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Biomedical subjects

J DeGroot

Publications and source records attributed to J DeGroot.

34 records · Page 2Linked to original sources
PubMed1990

Children at risk: I. Risk factors and child symptomatology.

The authors compared 134 6- to 12-year-old children from a military psychiatric clinic with a control sample to determine the salience of various risk factors in predicting levels of child psychopathology. Parents provided demographic information and completed standardized questionnaires on themselves and their children, while children completed two self-report symptom inventories. Results indicated that all hypothesized risk factors mediated effects on child psychopathology, but the effects of various risk factors differed as a function of the rater and type of psychopathological construct being measured. Generally, parental psychopathology and life stress mediated the greatest effects on overall child symptoms levels. Furthermore, the clinical and community samples differed in the presence and extent of risk factors. Results indicate the need for caution in studies of child psychopathology using only clinical samples and may suggest the importance of therapies based on environmental manipulations for a substantial proportion of patients seeking child psychiatric assistance.

Child↗
PubMed1986

Magnetic resonance imaging of the midbrain in Parkinson's disease.

We have analyzed magnetic resonance images of the midbrain in patients with Parkinson's disease, and have found that there is a narrowing of the signal from the pars compacta of the substantia nigra relative to controls. The nature of the histological changes that may be responsible for this effect is discussed. Magnetic resonance imaging has the potential of becoming a useful diagnostic tool in the management of parkinsonism.

Aged↗
PubMed1984

Magnetic resonance imaging of the nasopharynx.

Thirty subjects with normal nasopharyngeal anatomy and 12 patients with a variety of abnormalities were examined with computed tomography (CT) and magnetic resonance imaging (MR), using a prototype 0.35-T superconducting system. A spin-echo technique, a repetition time (TR) of 2.0 sec., and echo times (TE) of 28 and 56 msec. were optimal for depiction of both normal and abnormal anatomy. MR was superior to CT for display of both superficial and deep nasopharyngeal soft tissues in all 30 normal subjects and 10 of the 12 abnormal patients, clearly differentiating mucosal and lymphoid tissue (adenoids, lingual and palatine tonsils) from the surrounding musculature. MR was also superior to CT in distinguishing tumor from soft tissues and more sensitive to carotid sheath adenopathy, permitting a more detailed evaluation of retropharyngeal and deep cervical nodal metastases in 2 cases. Bones, calcification, and subtle abnormalities at the base of the skull were shown better by CT. The specificity of MR and its ability to differentiate nodal metastases from reactive lymphadenopathy require further evaluation.

Adolescent↗
PubMed1981

The CT-topography of retrobulbar anesthesia. Anatomic-clinical correlation of complications and suggestion of a modified technique.

The anatomic relationship of an injection needle as traditionally placed in retrobulbar anesthesia to optic nerve, orbital vessels and eye muscles is demonstrated by computed tomography. The clinical complications of retrobulbar injections are reviewed and correlated to the orbital topography in different positions of gaze, as analyzed in anatomic sections and CT images. The results indicate that with the transitional technique of retrobulbar injection the most important orbital structures are in the immediate neighbourhood of the needle. A different injection technique is discussed.

Anesthesia, Local↗
PubMed1980

Images of the optic nerve: anatomic-CT correlation.

The course of the intraorbital part of the optic nerve, as demonstrated on anatomic sections in various planes, is correlated with the appearance of the nerve in computed tomographic (CT) images. Discrepancies between the anatomic and CT appearance are analyzed and discussed. Since the optic nerve has a sinuous course in both the horizontal and vertical planes, no thin axial or sagittal section can be entirely parallel to the nerve. Any section will transsect the optic nerve obliquely, leading to an apparent hypodensity or "thinning" of certain segments as shown on CT. The appearance of the course of the nerve on reformatted CT images depends on the plane of the original CT section. Computed tomograms that are obtained with the eye in primary position do not allow reliable judgments regarding the course and size of the optic nerve.

Humans↗
PubMed1979

Lymphocyte blastogenic response to human thyroglobulin in Graves' disease, Hashimoto's thyroiditis, and metastatic thyroid cancer.

In view of the past contradictory reports concerning in vitro lymphocyte transformation induced by human thyroglobulin (Tg) in thyroid diseases, the present study was undertaken to re-examine the response using improved methods in cell separation, culture, and cell harvesting. It has been found that the optimal dose level of Tg for maximal blastogenesis in culture differs from patient to patient. Consequently, it is inappropriate to use a single dose level of Tg for evaluation of the blastogenesis in study groups. By using serial Tg dose levels of 0.5 through 30 micrograms/ml in cultures, it was found that that incidence of positive responders in Graves' disease was 69.2%, in Hashimoto's thyroiditis 71.4%, and in healthy controls 9.1%. Metastatic thyroid cancer patients responded in a 50% incidence. All of the positive responders in the cancer group had elevated Tg levels, but no anti-Tg antibody in their sera.

Adenocarcinoma↗
PubMed1973

Evaluation of new urinary tract infection screening devices.

