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Biomedical subjects

K G Johnson

Publications and source records attributed to K G Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1976

Studies on the cellular and free lipopolysaccharides from Branhamella catarrhalis.

Cellular and free lipopolysaccharides obtained from Neisseria catarrhalis and Branhamella catarrhalis were found to be essentially identical. Both cellular and free lipopolysaccharides contained core-oligosaccharides of the following composition: D-glucose (4 mol), D-galactose (1 mol), 2-amino-2-deoxy-D-glucose (1 mol), and 3-deoxy-D-manno-octulosonic acid. Aldoheptose and phosphate components were below levels of detection. Several physical methods indicated that all core-oligosaccharide preparations were identical. Lipid A preparations from cellular and free lipopolysaccharides of both organisms were qualitatively and quantitatively similar; they were composed of decanoic acid, dodecanoic acid, 3-hydroxy dodecanoic acid, 2-amino-2-deoxy-D-glucose, phosphate, and ethanolamine. The results tend to justify the transfer of Neisseria catarrhalis to the genus Branhamella.

Amino Sugars↗
PubMed1976

Regionalization of perinatal care for the United States.

A scheme of regionalization is proposed in which a regional perinatal system within a defined geographic area permits access of the high risk mother-fetus and infant to the appropriate level of technology for improved perinatal outcome.

Child Health Services↗
PubMed1975

Financial impact of physician assistants on medical practice.

A study of revenues generated and expenses incurred by 12 physician assistants (MEDEX) who had held salaried positions for at least one year was conducted to determine their financial impact on primary-care practices. Daily charge logs were used to make annual estimates of MEDEX-generated revenues. One method of estimating annual revenues produced a mean of $28,190 per year, and a second method yielded a figure of $30,210 per year. Financial statements were used in two different ways to estimate annual expenses related to the employment of the MEDEX. One procedure indicated average costs of employment were $15,900, and the other $20,100. Ten of the 12 practices in the study experienced substantial gains of estimated revenue over expenses ascribed to the activities of the MEDEX.

Costs and Cost Analysis↗
PubMed1975

Molecular order in Acholeplasma laidlawii membranes as determined by deuterium magnetic resonance of biosynthetically-incorporated specifically-labelled lipids.

The first application of deuterium magentic resonance of specifically labelled lipids to the study of a natural biological membrane is described. Palmitic acid labelled at the terminal methyl group with deuterium was incorporated biosynthetically into the lipids of the plasma membrane of Acholeplasma laidlawii. The deuterium nuclear magnetic resonance spectra contain quadrupole splittings which yield directly order parameters for this region of the membrane. Below the growth temperature (37 degrees C) the spectra are indicative of lipid in both gel and liquid crystalline states. Above this temperature they demonstrate the existence of an entirely liquid crystalline membrane whose order parameter decreases rapidly with increasing temperature. Comparison with egg phosphatidylcholine over the same temperature range shows a more rapid change in order with temperature for the A. laidlawii membranes.

Acholeplasma laidlawii↗
PubMed1975

An outreach program for a rural medical school.

An outreach program for Dartmouth Medical School has been developed which utilizes rural communities in the education and training of medical students and residents in primary care. A correlated curricular track for primary care and a residency program have been established. The program is interdepartmental and administered by the dean, and services provided to patients are financed by fee-for-service. The cost incurred by the presence of residents and medical students is shared by the community and the medical school. The program is based on a close partnership between the medical school and the community in fulfilling their respective educational and service objectives.

Ambulatory Care↗
PubMed1975

Thermoregulatory changes induced by cholinomimetic substances introduced into the cerebral ventricles of sheep.

1 Thermoregulatory responses have been recorded from Welsh Mountain sheep exposed to warm, neutral or cold environments while injections of cholinomimetic drugs and/or their antagonists have been given into a lateral cerebral ventricle. 2. Carbachol and physostigmine inhibited panting of animals at high ambient temperature (ta), caused vasoconstriction and initiated shivering at neutral ta, and accentuated shivering at low ta. Rectal temperature (tre) invariably increased. Oxotremorine had apparently identical effects. 3. Nicotine and another ganglionic stimulant, the quaternary methyl derivative of dopamine, had no effects on thermoregulation. 4. Atropine given 10 min before injections of carbachol, physostigmine or oxotremorine completely inhibited their hyperthermic effects, but pretreatment with the ganglion-blocking drug, pempidine, caused no inhibition. The cholinergic synapses that respond to cholinomimetic drugs injected into the lateral cerebral ventricles of sheep are therefore muscarinic and not nicotinic. 5. When atropine was given to sheep exposed to cold, no detectable reduction of shivering occurred and tre decreased only slightly, even with doses of atropine far greater than needed to inhibit shivering induced by physostigmine. This may be because shivering is controlled by neural pathways unaffected by drugs administered intracerebroventricularly or because the cholinergic synapses activated by physostigmine do not carry the input from cold sensors.

Animals↗
PubMed1975

Sweat gland function in isolated perfused skin.

