The proregion of papaya proteinase IV inhibits Colorado potato beetle digestive cysteine proteinases

Three distinct digestive protease systems were induced in larvae of the herbivorous pest, Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), and used as a model to assess the ability of the proregion of papaya proteinase IV (PPIV; glycyl endopeptidase, EC 3.4.22.25) to act as an inhibitor of insect digestive cysteine proteinases. As shown by gelatin/PAGE and complementary inhibition assays, a recombinant form of the proregion produced in Escherichia coli inhibited a fraction of the insect proteases also inhibited by the well-characterized inhibitor of cysteine proteinases, oryzacystatin I (OCI). In contrast with OCI, the inhibitory potency of the proregion was affected by an increase of the temperature, suggesting a certain alteration of its structural integrity by the insect non-target proteases. This apparent susceptibility to proteolysis was confirmed by SDS-PAGE, after challenging the proregion with the different insect extracts. As seen on gel, selective inhibition of the insect aspartate proteinase, cathepsin D, with the inhibitor pepstatin A preserved the activity of the proregion against cysteine proteinases by preventing its hydrolysis. Taken together, these observations suggest the potential of plant protease proregions as regulators of cysteine proteinases in biotechnological systems, and show the ability of protease inhibitors to preserve the integrity of 'companion' defense-related proteins from the action of insensitive proteases in target pests.

Cognitive deficits, psychopathology, and psychosocial functioning in bipolar mood disorder

The objective of this study was to study the relationship of poor functioning, cognition, and psychopathology in bipolar mood disorder. The authors assessed 36 patients with bipolar mood disorder (23 VA, 13 community) for the presence of psychopathology, cognitive deficits, and psychosocial impairment. The authors assessed psychopathology using screening and follow-up questions based on the schedule for affective disorder and schizophrenia, lifetime version (SADS-L), schedule for the assessment for negative symptoms (SANS), and schedule for the assessment of positive symptoms (SAPS), and psychosensory features using the "Profile of Psychomotor Symptoms." They tested cognitive functioning in the following domains: 1) general intelligence and language, 2) verbal and visual memory, and 3) visuospatial functioning. They also assessed psychosocial functioning using a structured scale to assess maladjustment and an impairment rating scale. Patients with bipolar disorder showed significant impairment compared to age equivalent normals in several cognitive domains. Anhedonia was related to memory deficits. Memory deficits were also associated with poor psychosocial functioning. This study demonstrates that nondemented, asymptomatic patients with bipolar disorder exhibit substantial cognitive deficits that are associated with poor functioning, and anhedonia and avolition best predict this outcome.

The isolation of genomic DNA from blackcurrant (Ribes nigrum L.)

A method is described for isolating DNA of high molecular mass (M(r)) from blackcurrant and other softfruit species. Following a hexacethylytimethyl ammonium bromide (CTAB)-based extraction procedure, samples are treated with a glycosidic hydrolase mixture and RNase, and then purified. The suitability of this DNA for Southern analysis and genomic-library construction is demonstrated.

The sensitization hypothesis and importance of psychosensory features in mood disorder: a review

The sensitization model of mood disorders, articulated 10 years ago, predicts symptoms, course, and treatment response relationships. However, clinical data testing this model have not been reviewed. The authors reviewed all English-language publications characterizing psychosensory features (clinical phenomena hypothesized to reflect temporolimbic sensitization) and the relationship of these features to mood disorder, course, and treatment. They found that 20% to 80% of bipolar and 80% of epileptic patients experience psychosensory phenomena. Although these features do not identify a specific subgroup of mood disorders, their prevalence is highest in schizoaffective bipolar patients. The value of psychosensory features in predicting treatment response or chronicity is unclear.

cDNA cloning and characterisation of an alpha-glucosidase gene from potato (Solanum tuberosum L.)

