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Biomedical subjects

J Kay

Publications and source records attributed to J Kay.

At least 37 records · Page 2Linked to original sources
PubMed1999

Identification of eukaryotic parvulin homologues: a new subfamily of peptidylprolyl cis-trans isomerases.

We report here the existence of a subfamily of eukaryotic parvulin proteins that have strong sequence homology with E. coli parvulin, but lack the WW domain found in previously described eukarytoic parvulins. We hence term members of this subfamily EPVH (eukaryotic parvulin homologue). We describe the characterisation of hEPVH (human eukaryotic parvulin homologue). Immunogold labelling transmission electron microscopy reveals that hEPVH is preferentially localised in the mitochondrial matrix. The homology of hEPVH with its prokaryotic ancestor supports the hypothesis that this protein may have a mitochondrial function. An essential role in this organelle may explain the need for a high degree of conservation of this protein between distantly related species.

Amino Acid Sequence↗
PubMed1999

Processing, activity, and inhibition of recombinant cyprosin, an aspartic proteinase from cardoon (Cynara cardunculus).

The cDNA encoding the precursor of an aspartic proteinase from the flowers of the cardoon, Cynara cardunculus, was expressed in Pichia pastoris, and the recombinant, mature cyprosin that accumulated in the culture medium was purified and characterized. The resultant mixture of microheterogeneous forms was shown to consist of glycosylated heavy chains (34 or 32 kDa) plus associated light chains with molecular weights in the region of 14,000-18,000, resulting from excision of most, but not all, of the 104 residues contributed by the unique region known as the plant specific insert. SDS-polyacrylamide gel electrophoresis under non-reducing conditions indicated that disulfide bonding held the heavy and light chains together in the heterodimeric enzyme forms. In contrast, when a construct was expressed in which the nucleotides encoding the 104 residues of the plant specific insert were deleted, the inactive, unprocessed precursor form (procyprosin) accumulated, indicating that the plant-specific insert has a role in ensuring that the nascent polypeptide is folded properly and rendered capable of being activated to generate mature, active proteinase. Kinetic parameters were derived for the hydrolysis of a synthetic peptide substrate by wild-type, recombinant cyprosin at a variety of pH and temperature values and the subsite requirements of the enzyme were mapped using a systematic series of synthetic inhibitors. The significance is discussed of the susceptibility of cyprosin to inhibitors of human immunodeficiency virus proteinase and particularly of renin, some of which were found to have subnanomolar potencies against the plant enzyme.

Amino Acid Sequence↗
PubMed1999

Structural and functional analysis of the rat metallothionein III genomic locus.

Metallothionein III (MT III) has been reported to suppress neuronal growth in a rat in vitro model system. The protein and its specific mRNA are detected predominantly in the brain, differentiating MT III from the well-characterised archetypal metallothioneins. Isolation, sequencing and functional analysis of the rat MT III genomic locus indicated that, although the organisation of the gene was conserved between MT III and the more conventional metallothioneins, the 5' flanking region of the MT III gene was distinct. Within this region, a number of putative regulatory elements were identified, including the metal regulatory elements (MREs) characteristic of metallothionein promoters. However, despite their conservation in sequence with active elements, the MREs of MT III were unresponsive to zinc. A 'silencing element' was revealed within a 250 bp section of the MT III promoter which suppressed gene expression in two brain cell lines. The operation of this silencing region in conjunction with the inactive MREs may explain the distinct expression profile observed for MT III within the central nervous system and during neuronal development.

Animals↗
PubMed1999

Cathepsin D from the liver of the antarctic icefish Chionodraco hamatus exhibits unusual activity and stability at high temperatures1.

Cathepsin D was purified to homogeneity from the liver of Antarctic icefish by anion-exchange chromatography followed by affinity chromatography on concanavalin-A Sepharose. The purified enzyme showed a molecular mass of 40 kDa and displayed optimal activity at pH 3.0 with a synthetic chromogenic substrate. The N-terminal sequence of this proteinase was determined by automated Edman degradation and was used to design a primer for use in reverse-transcriptase polymerase chain reaction. The open reading frame of the cloned cDNA encoded an aspartic proteinase, which contained the experimentally determined N-terminal sequence. The predicted sequence (396 residues) had a high similarity with those of cathepsin D from various vertebrate sources, but was considerably different from that of nothepsin, a distinct aspartic proteinase described previously from Antarctic fish [1]. Determination of kinetic parameters for substrate hydrolysis showed that, at temperatures between 8 and 50 degrees C, the icefish cathepsin D had a higher specificity constant (kcat/Km) than human cathepsin D. The stability of both enzymes was measured at 50 degrees C and half-lives of 55 and 3 min were derived for icefish and human cathepsin D, respectively.

