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Biomedical subjects

K Baker

Publications and source records attributed to K Baker.

At least 109 records · Page 6Linked to original sources
PubMed1989

Homeward bound. Discharge teaching for parents of newborns with special needs.

This article presents the complex work that professionals and parents must accomplish together prior to the discharge of a very ill or premature infant. Nurses play a critical role in this work by coordinating and directing the discharge teaching process. This process begins with the establishment of trusting relationships with parents and includes an assessment of the family's feelings, readiness to learn, and resources. A written teaching plan flows from this assessment and includes specific teaching topics germane to the individual child. A case manager coordinates the implementation of the plan and the evaluation of the learner's ability to care for the child independently in the home. Although time consuming and challenging, adequate discharge teaching in the NICU is critical to the successful integration of these special children into the family unit.

Homemaker Services↗
PubMed1988

Alpha-substituted thiobutyrolactones potentiate GABA currents in voltage-clamped chick spinal cord neurons.

The effect of the experimental anticonvulsant, alpha-ethyl,methyl thiobutyrolactone (alpha-EMTBL), on gamma-aminobutyric acid (GABA) currents was examined in cultured chick spinal cord neurons using gigaseal recording techniques. alpha-EMTBL potentiated GABA responses in a dose-dependent fashion with half-maximal effect at 7 microM. alpha-EMTBL also augmented the response to maximal doses of GABA. In competition experiments, alpha-EMTBL relieved the block of GABA currents produced by saturating concentrations of picrotoxinin whereas diazepam and phenobarbital did not. At a single channel level, alpha-EMTBL increased the probability of opening GABA channels without significantly altering the mean channel open time or the single channel conductance. These results indicate that alpha-EMTBL potentiates GABA responses and has properties which distinguish it from benzodiazepines or barbiturates.

4-Butyrolactone↗
PubMed1988

Effect of vagotomy on biliary-tract motor activity in the opossum.

In this study, we evaluated the effect of truncal vagotomy in the opossum on changes in gallbladder and sphincter-of-Oddi (SO) contractile activity that occur normally during fasting and after a meal. In six animals, bipolar electrodes were implanted on the SO, gastric antrum, duodenum, and jejunum. A catheter secured in the gallbladder fundus was used to monitor gallbladder volume. After control studies, truncal vagotomy and pyloroplasty were done in each animal. Before vagotomy, the SO exhibited cyclic changes in spike-burst rate, from 2 to 5/min, that were synchronized with corresponding phases of the duodenal MMC cycle. The gallbladder exhibited partial emptying during the second half of the duodenal MMC cycle with refilling during the first half of the next cycle. By two weeks after vagotomy, the MMC-related changes in SO and gallbladder contractile activity were normal. In contrast, vagotomy retarded the increase in SO spike-burst rate and delayed as well as diminished the pronounced gallbladder emptying that normally occurs after a meal. The same effects were observed for changes in SO and gallbladder activity induced by intraduodenal infusion of Isocal. After vagotomy, the SO and gallbladder exhibited exaggerated responses to intravenous infusion of CCK-OP or motilin. We conclude that truncal vagotomy in the opossum does not affect the fasting pattern of SO and gallbladder contractile activity, but it significantly alters the normal postprandial pattern of enhanced SO spike-burst rate and pronounced gallbladder emptying. The precise mechanism(s) whereby vagotomy produces these changes remains to be determined.

Action Potentials↗
PubMed1988

Kainic acid evokes a potassium efflux from astrocytes.

Cultured astrocytes are depolarized by excitatory amino acids such as kainic acid. In these experiments we tested the hypothesis that the kainic acid-induced depolarization also causes an efflux of K+ from astrocytes in the rat. Using K+-sensitive microelectrodes we measured a K+ efflux from cultured astrocytes during the perfusion of kainic acid. The effects of kainic acid were then tested on glial cells in the neuron-free CA3 region of kainic acid-lesioned hippocampus. Glial cells were depolarized by kainic acid and an efflux of K+ was recorded. These effects are most likely due to direct effects on the glial cells because histological examination of the hippocampus showed this area to be free of neurons. Therefore it is hypothesized that kainic acid and any transmitter that depolarizes glial cells, will increase neuronal excitability indirectly by a K+ efflux from glial cells. This will have widespread implications for iontophoretic studies of transmitter actions.

Animals↗
PubMed1988

Radionuclide bone imaging findings in recurrent calvarial infarction in sickle cell disease.