Using an Arabidopsis thaliana expressed sequence tag with sequence similarity to human lysosomal alpha-glucosidase as a probe, a potato cDNA was isolated. The cDNA encodes a polypeptide with an Mr value of 105,400 and the most significant matches of the deduced amino acid sequence are with members of family 31 of glucosyl transferase. The potato cDNA was expressed in a strain of Saccharomyces cerevisiae that is deficient in maltase activity and unable to grow using maltose as a carbon source (ABYSMAL81). Expression of the potato cDNA in the mutant yeast strain restores its ability to use maltose as a carbon source for growth. Additionally, alpha-glucosidase activity could be measured in extracts of the yeast cells following complementation. A range of maltodextrins were substrates for this activity. The steady-state expression level of the potato alpha-glucosidase gene was low in most tissues examined, the highest levels occurring in sprouting tubers and source leaves.

The isolation of RNA from raspberry (Rubus idaeus) fruit

Previous attempts to extract high-quality, total RNA from raspberry (Rubus idaeus) fruits using published protocols have proven to be unsuccessful. Even the use of protocols developed for the extraction of RNA from other fruit tissue has resulted in low yields (1) or the isolation of degraded RNA (2). Here, we report on the development of a quick and simple method of extracting total RNA from raspberry fruit. Using this method, high yields of good quality, undegraded RNA were obtained from fruit at all stages of ripening. The RNA is of sufficient quality for northern analysis and cDNA library construction.

Trypsin isolated from the midgut of the tobacco hornworm, Manduca sexta, is inhibited by synthetic pro-peptides in vitro

The seven residue synthetic peptides VPAYPQR and VPANPQR, identical to the pro-regions of midgut trypsins from Manduca sexta, inhibit the peptidase activity of the mature enzymes. The inhibitory potencies of these peptides towards purified insect trypsin were determined and were found to be more potent at pH 7.0 than at pH 10.0. These peptides did not inhibit porcine trypsin, nor were they degraded rapidly by purified insect trypsin. We suggest that these particular peptides, and insect proregions in general, may be suitable for use in genetically engineered plants as insect specific inhibitors of digestive proteases.

Differences in the prevalence of psychosensory features among schizophrenic, schizoaffective, and manic patients

The purpose of the study was to test the sensitization model for mood disorder by comparing the prevalence of psychosensory features in bipolar, schizoaffective-manic, and schizophrenic patients. We evaluated 66 patients (13 schizophrenics, 13 schizoaffective bipolar types, and 40 bipolars) for the presence of psychosensory features and psychopathology. Schizoaffective manics had the highest prevalence of recent (F = 6.9(2,32), P = < .001) and past (F = 3.7(2,32), P = < .05) psychosensory features. We conclude that psychosensory features are markers of severity of affective rather than nonaffective psychosis.

Evaluation and management of attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder is the most common pediatric psychiatric disorder, involving one of every 20 children. It is often a disabling condition and is frequently accompanied by high levels of frustration and comorbidity. Diagnosis of attention-deficit hyperactivity disorder requires a detailed history from the family and use of rating scales to collect observations from two or more settings. Effective treatment, including behavior management, appropriate educational placement and stimulant medication, will improve academic performance and behavior in most patients. Armed with an organized approach and a broad general knowledge of stimulant therapy, the family physician can effectively evaluate and coordinate the initial therapy for many of these troubled children within the office setting. Children in whom initial management fails or for whom the diagnosis is unclear or complicated should be referred to appropriate mental health professionals.

Isolation of RNA from blackcurrant (Ribes nigrum L.) fruit

Extraction of high-quality RNA from blackcurrant fruit has hitherto proved difficult, probably owing to high levels of phenolic and polysaccharide components in the berries. The procedure described here is a modification of one described for grape berries, and yields RNA suitable for in vitro translations, RNA blot analysis, and cDNA library construction.

The prosequence of procaricain forms an alpha-helical domain that prevents access to the substrate-binding cleft

BACKGROUND

Cysteine proteases are involved in a variety of cellular processes including cartilage degradation in arthritis, the progression of Alzheimer's disease and cancer invasion: these enzymes are therefore of immense biological importance. Caricain is the most basic of the cysteine proteases found in the latex of Carica papaya. It is a member of the papain superfamily and is homologous to other plant and animal cysteine proteases. Caricain is naturally expressed as an inactive zymogen called procaricain. The inactive form of the protease contains an inhibitory proregion which consists of an additional 106 N-terminal amino acids; the proregion is removed upon activation.

