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Biomedical subjects

J Kay

Publications and source records attributed to J Kay.

At least 253 records · Page 14Linked to original sources
PubMed1983

A comparison of the accumulation and protein binding of environmental cadmium in the gills, kidney and liver of rainbow trout (Salmo gairdneri Richardson).

Rainbow trout were exposed to cadmium in their aquarium water for different lengths of time and at different concentrations. More than 99% of the total body loads accumulated under all such conditions of exposure was found in the liver, kidney and gills. Comparison of the metal-binding proteins in these organs indicated that two low mol. wt proteins sequestered the cadmium while zinc was bound to metallothionein. Cadmium was not found in association with metallothionein unless artificially high concentrations were introduced either by intraperitoneal injection of the fish or by dialysis of tissue extracts in vitro.

Animals↗
PubMed1983

Hematologic and immunologic abnormalities in anorexia nervosa.

Anorexia nervosa has been associated with various hematologic and immunologic abnormalities, including characteristic bone marrow changes, red cell acanthocytosis, leukopenia, complement deficiencies, and defective bactericidal activity of granulocytes. Dietary and psychogenic factors may play a role in these abnormalities, which are readily reversible after resolution of the underlying anorectic state. Although clinical data are conflicting, anorectic patients may have an increased susceptibility to infection.

Acanthocytes↗
PubMed1983

Pepsinogen in gastric carcinoma cells.

Immunoperoxidase staining of 125 gastric carcinomas showed pepsinogen in tumour cells of seven (5.6%) cases. Carcinomas from other sites were negative. The phenomenon is probably too uncommon to be useful in identifying secondary carcinomas as gastric in origin, but it is of some biological interest.

Adenocarcinoma↗
PubMed1982

Activation of spin-labeled chicken pepsinogen.

Chicken pepsinogen has been spin-labeled by the attachment of four nitroxides to epsilon-amino groups near the protein's amino terminus. Acidification results in a bond cleavage, generating a nonlabeled, enzymatically active protein. Electron spin resonance spectra of the spin-labeled zymogen, acidified in the presence or absence of pepstatin, are identical and indicate that the nitroxides are quite mobile, compared to the nonacidified zymogen. This mobilization is interpreted as the freeing of the peptide to which the spin-labels are attached, from the protein, subsequent to the acidification that causes a peptide bond cleavage. The rate at which the peptide leaves the protein is 1 order of magnitude slower than the cleavage of the peptide bond, measured by the rate of appearance of milk-clotting activity (first-order rate constants of 0.3 min-1 vs. 6 min-1 at pH 2, 22 degrees C). The inclusion of pepstatin, at molar ratios above 2 during activation, decreases the rate of peptide leaving. These observations, and those previously reported for activation of spin-labeled pig pepsinogen, are incorporated into a model of pepsinogen activation.

Amino Acid Sequence↗
PubMed1982

The effects of lactoyl-pepstatin and the pepsin inhibitor peptide on pig cathepsin D.

Lactoyl-pepstatin (an acylated tetrapeptide) is much more readily soluble in aqueous media than the more common isovaleryl- and acetyl-pepstatins (acylated pentapeptides). However, the K1 value for inhibition of cathepsin D by lactoyl-pepstatin at pH 3.5 is approx. 10(-7) M, some two to three orders of magnitude weaker than has been obtained previously for isovaleryl- or acetyl-pepstatins. One of the peptides released during activation of pig pepsinogen is known to be an effective inhibitor of pig pepsin, but it does not alter the activity of the similar aspartic proteinase, pig cathepsin D.

Animals↗
PubMed1982

Lipase-induced alterations of fatty acid synthesis by subcellular fractions from germinating pea (Pisum sativum L.).

1. The effect of exogenous lipases on fatty acid synthesis from [14C]malonyl-CoA by the microsomal and soluble fractions from germinating peas was studied. 2. Addition of phospholipase A2 or the lipase from Rhizopus arrhizus had no effect on total fatty acid synthesis by the soluble fraction but caused severe inhibition of that by the microsomal fraction. 3. The addition of enzymes with phospholipase activity particularly inhibited the microsomal stearate elongase. 4. Control studies indicated that the phospholipase-induced inhibition of fatty acid synthesis was due to the location of fatty acid synthetase, palmitate elongase and stearate elongase on the outside of the microsomal vesicles. 5. Experiments with a trypsin-like proteinase showed that approximately half the microsomal fatty acid synthesis was resistant to proteolysis. 6. Although addition of exogenous phospholipases had no effect on total fatty acid synthesis by the soluble fraction, it did increase alpha-hydroxylation of newly-formed palmitate and stearate. 7. The results provide further evidence for differences between the soluble and particulate fatty acid synthetase and palmitate elongase activities of germinating pea.

Fabaceae↗
PubMed1982

Degradation of smooth-muscle myosin by trypsin-like serine proteinases.

1. Hydrolysis of the myosins from smooth and from skeletal muscle by a rat trypsin-like serine proteinase and by bovine trypsin at pH 7 is compared. 2. Proteolysis of the heavy chains of both myosins by the rat enzyme proceeds at rates approx. 20 times faster than those obtained with bovine trypsin. Whereas cleavage of skeletal-muscle myosin heavy chain by both enzymes results in the generation of conventional products i.e. heavy meromyosin and light meromyosin, the heavy chain of smooth-muscle myosin is degraded into a fragment of mol. wt. 150000. This is dissimilar from heavy meromyosin and cannot be converted into heavy meromyosin. It is shown that proteolysis of the heavy chain takes place in the head region. 3. The 'regulatory' light chain (20kDa) of smooth-muscle myosin is degraded very rapidly by the rat proteinase. 4. The ability of smooth-muscle myosin to have its ATPase activity activated by actin in the presence of a crude tropomyosin fraction on introduction of Ca2+ is diminished progressively during exposure to the rat proteinase. The rate of loss of the Ca2+-activated actomyosin ATPase activity is very similar to the rate observed for proteolysis of the heavy chain and 3-4 times slower than the rate of removal of the so-called 'regulatory' light chain. 5. The significance of these findings in terms of the functional organization of the smooth muscle myosin molecule is discussed. 6. Since the degraded myosin obtained after exposure to very small amounts of the rat proteinase is no longer able to respond to Ca2+, i.e. the functional activity of the molecule has been removed, the implications of a similar type of proteolysis operating in vivo are considered for myofibrillar protein turnover in general, but particularly with regard to the initiation of myosin degradation, which is known to take place outside the lysosome (i.e. at neutral pH).

