers of cytochrome P450-dependent enzymes), piperonyl butoxide (PBO; a P450 inhibitor), cobaltous chloride (CoCl2; an inhibitor of hemoprotein synthesis), 5,6-benzoflavone (BNF; an inducer of cytochrome P448 dependent enzymes), cysteine [CYS; a glutathione (GSH) precursor], or ethyl maleate (EM; a GSH depletor). The rats were then given a calculated LD50 dosage (13.5 mg/kg of body weight) of carboxyatractyloside (CAT) intraperitoneally. Clinical signs of toxicosis, duration of illness, lethality, gross lesions, and hepatic and renal histopathologic lesions were recorded. Seemingly, (i) CAT toxicosis has independent lethal and cytotoxic components (PBZ decreased lethality and cytotoxicity; CoCl2 decreased cytotoxicity but not lethality; BNF decreased duration of illness, and perhaps lethality, but not cytotoxicity); (ii) CAT cytotoxicity could be partly due to an active metabolite formed by de novo-synthesized, P450-/P448-independent hemoprotein (PBZ and CoCl2 had anticytotoxic effects, but PB, stanozolol, PBO, and BNF did not); (iii) CAT detoxification may occur partly through a hemoprotein-independent, PBZ-inducible enzyme, and partly through a P448-dependent (BNF-inducible) enzyme; and (iv) CAT detoxification apparently is not P450 or GSH-dependent because PB, stanozolol, and CYS had no beneficial effects, and PBO, CoCl2, and EM did not enhance toxicosis. Metabolism of CAT may have a role in its cytotoxic and lethal effects.

Animals↗
PubMed1981

Intrinsic birefringence signal preceding the onset of contraction in heart muscle.

An intrinsic birefringence signal with two components occurring before sarcomere shortening was measured in mammalian cardiac muscle. The second component was sensitive to the inotropic state of the muscle as affected by external calcium concentration and epinephrine but not by changes of resting length. The second component was absent in frog heart. These results suggest that the second component of the birefringence signal reflects the activity of the sarcoplasmic reticulum related to excitation-contraction coupling processes occurring prior to onset of contraction in mammalian cardiac muscle.

Action Potentials↗
PubMed1981

[Glioblastoma multiforme developing after a gunshot injury of the brain (author's transl)].

We report the case of a 28-year-old male who suffered a frontal penetrating gunshot injury with subsequent bifrontal brain abscess and subdural empyema, and five years later developed a large bifrontal tumour at the precise site of the meningo-cerebral scar and posttraumatic defect. Histological examination showed a glioblastoma multiforme adjacent to the dural scar and, in addition, old suture material was found within the glioma tissue. In spite of combined radiation and polychemotherapy the patient died eleven months after partial tumour resection. The temporal and local association of missile injury with subsequent recurred abscess and scar formation and the malignant glioma is highly suggestive of a causal relationship between trauma and the development of a brain tumour.

Adult↗