PubMed Health⌕ Search

Biomedical subjects

R A Novak

Publications and source records attributed to R A Novak.

11 recordsLinked to original sources
PubMed1987

Do periodic hyperinflations improve gas exchange in patients with hypoxemic respiratory failure?

Prolonged artificial ventilation may result in worsening gas exchange and pulmonary compliance in patients with otherwise normal lungs. Prolonged hyperinflations to 40 cm H2O can completely reverse deterioration of gas exchange and compliance in such patients. Similar efforts have effectively recruited atelectatic lung regions in critically ill patients. Less aggressive hyperinflations have not improved lung function in patients with abnormal lungs with hypoxemia. However, sustained exaggerated hyperinflations may successfully open collapsed lung units in these patients when standard recruitment techniques fail. We compared periodic hyperinflations of 40 cm H2O lasting 15 to 30 sec associated with body positioning (directed recruitment [DR]) to standard bag-sigh-suctioning (BSS) for their effects on gas exchange and pulmonary compliance in 16 stable surgical ICU patients with hypoxemic respiratory failure of 24-h duration or longer. Patients were sequentially alternated between DR and BSS (group 1, BSS followed by DR; group 2, DR followed by BSS). Neither technique, alone or in sequence, resulted in a sustained (greater than or equal to 5 min) improvement or deterioration in either gas exchange or pulmonary compliance. We conclude that neither BSS nor DR reliably affects gas exchange or compliance in patients with established hypoxemic respiratory failure.

Blood Gas Analysis↗
PubMed1978

Specific glycine uptake by identified neurons of Aplysia californica. II. Biochemistry.

Glycine is taken up twice as rapidly by neurons R3-R14 as by other identified neurons in the Aplysia parietovisceral ganglion. Earlier studies had shown that R3-R14 have much higher glycine concentrations than other Aplysia neurons. Most of the glycine taken up by R3-R14 was biochemically untransformed for at least 1 h following its uptake. Glycine is actively transported into into R3-R14 and other Aplysia neurons by carrier-mediated processes. Glycine uptake by R3-R14 was markedly reduced in the absence of Na+ and in the presence of Hg2+, while these treatments had little effect on glycine uptake by other Aplysia neurons. There appears to be a special glycine uptake system present in R3-R14 and a general glycine uptake system common to all Aplysia neurons. The elevated glycine concentrations and special glycine uptake associated with R3-R14 may indicate that glycine is utilized as a neurotransmitter by those neurons.

Alanine↗
PubMed1976

Abnormal ultrastructural changes in sodium periodate-stimulated lymphocytes from patients with chronic lymphocytic leukemia.

Lymphocytoid and plasmacytoid blasts have been identified in both normal and chronic lymphocytic leukemia lymphocyte cultures exposed to NaIO4. However, the appearance of ultrastructurally abnormal blasts in chronic lymphocytic leukemia cultures suggests that NaIO4 also stimulates the transformation of an abnormal subpopulation of lymphocytes. Development of invaginated nuclei produced morphological features similar to nuclear blebs, a cellular abnormally described in blood cells from other cancers. Furthermore, the consistent localization of nuclear invagination only to portions of nuclei adjacent to developing cytoplasmic microtublar complexes suggests a role for microtubules in the transformation process. The absence of these unusual blasts in cultures stimulated with other mitogens may indicate that these NaIO4-sensitive cells are not responsive to the more commonly used plant lectins.

Cell Nucleus↗
PubMed1976

L-fucose metabolism in cystic fibrosis fibroblasts.

The capacity of skin fibroblasts from cystic fibrosis (CF) and non-CF individuals to incorporate exogenous L-fucose into various metabolic pools was compared. Incorporation into intracellular acid-soluble pools and extracellular glycopeptides was measured by a dual-label co-chromatographic technique, whereas total macromolecular incorporation was measured by a single-label procedure. Although CF and normal fibroblasts incorporate exogenous fucose into intracellular acid-soluble and high molecular weight compounds in a similar manner, CF cells appear to be characterized by an increased incorporation of label into low molecular weight extracellular glycopeptides.

Chromatography↗
PubMedDate not supplied

Energy cost of walking in low lumbar myelomeningocele.

The aim of this study was to determine whether it is more efficient for adolescents with low lumbar myelomeningocele (MM) to walk with a reciprocal or a swing-through gait pattern. Energy measurements for subjects with MM were compared for reciprocal and swing-through gait and also with an able-bodied control group. The rate of oxygen consumption (in milliliters per kilogram per minute) was higher for both the reciprocal and swing-through conditions compared with the control group, but there was no difference in the rate of consumption between the two modes of walking. Walking velocities (in meters per minute) were slower for both the reciprocal and swing-through conditions compared with the control group, with reciprocal walking significantly slower than swing-through gait. Oxygen cost (in milliliters per kilogram per meter) was higher for both the reciprocal and the swing-through conditions compared with the control group. Oxygen cost was higher for reciprocal walking than for swing-through gait. Swing-through gait proved to be the more efficient walking pattern in this group of subjects with MM.

Adolescent↗