Adenosine Triphosphatases↗
PubMed1982

Degradation of myofibrillar proteins by trypsin-like serine proteinases.

The effects of the Ca2+-activated cysteine proteinase, the rat trypsin-like serine proteinase and bovine trypsin on myofibrillar proteins from rabbit skeletal muscle are compared. 2. Myofibrils that had been treated at neutral pH with the Ca2+-dependent proteinase and with the rat enzyme were (a) analyzed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and (b) examined in the electron microscope. Treatment with each proteinase resulted in the loss of the Z-discs, but the rat enzyme caused much more extensive disruption of the ultrastructure and degraded more of the myofibrillar proteins. 3. Purified F-actin was almost totally resistant to the proteinases, whereas G-actin was degraded by the rat trypsin-like proteinase at a rate approx. 15 times faster than was obtained with bovine trypsin. 4. Similar results were obtained with alpha-actinin, whereas tropomyosin was degraded more readily by bovine trypsin than by the rat trypsin-like proteinase. 5. The implications of these findings for the non-lysosomal breakdown of myofibrillar proteins in vivo are considered.

Animals↗
PubMed1981

When psychiatric residents treat medical students. Passage through idealization and overidentification.

The author describes a survey of psychiatric residents and faculty supervisors inquiring as to problematic aspects of the psychotherapy of medical students when treated by residents. Medical students' idealization of and identification with their resident-therapist were found to produce a significant amount of discomfort for the trainee. Difficulties in the psychotherapies were also attributed to the numerous possibilities of identification by the residents with their medical student patients. The varied forms of identification are detailed through the use of clinical vignettes submitted by respondents. It is the author's contention that psychotherapies involving these "special patients" provide a window for examining many issues in the development of the resident's professional self. Given the increasing number of medical students electing some form of personal psychotherapy and the declining number entering psychiatry residency training, the timeliness of this issue is noted.

Adult↗
PubMed1981

Proteolysis of myofibrillar proteins at neutral pH.

Myofibrils that had been exposed to rat pancreatic trypsin-like serine proteinase and to beef heart Ca2+-activated thiol proteinase were examined in the electron microscope and by SDS-gel electrophoresis. The former enzyme caused more extensive disruption of the ultrastructure and degraded more of the myofibril proteins than the CA2+-activated proteinase. The susceptibilities of individual purified proteins to the two enzymes were also compared. Myosin was virtually resistant to the Ca2+-activated enzyme but with smooth muscle myosin/rat serine proteinase at a ratio of 20000/1, heavy chain degradation took place very rapidly and the ability of the degraded myosin to have its ATPase activity activated by actin in the presence of Ca2+ was lost at a similar rate. G-actin, troponins T and I and alpha-actinin were also degraded readily by the trypsin-like proteinase whereas tropomyosin, a negatively charged rodlike protein, was more resistant. The cellular location of both proteinases remains to be established but from these results obtained in vitro, consideration is given to whether these types of proteinase might work cooperatively in vivo to bring about the disassembly and turnover of myofibrillar proteins that is known to take place outside the lysosomes in muscle.

Actins↗
PubMed1981

The independent psychiatry project: a model exercise in student learning.

The author describes a component of a freshman psychiatry course in which students are permitted in lieu of final examinations to pursue independent study in any aspect of the human life cycle. Examination of student topics over a three-year period revealed that many chose areas of study relating to significant past personal experiences. These students were able to gain considerable cognitive mastery over highly charged and/or traumatic life events. A second distinct student group directed its inquiries to the developmental aspects of physicianhood. The independent psychiatry project appears to be a vehicle for promoting active, autonomous, and reflective learning in the preclinical curriculum.

Curriculum↗
PubMed1980

An evaluation of the clinical potential of a comprehensive model of human respiration in artificially ventilated patients.

1. We have investigated the feasibility of accurately simulating the respiratory function of artificially ventilated patients, using a computer model of the respiratory system. Twelve patients artificially ventilated after uncomplicated cardiac bypass surgery was studied. 2. The basic information required to simulate individual ventilated subjects was measured or derived. A program was written to enable key model parameters to be adjusted automatically to match model predictions to these clinical measurements. On completion of this matching procedure all the variables computed by the model were compared with patient values (measured or derived) and their accuracy was assessed. 3. The matching algorithm successfully optimized parameters of the model representing metabolic activity, tissue respiratory quotient, venous admixture, physiological dead space and total body bicarbonate to match measured values for oxygen consumption, carbon dioxide production, Pa, O2, PaCO2, and arterial HCO3- respectively. Other variables compared arise from the solution of equations within the model and correlation between model and patient values is generally good (r greater than 0.9). However, values of Pv-, O2 correlate less well (r = 0.85). Factors affecting the accuracy of patient simulation are discussed and some deficiencies analysed. 4. The creation of an accurate, steady-state representation of a patient by the model opens up the possibility of using it interactively as an aid to clinical management. Some possible future developments of the technique are discussed.

Blood↗