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Biomedical subjects

R J Hart

Publications and source records attributed to R J Hart.

At least 37 records · Page 2Linked to original sources
PubMed1984

Susceptibilities of drugs to nitrosation under standardized chemical conditions.

Of 22 drugs with either a N,N-dimethylamino, N,N-diethylamino or N-morpholino group in the molecule, eight were converted to volatile N-nitrosamines by nitrosative cleavage in reactions of nitrite and drug in a molar ratio of 4:1 at pH 3. Under standardized conditions yields were greatest with aminopyrine and minocycline which contains two N,N-dimethylamino groups in the molecule. Oxytetracycline, chlortetracycline, tetracycline, promethazine, chlorpromazine, imipramine and disulfiram gave much lower yields and amitriptyline, clomiphene, clomipramine, dextropropoxyphene, diphenhydramine, disopyramide, erythromycin, mepyramine, methapyrilene, penicillin G procaine salt, procaine, tamoxifen, trimeprazine and tripelennamine yielded no detectable levels of volatile N-nitrosamines. Nitrosation products of 57 drugs were also examined by a group selective procedure estimating both volatile and non-volatile N-nitroso compounds. Virtually all of the yield obtained from aminopyrine or minocycline could be accounted for by N-nitrosodimethylamine (NDMA). However, compounds yielding excess N-nitrosamines compared to NDMA were obtained from the other three tetracyclines, presumably as a result of the cleavage of a methyl group from the N,N-dimethylamino substituent to form desmethyl-N-nitroso compounds. In general, the drugs giving the highest yields of N-nitroso compounds were those containing secondary rather than tertiary amino groups. A considerable range of susceptibilities towards nitrous acid was observed overall; ten drugs containing a secondary or tertiary amino- or amido- or hydrazido - group did not react with nitrous acid to form N-nitroso compounds.

Chemical Phenomena↗
PubMed1984

Corynebacterium ulcerans in humans and cattle in North Devon.

A case of Corynebacterium ulcerans sore throat in a community that drank raw milk from its own farm led to the discovery of another symptomless human infection. Eight cows in the herd were found to be infected and the intermittent pattern of excretion was demonstrated in another cow followed through its lactation. Further evidence of milk infected by C. ulcerans was found by examining all raw milk samples submitted to the laboratory. Two other human cases were diagnosed in Devon during the period of this investigation.

Animals↗
PubMed1983

The formation of nitrite and N-nitroso compounds in salivas in vitro and in vivo.

The considerable differences in salivary nitrite levels observed previously in subjects who had abstained overnight from dietary nitrate as completely as possible were again found in tests on ten separate days. A 25-fold variation was observed in the rate of production of nitrite in vitro during the incubation of salivas from different subjects with 16 mM-nitrate under standardized conditions. N-Nitroso compounds were detected as a group on 11/100 and 14/100 occasions after incubations in vitro without and with added nitrate, respectively. No significant changes in salivary nitrite level were found 1 hr after the volunteers had ingested water-borne nitrate at approximately the World Health Organization recommended limit for continuous use (50 mg NO-3/litre), but increases in nitrite concentration were consistently found after volunteers ingested nitrate in water at four times this concentration. Although the nitrite concentrations were markedly increased following the intake of nitrate at the higher level, the occurrence of N-nitroso compounds in the salivas of the volunteers was greater immediately prior to the ingestion of water-borne nitrate than 1 hr afterwards.

Female↗
PubMed1983

Report of a joint DMRQC/Organon field trial to detect hepatitis A IgM by ELISA.

The results of a field trial of a joint DMRQC/Organon ELISA kit for the detection of hepatitis A IgM antibody are reported. The participating laboratories were asked to use the kit to test a panel of 360 specimens consisting of duplicate coded samples of 180 sera. The panel was also tested by MACRIA in the Virus Reference Laboratory, Colindale. The ELISA was shown to be specific and sensitive giving good discrimination between acute and late convalescent hepatitis A sera. It was proposed that the same cut-off control as is used in the RIA (equivalent to 10 RIA units) should be adopted for the ELISA also.

Acute Disease↗
PubMed1983

Enzyme-linked immunosorbent assay (ELISA) for the detection of hepatitis Be antigen and antibody: report of a field trial.

