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Biomedical subjects

C Baldwin

Publications and source records attributed to C Baldwin.

63 records · Page 4Linked to original sources
PubMed1979

Decreased sensitivity to interferon associated with in vitro transformation of X-ray-transformed C3H/10T1/2 cells.

We have compared the interferon sensitivity of parental 10T1/2 cells, having a phenotype characteristic of normal cells, with that of transformed cells isolated after X-irradiation of treatment with methylcholanthrene. Transformed cells were 10- to 20-fold less sensitive than the parental untransformed cells to the antiviral action of interferon and were also less sensitive to the inhibitory effect of interferon on cell multiplication. The decreased sensitivity of these cells to interferon is a useful marker of the transformed phenotype.

Animals↗
PubMed1978

A modified sedimentation method for counting platelets in blood.

A sedimentation method for counting human blood platelets is proposed which uses a fluid of sp.gr. i.057 at an osmolarity of 320 milliosmols. The fluid is a mixture of Lymphoprep and Isoton II. After centrifugation at about 200 platelets are counted on an electronic particle counter.

Blood Cell Count↗
PubMed1976

Preparation and characterization of hormone-sensitive, resealed erythrocyte ghosts.

A method for preparing resealed turkey erythrocyte ghosts is described which utilizes hypotonic lysis and resealing following restoration of isotonicity. The resealed ghosts are isolated above 55% sucrose. The resealed ghosts are shown to be capable of maintaining high intracellular K+ concentrations in the presence of a low K+ extracellular environment. When ATP and an ATP-regenerating system are included during the resealing stage, (R)-(-)-epinephrine- and NaF-stimulated cyclic AMP accumulation, which is linear for 20 min, can be demonstrated. The concentration of (R)-(-)-epinephrine producing a half-maximal response in resealed ghosts is 1.0 +/- 0.4 X 10(-6) M. This is the same as that for (R)-(-)-epinephrine in the intact erythrocyte. The resealed ghosts are impermeable to Ca2+, but Ca2+ inhibition of cyclic AMP accumulation is noted if the divalent cation ionophore. A-23187, is present or if Ca2+ is included during the resealing stage.

Animals↗
PubMedDate not supplied

Acute stimulation of ganglionic tyrosine hydroxylase activity by secretin, VIP and PHI.

We have examined the ability of a number of neuropeptides to increase tyrosine hydroxylase (TH) activity in the superior cervical ganglion in vitro. Secretin and vasoactive intestinal peptide (VIP) both increased TH activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, insulin, luteinizing hormone-releasing hormone, [D-Ala2, Met5]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin and VIP increased TH activity with an EC50 of 5 nM and 0.5 microM, respectively. The effects of these peptides were not altered by prior decentralization of the ganglia, by addition of hexamethonium (3 mM) and atropine (6 microM), or by lowering the concentration of calcium in the medium to 0.1 mM. Addition of carbachol (3 microM) potentiated the effects of both secretin and VIP on TH activity. Several gastrointestinal peptides with structural similarities to secretin and VIP were examined for their ability to increase TH activity. Glucagon, gastric inhibitory peptide and human pancreatic tumor growth hormone-releasing factor produced no effect at a concentration of 10 microM, while PHI increased enzyme activity.

Animals↗
PubMedDate not supplied

Low birth weight (LBW) infants' exploratory behavior at 12 and 24 months: effects of intraventricular hemorrhage and mothers' attention directing behaviors.

Medically high-risk (HR), low birth weight (LBW) preterm infants (n = 11) with significant degrees of intraventricular hemorrhage (IVH) were seen at 12 and 24 months of age. This HR group was compared with a low-risk (LR) LBW preterm group (n = 16) with respiratory distress syndrome or mild grades of IVH, and a normal full-term (FT) group (n = 12). Infants and their mothers were observed in a 10-min toy-centered play interaction to determine if more advanced exploratory play occurred in association with specific maternal attention-directing behaviors. Results showed that the FT infants were able to respond with advanced exploratory play to unstructured as well as structured strategies, but that higher level play for the LR infants was associated with structured strategies. The HR infants showed fewer play responses than the other two infant groups regardless of whether mothers used structured or unstructured strategies. All infant groups showed more exploratory play behavior in relation to mothers' maintaining versus redirecting behavior.

Attention↗
PubMedDate not supplied

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