Search PubMed⌕ Search

Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 703 records · Page 39Linked to original sources
PubMed1978

Emergency geriatric surgical admissions.

The emergency surgical work load created by patients aged 80 and over in a district hospital was assessed and the results of treatment examined. Over one year 248 patients aged 80 or over were admitted as emergencies, and the overall mortality rate was 21.8%. When terminal disease was excluded mortality rate was 12.5%. These elderly patients had an average length of stay in the acute surgical ward of 14.7 days compared with a mean of 8.4 days for all patients, and all but seven patients were discharged to their original place of referral.Elderly patients do exacerbate the bed shortage in acute surgical wards because they tend to stay longer than younger patients, but these elderly surgical patients imposed only a small load on the inpatient geriatric services, as 78% were discharged straight to their own homes and a further 17% went home after a period on the surgical convalescent wards.

Aged↗
PubMed1978

Purification, characterization, and action-pattern studies on the endo-(1 linked to 3)-beta-D-glucanase from Rhizopus arrhizus QM 1032.

The extracellular (1 linked to 3)-beta-D-glucanase [(1 linked to 3)-beta-D-glucan glucanohydrolase, EC 3.2.1.6] produced by Rhizopus arrhizus QU 1032 was purified 305-fold in 70% overall yield. This preparation was found to be homogeneous by ultracentrifugation (sedimentation velocity and equilibrium studies), electrophoresis on acrylamide gel with normal, sodium dodecyl sulfate, and urea-acetic acid gels, and upon isoelectric focusing. The amino acid composition of the enzyme has been determined and it possesses a carbohydrate moiety compose of mannose and galactose (in the ratio approximately 5:1) that is linked to the protein through a 2-acetamido-2-deoxyglucose residue. The molecular weight, as determined by equilibrium sedimentation, is 28,800 and this number was confirmed by electrophoresis on gels of sodium dodecyl sulfate. The enzyme does not possess subunit structure. It hydrolyzes its substrates with retention of configuration and possesses transglycosylating ability. The rates of hydrolysis of a wide variety of substrates were determined, and its action pattern on a series of oligosaccharides containing mixed (1 linked to 3)-, (1 linked to 4)-, and (1 linked to 6)-beta-D-glucopyranosyl residues was investigated. The enzyme favors stretches of beta-D-(1 linked to 3) linkages, but it can hydrolyze beta-D-(1 linked to 4) linkages that are flanked on the non-reducing side with stretches of beta-D-(1 linked to 3) links. The enzyme will not act on (1 linked to 6)-beta-D-glucosyl linkages located in stretches of beta-D-(1 linked to 3) and will not act on (1 linked to 3) beta-D-glycosidic linkages involving sugars other than D-glucose.

Glucan Endo-1,3-beta-D-Glucosidase↗
PubMed1978

Folate antagonists. 10. Synthesis and antimalarial effects of 6-[[(aryl and aralkyl)amino]methyl]-2,4-pteridinediamines and -pteridinediamine 8-oxides.

Various 6-[[(aryl and aralkyl)amino]methyl]-2,4-pteridinediamines and their 8-oxides have been synthesized for antimalarial evaluation. Condensation of 3-amino-6-(bromomethyl)-2-pyrazinecarbonitrile 4-oxide (V) with the appropriately substituted amine afforded a series of 3-amino-6-[[(aryl and aralkyl)amino]methyl]-2-pyrazinecarbonitrile 4-oxides VI. Deoxygenation gave the corresponding pyrazines VII. Cyclization of VI and VII with guanidine then produced the desired 6-(aminomethyl)-2,4-pteridinediamine N-oxides VIII and teridinediamines IX, respectively. Formylation of 6-[[(3,4-dichlorophenyl)amino]methyl]-2,4-pteridinediamine gave N-[(2,4-diamino-6-pteridinyl)-methyl]-N-(3,4-dichlorophenyl)formamide. The N-oxides VIII did not exhibit significant activity against Plasmodium berghei infections in mice. Activity among the 2,4-pteridinediamines IX was generally poor with the exception of the 3,4,5-trimethoxyphenyl and 1-naphthalenyl analogues which showed strong suppressive activity at doses ranging from 80 to 640 mg/kg. Furthermore, several of the 2,4-pteridinediamines exhibited potent prophylactic activity against Plasmodium gallinaceum infections in the chick and also showed strong antibacterial action against Streptococcus faecalis and Staphylococcus aureus.

Animals↗
PubMed1978

Folate antagonists. 11. Synthesis and antimalarial effects of 6-[(aryloxy- and arylthio-)methyl]-2,4-pteridinediamines and -pteridinediamine 8-oxides.

Condensation of 3-amino-6-(bromomethyl)-2-pyrazinecarbonitrile 4-oxide with 4-chlorophenol gave 3-amino-6-[(4-chlorophenoxy)methyl]-2-pyrazinecarbonitrile 4-oxide (1), which was deoxygenated to obtain the de-N-oxide 4. Cyclization of 4 and 1 produced 6-[(4-chlorophenoxy)methyl]-2,4-pteridinediamine and the 8-oxide, respectively. 6-[(Arylthio)methyl]-2,4-pteridinediamines and their 8-oxides were produced analogously. Controlled oxidation of the former gave the anticipated sulfoxide 12 and sulfone 13. None of these compounds showed significant activity when tested against lethal Plasmodium berghei infections in mice or a select list of bacteria in vitro.

Animals↗
PubMed1978

Folate antagonists. 12. Antimalarial and antibacterial effects of 2,4-diamino-6-[(aralkyl and alicyclid)thio-, sulfinyl-, and sulfonyl]quinazolines.