A field trial of an enzyme-linked immunosorbent assay (ELISA) for the detection of the hepatitis Be markers is reported. It is simple to perform, is designed to be read by eye and does not require any expensive apparatus. When compared with a commercially available RIA kit for the detection of the same markers, ELISA was shown to be as sensitive as RIA for the detection of anti-HBe but slightly less sensitive for the detection of HBeAg. However if all specimens negative for both HBeAg and anti-HBe by ELISA are considered to be potentially infectious, the ELISA should prove to be as useful as RIA for determining the "e" status of HBsAg-positive patients and, therefore, provide a reliable indication of the risk of secondary spread of hepatitis B infection to contacts by needle stick accident, close personal contact or perinatal transmission.

Antibodies, Viral↗
PubMed1982

Pregnancy complicated by psittacosis acquired from sheep.

Two cases of chlamydial infection in pregnant women are described, the first serologically proved and the second suspected. In both cases the infection was probably contracted from sheep suffering with enzootic abortion. Both patients were farmers' wives who had helped their husbands and lambing and developed a non-specific febrile illness in late pregnancy. In the first case as there was no clinical improvement after 26 hours the patient was delivered by caesarean section of a live infant in good condition; the patient recovered fully. The second patient had presented a year earlier, the fetus had died in the uterus, and the patient himself died after spontaneous labour and forceps delivery 14 hours after admission. Both patients developed disseminated intravascular coagulation. As the casual agent in enzootic abortion in ewes has a predilection for the placenta, early delivery may be the management of choice in late pregnancy if infection with this organism if suspected.

Adult↗
PubMed1982

CGA-72662--a new sheep blowfly insecticide.

The efficiency of 2-cyclopropylamino-4, 6-diamino-s-triazine CGA-72662 (proposed common name: cyromazine) for the control of blowfly strike was tested in fly cage and field trials on sheep. The safety to sheep and physico-chemical properties of the compound as they relate to blowfly control were also assessed. When the sheep were thoroughly jetted with a solution of CGA-72662 containing 1g of active ingredient per litre, the mean incidence of fly strike in 7 field trials was reduced from 16.5% to 1.5% over a period of 9 weeks. The incidence of strike in the treated sheep in 2 insectary tests, which imposed levels of fly activity far in excess of that usually encountered in the field, was reduced from 93% and 73% in untreated sheep to 2% and nil respectively over a period of 8 weeks. Jetting with CGA-72662 solutions 100 times greater than the recommended concentration did not produce any side effects in sheep. Three treatments at twice the recommended concentration during the first trimester did not affect pregnant ewes nor their progeny. The compound was safe to use in combination with common anthelmintics and with sheep dips used for control of lice. CGA-72662 was stable in solution. No stripping occurred in dips and it persisted on wool for a considerable period. A satisfactory alternative to the organophosphorus insecticides has been found in CGA-72662, since it provided a substantial increase in residual protection against blowfly strike with a high degree of safety.

Animals↗
PubMed1981

A five-year study of influenza in families. Joint Public Health Laboratory Service/Royal College of General Practitioners working group.

A five year collaborative study of influenza in volunteer families from 1973-78 covered a period in which there were outbreaks every year but no major epidemics of influenza. Volunteers over the age of 15 years were bled before and after each of the five winters, and virus isolation was attempted from as many as possible when they reported episodes of illness. Children under 15 in the volunteer families were also swabbed when they were ill. Although most families experienced one or more attacks by influenza viruses, there was little transmission within families.

Adolescent↗
PubMed1981

Nonprotein neurotoxins.

Nonprotein neurotoxins are continuing to play a major role as molecular probes in studying nervous processes. They also have clinical importance as some of them, such as saxitoxin and its analogues, are the source of public health problems, or have potential use in therapy. This review covers clinical, biological, pharmacological, and chemical aspects of certain nonprotein neurotoxins, with emphasis on three well-known ones: tetrodotoxin, saxitoxin, and batrachotoxin. The distribution of the toxins is discussed as well as their symptomatology, treatment of affected patients, and effects of their structures on their physiological activity. With so many outstanding problems remaining in neuropharmacology, the study of nonprotein neurotoxins thrives as a fertile area of research.

Animals↗
PubMed1980

The ultrastructure of somatic neuromuscular junctions in the tick Amblyomma variegatum (Fabr.).

Peripheral nerve axons synapse with somatic muscle fibres in the tropical bont tick Amblyomma variegatum. Each fibre is innervated by numerous terminals; some of the axons synapse more than once. The nerve terminals on coxal muscle fibres contain agranular electron lucent vesicles 50 to 58 nm in size and have the specialised synaptic membranes characteristic of chemically transmitting nerve-muscle junctions. Some of the terminals on trochanteral muscle fibres additionally contain larger vesicles (90 nm) with electron dense cores, suggesting that these junctions operate with a different kind of neurotransmitter.

Animals↗