A patient with sickle cell disease developed bi-parietal calvarial infarctions, and subsequently developed bi-frontal calvarial infarctions. The findings on [99mTc]MDP bone imaging showed decreased activity in the parietal and frontal regions during the phase of acute infarction and increased activity in the parietal region during the later healing phase. Thus the findings on radionuclide bone imaging in cortical infarcts will depend upon the stage of the condition.

Adolescent↗
PubMed1987

Role of SecA and SecY in protein export as revealed by studies of TonA assembly into the outer membrane of Escherichia coli.

The growth of secAts or secYts mutants at the restrictive temperature has been shown to inhibit the export of many outer membrane proteins. We report here that in two secAts strains the rate of incorporation of newly synthesized protein into both inner and outer membrane fractions decreased by about 70% at the restrictive temperature. The export of the outer membrane protein TonA was used as a model system in which to study the effects of SecA or SecY inactivation. pre-TonA that accumulated at the restrictive temperature was found to co-sediment with the outer membrane fraction. However, the precursor was sensitive to protease and did not float up a sucrose gradient with the membrane fractions. It was therefore concluded that pre-TonA was not integrated into the outer membrane fraction but probably accumulated in the cytoplasm. Studies on the rate of processing of pre-TonA, pulse-labelled at the restrictive temperature then chased at the permissive temperature, revealed differences between secA and secY mutants. In the secAts mutant the great majority of cytoplasmic pre-TonA was not apparently processed to the mature form, whereas in the secYts mutant significant amounts of precursors were rapidly chased into mature TonA, which appeared in the outer membrane. These results suggest that SecA and SecY may act sequentially in the export of proteins to the outer membrane. In particular these data indicate that SecA is required to maintain pre-TonA in a translocationally competent form prior to interaction with the SecY export site.

Bacterial Outer Membrane Proteins↗
PubMed1987

Release of a chimeric protein into the medium from Escherichia coli using the C-terminal secretion signal of haemolysin.

Recently, we have identified a novel topogenic sequence at the C terminus of Escherichia coli haemolysin (HlyA) which is essential for its efficient secretion into the medium. This discovery has introduced the possibility of using this secretion system for the release of chimeric proteins from E. coli directly into the medium. We have now successfully fused this C-terminal signal to a hybrid protein containing a few residues of beta-galactosidase and the majority of the E. coli outer membrane porin OmpF lacking its own N-terminal signal sequence. We find that this chimeric protein is specifically translocated across the inner and outer membranes and is released into the medium. In addition, we have further localized the HlyA secretion signal to the final 113 amino acids of the C terminus. In fact, a specific secretion signal appears to reside at least in part within the last 27 amino acids of HlyA.

Amino Acid Sequence↗
PubMed1986

Abnormal steroid excretion in gestational trophoblastic disease complicated by ovarian theca-lutein cysts.

Serum and urine steroids were examined in two subjects with trophoblastic disease accompanied by large ovarian theca-lutein cysts and compared with those from 10 patients with trophoblastic disease but without palpable cysts. In the patients without cysts normal values were obtained for serum oestradiol, progesterone, 17 alpha-hydroxyprogesterone and androstenedione, and for urinary total oestrogens, pregnanediol, pregnanetriol, and 17-oxosteroids. Nineteen urinary steroid metabolites, quantified by capillary gas-liquid chromatography, were either within reference limits or marginally raised. In several cases relatively minor increases in serum testosterone and cortisol and urinary free cortisol were observed. In contrast, the subjects with cysts showed pronounced excesses of androgen metabolites, 17 alpha-hydroxypregnenolone, pregnanediol, and pregnanetriol, and both exhibited a similar pattern of unusual additional metabolites. The profiles superficially resembled those seen in 21-hydroxylase deficiency adrenogenital syndrome, but there were important discrepancies reflecting known differences in ovarian and adrenal steroid metabolism. Chemotherapy led to decline of human chorionic gonadotrophin concentrations, regression of the cysts, and return to normal of the steroid profile. Excess steroids in the patients with cysts may have originated in the ovary rather than in the trophoblastic tissue.

Adult↗
PubMed1986

Group meetings for parents and spouses of bone marrow transplant patients.

To reduce the stress and social isolation of being the parent or spouse of a patient hospitalized for bone marrow transplantation (BMT), a support group for family members was established. Sharing the common experience of the BMT procedure was valuable to family members despite differences in patient's age or disease, relationship to the patient, or socio-economic status. Recommendations are made to include similar groups in planning to meet the psychosocial needs of family members at other centers where patients are treated with high-risk, high intensity procedures.

Adolescent↗