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Biomedical subjects

J D Johnson

Publications and source records attributed to J D Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1976

Determing the pulmonary excretion rate of carbon monoxide in newborn infants.

A simplified technique was devised for measurement carbon monoxide excretion rates in newborn infants. Determinations can be performed quickly and repetitively in a noninvasive manner, with a sensitivity sufficient for use even on small preterm infants. Resolution of the method is +/- 4.3 mul/h (SD); however, variations in infant respiration rate may cause much greater changes in actual excretion rate. Preliminary results with five full-term newborn agree to within 15% of previously reported data. The system will be used extensively in ongoing studies involving total bilirubin production as a function of gestational age.

Bilirubin↗
PubMed1976

A sequential study of various modes of skin and umbilical care and the incidence of staphylococcal colonization and infection in the neonate.

The rates of colonization and infection of newborns with coagulase-positive staphylococci were studied during five sequential periods using various modes of skin care in the nursery. Colonization and infection were low during the baseline period when total body bathing with 3% hexachlorophene was employed (period 1), but increased dramatically (80% colonization, 9.5% infection) when hexachlorophene was discontinued and replaced by Ivory Soap baths (period 2). Reinstitution of hexachlorophene (period 3) reduced both colonization and infection, but not to the low levels seen during period 1. A second Ivory Soap period (period 4) resulted in a return to high colonization (77%) and infection (11.5%) rates. During period 5, daily Ivory Soap baths were continued and bacitracin ointment was applied to the umbilical area at least three times daily. Colonization was reduced to 10% and infection to 3.0%. Bacitracin could not be detected in serum in 15 infants studied. Colonization with gram-negative enteric bacilli was highest while using hexachlorophene or Ivory-bacitracin, but no increase in gram-negative infections was seen. Colonization of newborns with non-group A beta-hemolytic streptococci was not influenced predictably with various modes of skin care. The local application of bacitracin is a safe and effective method of controlling staphylococcal colonization and disease for infants in nurseries.

1-Propanol↗
PubMed1975

DNA-binding proteins from Novikoff hepatoma cells.

In 0.05 M NaCl, 6-8% of the total soluble proteins from Novikoff hepatoma cells bind rapidly and reversibly to columns containing either heterologous or homologous DNA adsorbed to cellulose. These proteins can be eluted by buffer containing 2.0 M NaCl. 0.5-1% of the total protein exhibits a 7-17-fold preference for rat DNA over Escherichia coli DNA. 1-1.5% of the proteins bind DNA so strongly that elution cannot be effected by 4.0 M NaCl but can be accomplished by deoxyribonuclease I treatment of the columns. DNA-binding proteins eluted by 2.0 M NaCl were labeled with 125I or 131I and characterized by sodium dodecylsulfate-polyacrylamide gel electrophoresis and isoelectric focusing. These experiments indicate that DNA-binding proteins represent a discrete subset of the total soluble protein. Many similarities were noted between the major components of the homologous and heterologous DNA-binding fractions.

Animals↗
PubMed1975

Relationship between release of surface proteins and metabolic activation of sea urchin eggs at fertilization.

Macromolecular components are released from sea urchin eggs when their metabolism is activated at fertilization or by incubation in ammonia. When the released material is dialyzed, concentrated, and added back to partially activated eggs the rate of protein synthesis is suppressed to the level of the unactivated egg. The surface proteins of the unfertilized eggs can be labeled with 125I by a lactoperoxidase procedure. When fertilized or activated with various parthenogenetic agents, 15-25% of the total labeled protein is released; most of the label is associated with a 150,000-dalton glycoprotein. The extent of metabolic activation, as assessed by measuring increased protein synthesis, is correlated with the amount of surface label released. Several other proteins are released during activation but are not labeled by the lactoperoxidase procedure in the intact cell. We have not yet identified which of these components is responsible for suppressing protein synthesis, nor do we know if any of the other metabolic changes of fertilization such as K+ conductance and DNA synthesis are also suppressed. We suggest that these released components are surface molecules involved in maintaining the low metabolic state occurring at the end of oogenesis and that removal of these components during fertilization results in the release of the suppression of the egg.

Ammonia↗
PubMed1975

Nature of the surviving plaque-forming unit of reovirus in water containing bromine.

The initial inactivation of reovirus in water containing 3 to 7 microns M bromine as HOBr was very rapid. Electron microscopy revealed extensive physical damage to the virions in as little as 1 min, but none were degraded beyond recognition. As treatment time continued, the reaction rate decreased toward a plateau of resistance, usually at about the 10-4 survival level; still no particles were lost. Progeny grown from these resistant plaque-forming units (PFU) were no more resistant to HOBr than the parent cultures. Small-number aggregation (adhering groups of two to ten virions counted by electron microscopy) had no detectable effect on the level of persistant PFU. Large aggregates seemed to be involved. Sonic treatment at 20 kHz after bromine exposure increased survival PFU titer 10- to 43-fold. Virus exposed to light centrifugation prior to bromine treatment did not show the plateau of resistance. Surviving PFU sedimented faster in a shallow sucrose gradient than single virions. Large aggregates were apparently too few to be counted by electron microscopy, but their penetration and inactivation must be achieved by any disinfectant chosen to rid water of reovirus.

Animals↗
PubMed1975

A genetic study of lactose digestion in Nigerian families.

The ability to digest orally administered lactose was determined in individuals representing a number of Nigerian ethnic groups. The data are mainly presented as family pedigrees. In those families where both parents were unable to digest lactose, all of the progeny were lactose nondigestors. If one parent, usually of Northern garopena origin or of the Fulani tribe, could digest lactose, then the progeny contained some or all individuals who were capable of digesting the disaccharide. There was no difference in the results when either the mother or the father was the lactose digestor. Ten families were studied where one parent was of Europena or Yoruba-European origin (lactose digestor) while the other was proper Yoruba 0lactose nondigestor). From these matings, there were 18 lactose digestors and 11 lactose nondigestors. We have concluded that the ability to digest lactose is transmitted as an autosomal dominant and represents the mutated gene or a polymorphism.

Adult↗
PubMed1975

Activation of alveolar macrophages after lower respiratory tract infection.

Alveolar macrophage function has been studied in relation to bacterial infection of the lower respiratory tract. First, LRT macrophages were examined after exposure of rabbits to Listeria monocytogenes aerosols. Macrophages obtained from the LRT of animals 10 to 48 days after infection were activated, as evidenced by greater adherence to culture dishes and increased ability to ingest and kill both the original infecting organism and unrelated organisms, when compared to normal alveolar macrophages. Next, the in vitro effects on normal alveolar macrophages of incubation supernatants of control and antigen-stimulated lymphocytes (LRT and lymph node) from animals infected with L. monocytogenes or Streptococcus pneumoniae were evaluated. As manifested by increased adherence and phagocytosis, and an enhanced nonspecific bactericidal activity, alveolar macrophages were activated by the antigen-stimulated supernatants. These stimulated lymphocyte supernatants contain lymphokines (MIF), but the exact nature of the alveolar macrophage activating factor(s) remains to be determined. These observations, together with recent evidence that alveolar macrophages respond to lymphokines (MIF), suggest that the effector mechanism for cell-mediated immunity in the LRT is intact.

Aerosols↗