Several new methods for detection of bacteriuria were studied to evaluate their usefulness as screening procedures. A new filter paper device incorporating dehydrated media and tetrazolium was found to be reliable when compared with the standard pour plate method in the laboratory and with the dip-slide method in a field test. It failed to detect yeasts and slowly growing streptococci. Antibiotics blocked the test when susceptible organisms were present. An agar-cup method was found to be quite reliable, but could be improved by use of differential media. The Griess test was confirmed in a small trial to be highly specific when used in conjunction with a first morning specimen, but of little value with random specimens. Phenzopyridine was found to give false positive reactions. The subnormal glucose test, although highly sensitive and specific, gave too many false positive tests to be useful other than as a screening method.

Agar↗
PubMedDate not supplied

Host-derived proteinases and degradation of dentine collagen in situ.

Dentine root caries is a process of demineralization and degradation of the organic matrix by proteinases. In this in situ study, the presence and activity of the matrix metalloproteinases 1, 2 and 9 (MMP-1, MMP-2, MMP-9) in saliva and in completely demineralized dentine specimens were investigated. Furthermore, the activity of cathepsin B was determined in saliva. A correlation between these enzymes and the level of degraded collagen was investigated. Demineralized dentine specimens were mounted in the partial prosthesis of 17 volunteers. Saliva samples were taken at 0, 2 and 4 weeks. After 4 weeks, the enzymes were extracted from the dentine specimens and the collagen loss was assessed. The collagen loss varied between 0 and 40.3%. Zymography of the saliva and the dentine extract samples showed that (pro-)MMP-2 and (pro-)MMP-9 were present. The levels of active MMPs were assessed, using fluorogenic MMP-specific substrates. All but 3 of the 51 saliva samples showed MMP-1 activity ranging from 1.5 to 101.1 relative fluorescence units (RFU)/s. Forty-eight saliva samples showed gelatinolytic MMP-2/MMP-9 activity (1.7-141.1 RFU/s). MMP-1 activity was shown in all dentine extracts varying between 3.5 and 295.0 RFU/s. From the dentine extracts, 15 showed MMP-2/MMP-9 activity (0.2-13.7 RFU/s). The MMP activity from both saliva and dentine extracts did not correlate with the collagen loss. The activity of salivary cathepsin B varied from 4.8 to 42.2 arbitrary units/min. A positive correlation was found between salivary MMP activity and cathepsin B activity. This study revealed that gelatinolytic enzyme activity was present both in saliva and dentine collagen. No correlation could be observed, however, between the level of enzyme activity and the collagen loss of the dentine specimens.

Aged↗
PubMedDate not supplied

Work and life: the end of the zero-sum game.

Most companies view work and personal life as competing priorities in a zero-sum game, in which a gain in one area means a loss in the other. From this traditional perspective, managers decide how their employees' work and personal lives should intersect and often view work-life programs as just so much social welfare. A new breed of managers, however, is trying a new tack, one in which managers and employees collaborate to achieve work and personal objectives to everyone's benefit. These managers are guided by three principles. The first is to clearly inform their employees about business priorities and to encourage them to be just as clear about personal priorities. The second is to recognize and support their employees as whole people, not only acknowledging but also celebrating their roles outside the office. The third is to continually experiment with the way work gets done, looking for approaches that enhance the organization's performance and allow employees to pursue personal goals. The managers who are acting on these principles have discovered that conflicts between work and personal priorities can actually be catalysts for identifying inefficiencies at the workplace. For example, one manager and his staff found a way to accommodate the increased workload at their 24-hour-a-day command center while granting the staff more concentrated time off. So far, these managers have usually been applying the principles without official sanction. But as the business impact of their approach becomes better appreciated, the authors predict, more and more companies will view these leaders as heralds of change.

Commerce↗
PubMedDate not supplied

Active MMPs captured by alpha 2 macroglobulin as a marker of disease activity in rheumatoid arthritis.

OBJECTIVE: The aim of the present study was to analyze alpha 2 Macroglobulin/MMP (alpha 2M/MMP) complex formation and to investigate whether MMP activity in alpha 2M/MMP complexes in serum can be used as a disease marker in rheumatoid arthritis (RA). METHODS: High and low molecular weight (H/LMW) substrates and inhibitors and size exclusion were used to analyze alpha 2M/MMP complex formation. LMW fluorogenic substrates were used to quantify the level of MMPs in alpha 2M/MMP complexes in the serum of RA patients and healthy controls. RESULTS: Active MMPs were fully inhibited by LMW inhibitor BB94 in the presence of alpha 2M, whereas no inhibition was achieved by HMW inhibitor TIMP-1. Size exclusion analysis showed alpha 2M/MMP complex formation in buffer and in normal plasma spiked with activated MMPs, which indicated alpha 2M/MMP complex formation in the systemic circulation. MMP activity in alpha 2M/MMP complexes in the serum of RA patients was significantly higher than in the serum of healthy controls (P < 0.001). MMP activity levels in the serum of RA patients were correlated with ESR (r = 0.72, P < 0.001). CONCLUSION: In the systemic circulation of RA patients, active MMPs form complexes with alpha 2M and can be detected using LMW fluorogenic substrates. MMP activity measurements in serum allow discrimination between RA patients and healthy controls and provide a new tool for the assessment of the disease process in RA.

Adult↗