1. A technique for perfusion of skin has been used to investigate a possible neurochemical basis for the different patterns of sweating in domestic animals. Evaporative water loss was measured from excised trunk skin, ears or tails perfused with a nutrient Krebs solution, to which drugs were added as required. Perfused skin was observed to sweat in response to administration of sudorific drugs, and some features of the patterns of sweating were similar to those which could be induced by heating or by drugs in conscious animals. 2. In sheep and goat skin, injections of adrenaline, and to a lesser extent of noradrenaline, elicited brief sweat discharges but these were not sustained when the drugs were infused during 10-20 min. Injections of isoprenaline, carbachol, 5-HT, bradykinin, oxytocin and histamine were all ineffective. 3. Injections of adrenaline into cattle skin evoked longer-lasting sweat discharges, and infusions of adrenaline elicited continuous discharges. Injections of noradrenaline and sometimes of bradykinin caused only brief sweat discharges; other drugs were ineffective. 4. In horse and donkey skin, injections or infusions of noradrenaline, oxytocin and bradykinin elicited brief discharges of sweat. Infusions of isoprenaline caused a continuous and profuse outflow of sweat. Infusions of adrenaline also caused a continuous discharge which was usually biphasic in its onset. Other drugs were ineffective. 5. Assuming that the brief sweat discharges are due to myoepithelial contractions and the continuous discharges to sustained increases in secretion, equine sweat glands seem to have a alpha-adrenergically controlled myoepithelium and a beta-adrenergically controlled secretory mechanism. Sheep and goats may have a similar alpha-adrenergic control of the sweat gland myoepithelium but only a feeble sweat secretory mechanism. In cattle, an alpha-adrenergic mechanism appears to control sweat secretion, but the control of the myoepithelium is uncertain.

Animals↗
PubMed1975

Nutritional requirements of some non-pathogenic Neisseria grown in simple synthetic media.

Ten species of non-pathogenic Neisseria were grown in simple defined liquid media containing amino acids, biotin, nicotinic acid, calcium pantothenate, ferrous sulfate, magnesium sulfate, and potassium phosphate. Two of these Neisseria were induced to grow with glutamic acid as the carbon and nitrogen source. The remaining eight Neisseria grew in glutamic acid medium supplemented with from one to four additional amino acids, lactate, or lactate and glucose. A strain of N. flavescens grew in the absence of added growth factors whereas the remaining nine species of Neisseria required either biotin or nicotinic acid; pantothenate was required by two and was stimulatory for three of these species. Use of carbohydrates by the non-pathogenic Neisseria in synthetic medium was tested. Two strains failed to use any of the 14 carbohydrates tested; one strain used only glucose; the remaining seven strains used fructose, glucose, maltose, and sucrose to varying degrees.

Amino Acids↗
PubMed1975

Envelope proteins in Neisseria.

The proteins of the cell envelope of Neisseria sicca strain ATCC 9913 have been examined by SDS - polyacrylamide gel electrophoresis. Some 20 proteins were resolved from the total envelope fraction, and nearly all of these were found to be localized in the outer membrane. Preparations of the "free-endotoxin" fraction differ from the outer membrane only in lacking a few minor proteins. The behavior of several of the envelope proteins on electrophoresis can be modified by changing the temperature of sample solubilization, and also by alteration of the growth medium. Experiments with phosphate-limited cultures showed that certain periplasmic proteins are closely associated with free endotoxin. Mutations which result in altered outer membrane permeability to antibiotics were found to cause changes in cell envelope protein composition. A comparison of the envelope proteins of eight species of non-pathogenic Neisseria showed that each had a characteristic composition. A classification of the organisms based on the relatedness of the protein patterns seen on SDS-polyacrylamide gels was in close agreement with classifications based on more usual methods.

Anti-Bacterial Agents↗
PubMed1975

Cellular and free lipopolysaccharides of some species of Neisseria.

Cultures of eight non-pathogenic species of Neisseria grown in simple defined media released lipopolysaccharide (free lipopolysaccharide) by a process distinct from cellular autolysis. Analyses of the pure cellular and free lipopolysaccharides obtained from six species of Neisseria revealed that they were remarkably similar and were devoid of detectable O-antigen side chains. Three distinct types of core-oligosaccharides were demonstrated. Type I core-oligosaccharide was a branched structure of alpha-D-glucopyranosyl units (7 mol) terminated by a reducing end group of 3-deoxy-D-manno-octulosonic acid. Type II core-oligosaccharide contained D-glucose, 2-deoxy-2-amino-D-glucose, L-rhamnose, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid, phosphate, and ethanolamine in a molar ratio of 3:2:1:1:1:1:1. Type III coreoligosaccharide was composed of D-glucose, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid, and phosphate in a molar ratio of 3:3:1:1. Lipopolysaccharides of N. caviae and N. sicca contained type I core-oligosaccharides exclusively, while those of N. flava and N. perflava contained only type II core-oligosaccharide. Cellular lipopolysaccharide from N. cinerea contained core-oligosaccharides of types I and II in a ratio of 27:73, while the analogous preparation from N. flavescens contained core-oligosaccharide types II and III in a ratio of 21:4. Free lipopolysaccharides from these two organisms contained only one type of coreoligosaccharide. Lipid A components of all the lipopolysaccharide preparations were very similar being composed of about 25% by weight of dodecanoic acid, 3-hydroxy-dodecanoic acid, and 3-hydroxy-tetradecanoic acid.

Amino Sugars↗
PubMed1975

SDS-polyacrylamide gel electrophoresis of lipopolysaccharides.

Lipopolysaccharides (LPS) prepared from four different species of Neisseria have been separated by SDS-polyacrylamide gel electrophoresis. Each LPS possessed a characteristic mobility on gels. Examination of the effect of acrylamide concentration on migration illustrated that the basis of the separation was molecular size and not intrinsic charge.

Electrophoresis, Polyacrylamide Gel↗
PubMed1975

Impact of physician's assistants on patient visits in ambulatory care practices.

The addition of a physician's assistant to an ambulatory care practice increases the practice's productivity. Practices using physician's assistants (medexes) had a 12% increase in the number of patient visits during the first year of training and 1 3/4 years later had an average increase of 37%. The medex by himself provided care to 28% of the patients and, in company with the physician, to another 10%. No consistent changes across practices were noted in patient waiting times or time physicians spend with patients.

Acute Disease↗