RESULTS

The crystal structure of procaricain has been refined to 3.2 A resolution; the final model consists of three non-crystallographically related molecules. The proregion of caricain forms a separate globular domain which binds to the C-terminal domain of mature caricain. The proregion also contains an extended polypeptide chain which runs through the substrate-binding cleft, in the opposite direction to that of the substrate, and connects to the N terminus of the mature region. The mature region does not undergo any conformational change on activation.

CONCLUSIONS

We conclude that the rate-limiting step in the in vitro activation of procaricain is the dissociation of the prodomain, which is then followed by proteolytic cleavage of the extended polypeptide chain of the proregion. The prodomain provides a stable scaffold which may facilitate the folding of the C-terminal lobe of procaricain.

Crystal structure of a caricain D158E mutant in complex with E-64

The structure of the D158E mutant of caricain (previously known as papaya protease omega) in complex with E-64 has been determined at 2.0 A resolution (overall R factor 19.3%). The structure reveals that the substituted glutamate makes the same pattern of hydrogen bonds as the aspartate in native caricain. This was not anticipated since in the native structure there is insufficient room to accommodate the glutamate side chain. The glutamate is accommodated in the mutant by a local expansion of the structure demonstrating that small structural changes are responsible for the change in activity.

Autocatalytic processing of pro-papaya proteinase IV is prevented by crowding of the active-site cleft

The DNA coding for pro-papaya proteinase IV (PPIV) has been cloned and expressed in Escherichia coli. Heterologous expression of the protein, followed by refolding in vitro, yields an enzymatically active pro-enzyme which fails to autodigest to form the mature protein. Mutagenesis of the active site of papain to simulate that of PPIV yields a proenzyme which also fails to autoactivate. Complementary mutagenesis of the pro-region/mature boundary of PPIV, to introduce its own substrate recognition sequence, has, however, produced a pro-enzyme that will autocatalytically cleave. This is the first report of enzymatic activity in a recombinant pro-cysteine proteinase, and the first time that such a protein has been shown to fail to autocatalytically cleave because of its stringent substrate specificity.

Brace-free rehabilitation, with early return to activity, for knees reconstructed with a double-looped semitendinosus and gracilis graft

Forty-one patients in whom operative reconstruction of a torn anterior cruciate ligament had been performed by one surgeon with use of a double-looped semitendinosus and gracilis hamstring graft were studied to determine (1) if a brace-free rehabilitation program compromised the early stability of the knee; (2) if the stability of the knee deteriorated between four months, when the patient returned to unrestricted activities, and two years; and (3) if the function of the treated knee was completely restored by four months after the operation. The graft was placed arthroscopically, without impingement by the intercondylar roof, and was fixed within the tibial tunnel to conserve the length of the graft. The stability and function of thirty-seven of the knees were assessed at four months as part of a larger prospective study. Four patients chose not to return for the four-month evaluation. The patients returned to unrestricted sports and work activities after the four-month evaluation. At two years, all forty-one patients were evaluated. At four months, after completion of the brace-free rehabilitation program, thirty-three (82 per cent) of the thirty-seven patients had an absent pivot shift and a normal Lachman test. Twenty-eight (88 per cent) of thirty-four knees had less than three millimeters of difference in laxity compared with the contralateral knee, as determined by testing at the maximum manual force with use of a KT-1000 arthrometer. Stability remained unchanged at two years, justifying the early return to vigorous activities at four months. The girth of the thigh, the extension of the knee, and the Lysholm and Gillquist score were the same at four months as at two years, verifying the success of the brace-free intensive rehabilitation program in the restoration of early function to the treated knee. However, some continued improvement was observed in the performance of the one-leg-hop for distance test between four months and two years.