A series of 2,4-diamino-6-[(aralkyl and alicyclic)thio-, sulfinyl-, and sulfonyl]quinazolines was prepared via condensation of 5-chloro-2-nitrobenzonitrile or 5,6-dichloro-2-nitrobenzonitrile with the appropriate aralkyl or alicyclic thiopseudourea, reduction of the resulting 2-nitro-5-[(aralkyl or alicyclic)thio]benzonitrile with stannous chloride to the amine, and cyclization with chloroformamidine hydrochloride. Oxidation was effected with hydrogen peroxide or the bromine complex of 1,4-diazabicyclo[2.2.2]octane. These analogues when examined for suppressive activity against drug-sensitive lines of Plasmodium berghei in mice were not as active as 2,4-diamino-6-[3,4-dichlorobenzyl)amino]quinazoline (Ia).

Animals↗
PubMed1978

Folate antagonists. 13. 2,4-Diamino-6-](alpha,alpha,alpha-trifluoro-m-tolyl)thio]quinazoline and related 2,4-diamino-6-[(phenyl- and naphthyl)thio]quinazolines, a unique class of antimetabolites with extraordinary antimalarial and antibacterial effects.

An array of nonclassical thioquinazoline analogues (VIII) of methotrexate was prepared by cyclization of the requisite 2-amino-5-(arylthio)benzonitrile with chloroformamidine hydrochloride (28--79%). The aminonitrile precursors were obtained by SnCl2-HCl reduction (28--99%) of the corresponding 2-nitro-5-(arylthio)benzonitriles, which were synthesized by the condensation of the appropriate 5-chloro-2-nitrobenzonitriles with various arylthiols (36--83%). Many of the thioquinazolines (VIII) showed suppressive antimalarial activity comparable with or superior to chloroquine, cycloguanil, and pyrimethamine against drug-sensitive lines of Plasmodium berghei in mice and Plasmodium gallinaceum in chicks, and several displayed potent prophylactic activity with P. gallinaceum. Moreover, the thioquinazolines retained potent antimalarial effects against chloroquine-, cycloguanil-, pyrimethamine- and DDS-resistant lines of P. berghei in mice and against chloroquine- and pyrimethamine-resistant strains of Plasmodium falciparum in owl monkeys. The most active compound, namely, 2,4-diamino-6-[alpha,alpha,alpha-trifluoro-m-tolyl)thio]quinazoline, was designated for preclinical toxicological studies. Numerous substances exhibited in vitro activity against a broad spectrum of pathogenic bacteria at concentrations of less than 0.25 microgram/mL. The thioquinazolines also prove to be potent folate antagonists, causing 50% inhibition of Streptococcus faecalis R (ATCC 8043) at drug concentrations ranging from 0.2 to 2.0 ng/mL. Structure--activity relationships are discussed.

Animals↗
PubMed1978

Relationship between oestrogen-receptor content and histological grade in human primary breast tumours.

A series of 300 patients presenting consecutively with primary operable breast cancer has been studied. A significant correlation was found between oestrogen-receptor (ER) content and histological grade: the better-differentiated tumours rarely lacked receptor. This correlation was significant only in women defined as post-menopausal. Data on early recurrence of disease indicate a worse prognosis for women in whom primary tumours are ER-.

Adult↗
PubMed1978

Erythrocyte entry by malarial parasites. A moving junction between erythrocyte and parasite.

Invasion of erythrocytes by merozoites of the monkey malaria, Plasmodium knowlesi, was investigated by electron microscopy. The apical end of the merozoite makes initial contact with the erythrocyte, creating a small depression in the erythrocyte membrane. The area of the erythrocyte membrane to which the merozoite is attached becomes thickened and forms a junction with the plasma membrane of the merozoite. As the merozoite enters the invagination in the erythrocyte surface, the junction, which is in the form of a circumferential zone of attachment between the erythrocyte and merozoite, moves along the confronted membranes to maintain its position at the orifice of the invagination. When entry is completed, the orifice closes behind the parasite in the fashion of an iris diaphragm, and the junction becomes a part of the parasitophorous vacuole. The movement of the junction during invasion is an important component of the mechanism by which the merozoite enters the erythrocyte. The extracellular merozoite is covered with a prominent surface coat. During invasion, this coat appears to be absent from the portion of the merozoite within the erythrocyte invagination, but the density of the surface coat outside the invagination (beyond the junction) is unaltered.

Animals↗
PubMed1978

Neurophysiologic syndromes in stroke as predictors of outcome.

Outcomes in self-care following rehabilitation in 226 patients were correlated with 11 stroke syndromes, reflecting several pathophysiologic disturbances subsequent to either infarction or hemorrhage in cerebral or vertebro-basilar vessels. Self-care was scored on a 20-point scale for bed movements, transfers, feeding, dressing, personal hygiene, and bathing. Interjudge error among therapists did not exceed 2.5%. Mean score in left cerebral infarction without aphasia was used as a referent value. Scores in left cerebral infarction with aphasia and right parietal lobe syndrome with and without spatial agnosia were similar to the referent. Brain stem dysfunction with spasticity and right cerebral infarction with paresis and spatial agnosia fell below the referent value (Pless than 0.05). Higher levels were achieved in the syndromes of left and right anterior cerebral artery territories, brain stem dysfunction with ataxia, and left parietal lobe syndrome with comprehension aphasia, although t-values were not significant. Length of stay among the 11 groups was fairly uniform except for the group with brain stem dysfunction with spasticity and the group with left hemiplegia with spatial agnosia. These groups indicated rather severe disabilities. Aside from neurologic dysfunction the range of scores was influenced by associated cardiopulmonary involvement.

Activities of Daily Living↗