Amino Acid Sequence↗
PubMed1999

A distinct member of the aspartic proteinase gene family from the human malaria parasite Plasmodium falciparum.

A gene (hap) transcribed during the intra-erythrocytic life cycle stages of the human malaria parasite Plasmodium falciparum was cloned and sequenced. It was found to encode a protein belonging to the aspartic proteinase family but which carried replacements of catalytically crucial residues in the hallmark sequences contributing to the active site of this type of proteinase. Consideration is given as to whether this protein is the first known parasite equivalent of the pregnancy-associated glycoproteins that have been documented in ungulate mammals. Alternatively, it may be operative as a new type of proteinase with a distinct catalytic mechanism. In this event, since no counterpart is known to exist in humans, it affords an attractive potential target against which to develop new anti-malarial drugs.

Amino Acid Sequence↗
PubMed1999

Rectal indomethacin reduces postoperative pain and morphine use after cardiac surgery.

PURPOSE: To evaluate the combination of rectal indomethacin with patient controlled intravenous morphine analgesia (PCA) on postoperative pain relief and opioid use after cardiac surgery. METHODS: With institutional ethics approval, 57 consenting adults undergoing elective aortocoronary bypass surgery were randomly assigned preoperatively in a double-blind fashion to receive either placebo (n = 26) or indomethacin 100 mg suppositories (n = 31), 2-3 hr postoperatively, and 12 hr later. Both groups utilized PCA morphine. Pain scores in the two treatment groups were assessed on a 10-cm visual analogue scale (VAS) (at rest and with cough) at 4, 6, 12, 18 and 24 hr after initial dosing, and were analyzed through a 2 x 5 repeated measures of variance. The 24 hr analgesic consumption, 12 and 24 hr chest tube blood loss, and time to tracheal extubation were also recorded, and compared for the two treatment arms through Student's t test on independent samples. RESULTS: Postoperative morphine consumption in the first 24 hr was 38% less in the indomethacin group (22.40 +/- 12.55 mg) than the placebo group (35.99 +/- 25.84 mg), P = 0.019. Pain scores, measured with a VAS, were 26% to 66% lower in the indomethacin vs placebo group at rest (P = 0.006), but not with cough, for all times assessed. There was no difference in blood loss (at 12 hr) or time to tracheal extubation for both groups. CONCLUSION: The combination of indomethacin with morphine after cardiac surgery results in reduced postoperative pain scores and opioid use without an increase in side effects.

Administration, Rectal↗
PubMed1999

Empirically supported psychological and behavioral therapies in pediatric rehabilitation of TBI.

This article examines the empirical support for psychological therapies for children with traumatic brain injury (TBI). Empirical support for psychological treatments of noninjured children provides a foundation upon and a framework in which to discuss applications to children with neurobehavioral dysfunction. Behavioral interventions to address externalizing behaviors have received the greatest focus, whereas there is a paucity of work that pertains to internalizing features and prosocial behavior such as assertiveness. Although the systematic study of psychological intervention lags far behind the rapidly increasing knowledge of neurobehavioral sequelae to TBI, there are promising directions that stem from initial findings.

Aggression↗
PubMed1999

Effects of paroxetine on heart period variability in patients with panic disorder: a study of holter ECG records.

We investigated cardiac autonomic function in 16 patients with panic disorder before and after treatment with paroxetine using Holter ECG records. Our previous data suggest a relative increase in sympathetic activity in patients with panic disorder, especially during sleep. Data for 20 h and awake and sleep periods were analyzed using spectral analysis to quantify absolute and relative heart period variability in ultra low (ULF: <0.0033 Hz), very low (VLF: 0.0033-0.04 Hz), low (LF: 0.04-0.15 Hz) and high (HF: 0.15-0.5 Hz) frequency bands. We also obtained fractal dimensions (FD) for the 20-hour, awake and sleep time series of RR intervals. Paroxetine treatment (19.7 +/- 4.7 mg/day for 105 +/- 37 days) resulted in a significant improvement in the frequency and intensity of panic attacks and also on the state anxiety inventory. Paroxetine treatment produced a significant decrease of 20-hour absolute HF power, awake absolute LF power and sleep absolute HF power. There was also a significant decrease of FDs after treatment with paroxetine for the sleep period. The decrease in LF and HF powers, and sleep FD is likely due to the antimuscarinic effect of paroxetine. The decrease in day-time LF power may also be due to a decrease in relative cardiac sympathetic activity after paroxetine treatment.

Adult↗
PubMed1999

Temporal lobe epilepsy, temporal lobectomy, and major depression.