Formal thought disorder in schizophrenia. Linguistic, attentional, and intellectual correlates

Formal thought disorder (i.e., abnormal utterances and communication problems) is a prominent feature of schizophrenia. To investigate the hypothesis that formal thought disorder in schizophrenics represents a disturbance of language functioning, we compared 21 thought-disordered and 16 non-thought-disordered schizophrenics on the Porch Index of Communicative Ability. The thought-disordered schizophrenics were significantly more impaired. We also examined nonlinguistic factors potentially impacting language performance in schizophrenics (e.g., disturbed attention, intellect, and/or thought content). Reduced attention was the best predictor of language performance in the thought-disordered group, whereas low intellect and reduced attention were predictive of language dysfunction in the non-thought-disordered group. Disturbed thought content was not predictive of language impairment in either group. These findings provide partial support for the idea that formal thought disorder in schizophrenics represents defective language functioning.

Decline of U.S. medical student career choice of psychiatry and what to do about it

OBJECTIVE

In 1994, only 3.2% of U.S. medical school graduates chose psychiatry, the lowest proportion since 1929. Success in recruiting such graduates is necessary to maintain adequate numbers of psychiatrists. The authors' goal was to gain an understanding of the determinants of specialty selection to ensure adequate recruitment.

METHOD

They reviewed all recruitment-related English-language publications since 1959: 173 papers, 17 reports, and 10 books.

RESULTS

They found that recruitment has been cyclical, with success from 1940 to 1969 and from 1985 to 1988, decline from 1970 to 1984 and from 1989 to 1994, and a possible small upswing in 1995. The 1940-1969 success began with 1) public recognition of a dramatic shortage of psychiatrists to serve in the military and treat casualties and 2) the fervor of the community mental health movement, which promised to prevent mental illness; massive resources were provided for psychiatry during this period. The declines were associated with 1) the failure of the community mental health movement to fulfill its promise, 2) psychiatry's becoming more biologically oriented and medically conventional, and 3) the effects of managed care and increased competition for patients. The psychiatry departments that have high recruitment rates are in public-supported schools, particularly in the South, or give considerable priority and resources for medical student psychiatric education.

CONCLUSIONS

A study of the psychiatric workforce is needed to ascertain whether there is a surplus or a shortage of psychiatrists. Regardless, to ensure adequate recruitment, medical institutions and departments of psychiatry must commit resources for student education in psychiatry.

Predictors of planned retirement age: an application of Beehr's model

Given the aging workforce, understanding the retirement process is an area of increasing interest to organizations. T. A. Beehr's (1986) model of retirement behavior was used in this study as a basis for selecting personal, psychological, and organizational predictors of subsequent planned retirement age. In addition, potential differences in predictors of the planned retirement age of retirement-eligible and retirement-ineligible respondents were explored. Two hundred sixty-four respondents working for a large multinational firm completed 2 surveys on their attitudes toward work and retirement. Results showed that chronological age, employee health, and self-perceptions of the ability to adjust to retirement predicted subsequent planned retirement age. Interactions of the predictors with retirement eligibility are reported along with implications for retirement-planning programs.

Correction of bone marrow nucleated cell counts for the presence of fat particles

Although the use of bone marrow transplantation has increased greatly in recent years, the quality control procedures used in bone marrow processing laboratories remain less than ideal. Accurate marrow total nucleated cell (TNC) counts are essential for effective monitoring of bone marrow collection and processing. Aspirated marrow is variably contaminated by fat particles, resulting in overestimation of marrow TNC by automated analyzers. A recently-marketed hematological analyzer (Cobas-Helios; Roche Diagnostic Systems, Branchburg, NJ) offers the potential to correct marrow TNC counts for fat particles using available software. The authors investigated the accuracy of corrected TNC counts on 21 marrow samples, using a visual chamber count as the reference method. The correction methods studied were software correction, using the Cobas-Helios differential system, and replacement of the sample plasma with saline. Uncorrected automated marrow TNC counts (mean, 28.4 x 10(9)/L) were significantly higher than the visual reference counts (mean, 23.1 x 10(9)/L). Neither the mean corrected automated count (24.3 x 10(9)/L) nor the mean saline replaced count (24.6 x 10(9)/L) differed significantly from the mean visual reference count. For both the corrected automated and saline replaced counts, 20 of the 21 data points (95%) fell within a 95% confidence interval computed for the reference method. The authors conclude that both the corrected automated method, using the Cobas-Helios, and the saline replacement method are acceptable alternatives to the visual chamber count.