Sixty-two patients with medically intractable complex partial seizures who had either surgical or no surgical intervention were followed up at a mean of 10.9 years after surgery or initial evaluation. Of the 49 surgical patients, 45% had a life-time history of depression, versus 15% of the 13 patients in the nonsurgical comparison group. In the surgical group, 77% had prior history of depression; of these, 47% experienced no further episodes after surgery. Depression occurred de novo after lobectomy in 5 surgical patients (approximately 10%), 4 developing depression within 1 year. Presurgical presence of depressive episodes predicted continued postoperative depressive episodes. The significantly higher depression rate in patients with temporal lobe seizure foci suggests limbic system dysfunction in the increased risk for depression. Postsurgical resolution of episodes in almost 50% of these patients supports the tenet that depression per se is not a contraindication for surgery in patients with intractable seizures.

Adult↗
PubMed1999

Personality disorders among medically refractory epileptic patients.

DSM-III-R personality disorders were assessed in 52 medically refractory epileptic patients. Twenty-one percent of patients met threshold criteria for an Axis II disorder. Dependent and avoidant personality disorders were the most common diagnoses. Epileptic aura was positively correlated with the presence of personality disorders. These results support previous studies that have demonstrated an increased rate of dependency and social isolation in epileptic patients. This increase may be related to disrupted psychosocial functioning as a consequence of having epilepsy, to disrupted neuronal function in central nervous system structures as a consequence of repeated epileptiform discharge or to some combination of the two.

Adult↗
PubMed1999

Some neurobiological aspects of psychotherapy. A review.

Ever since the idea was accepted that memory is associated with alterations in synaptic strength, studies on the cellular and molecular mechanisms responsible for the plastic changes in neurons have attracted wide interest in the scientific community. This article explores the process of memory consolidation leading to persistent modifications in synaptic plasticity as a mechanism by which psychotherapy facilitates changes in the permanent storage of information acquired throughout the individual's life. The psychobiological interrelationships of affect, attachment, and memory offer a perspective regarding the etiology and treatment of clinical disturbances of affect. Analogies between brain physiology and modes of psychotherapy provide the foundation for a review of psychiatric disorders involving the inability to control fear, obsessions, compulsions, and delusions, all of which respond to psychotherapeutic interventions.

Affect↗
PubMed1999

Reducing AIDS risk among inner-city women: a review of the Collectivist Empowerment AIDS Prevention (CE-AP) Program.

We discuss the process underlying our HIV-prevention project for young inner-city women. Health interventions are almost uniformly based on individualistic models of health and behavior. In contrast, AIDS and AIDS prevention, by their very social nature, may require more collectivist principles of disease, health, and intervention. We conducted a behavioral intervention, the Collectivist Empowerment AIDS Prevention (CE-AP) Program, with young, inner-city women to deal with this critical health issue. Our primary intervention goal was to promote women's sense of owning and making healthy choices about their bodies. We attempted to accomplish this by emphasizing the concepts of empowerment, collectivism (as opposed to individualism), and culturally sensitive skill building. Collectivism is emphasized to encourage women to involve others in their behavioral health decisions and to gain power through social joining and coalition building. A woman's behavioral decisions affect many others in her life. Thus, involving others in decision making emphasizes the connection between an individual's actions and their impact on interpersonal relationships. CE-AP was found to be effective in changing safer-sex behavior and we review our findings and future directions.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Active site mutants of human herpesvirus-6 proteinase.

Amino acid residues thought to comprise the catalytic triad of HHV-6 proteinase were changed by site-directed mutagenesis in the precursor form of the proteinase. By monitoring the ability of each mutant proteinase precursor to undergo autoprocessing, Ser116, His46 and His135 were identified as catalytically crucial. An attempt was made to mimic the catalytic triad arrangement of archetypal serine proteinases by replacement of the second histidine, His135, by an Asp. Instead of increasing the autoprocessing ability of the His135Asp mutant HHV-6 proteinase precursor, this mutation had a detrimental effect since the precursor persisted predominantly in its unprocessed form.

Base Sequence↗
PubMed1998

Napsins: new human aspartic proteinases. Distinction between two closely related genes.

cDNA sequences were elucidated for two closely related human genes which encode the precursors of two hitherto unknown aspartic proteinases. The (pro)napsin A gene is expressed predominantly in lung and kidney and its translation product is predicted to be a fully functional, glycosylated aspartic proteinase (precursor) containing an RGD motif and an additional 18 residues at its C-terminus. The (pro)napsin B gene is transcribed exclusively in cells related to the immune system but lacks an in-frame stop codon and contains a number of polymorphisms, one of which replaces a catalytically crucial Gly residue with an Arg. Consideration is given to whether (pro)napsin B may be a transcribed pseudogene or whether its putative protein product undergoes rapid intracellular degradation.

Amino Acid Sequence↗