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Biomedical subjects

D Groothuis

Publications and source records attributed to D Groothuis.

13 recordsLinked to original sources
PubMed1993

Serovar determination and molecular taxonomic correlation in Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum: a cooperative study of the International Working Group on Mycobacterial Taxonomy.

A cooperative study was conducted by the International Working Group on Mycobacterial Taxonomy to correlate the agglutination serovar designations of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum strains with the species ascriptions of these organisms according to molecular criteria and cultural properties and to assess the reproducibility of serovar determinations for a set of 63 reference strains of these species. Among the molecular criteria, the level of agreement between results obtained with nucleic acid probes and T-catalase serology results was 94% for strains of M. avium and M. intracellulare. Nucleic acid probes were not available for M. scrofulaceum, but none of the 10 strains ascribed to this species on the basis of catalase serology data reacted with a nucleic acid probe for M. avium or M. intracellulare. Ascription to a species on the basis of mycolic acid high-performance liquid chromatography patterns was in agreement with catalase serology results in 86% of the cases examined. Most strains belonging to serovars 1 through 6 and 8 through 11 were identified by molecular criteria as M. avium, most strains belonging to serovars 7, 12 through 20, 23, and 25 were identified as M. intracellulare, and most strains belonging to serovars 41 through 43 were identified as M. scrofulaceum, in agreement with common current practice. Evidence for assigning serovar 27 to M. scrofulaceum was obtained. However, two strains of a given serovar may, on occasion, be placed in different species. The dominant species assignments for strains belonging to serovars 21, 24, 26, and 28 remain unresolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1992

Do cancers invade veins?

It is postulated that all malignant tumors spread in the same way. They invade through the basement membrane, spread through the interstitial compartment for variable distances, enter a lymphatic vessel through natural clefts, and reach the vascular compartment through lymphatic venous anastomoses or terminal lymphatics. The brain would seem to be an ideal site to test these ideas since it contains no lymphatic vessels. Injections of a well-characterized murine mammary tumor into the brains of 123 mice resulted in growth of the tumor in 82 mice (67%). Autopsy revealed only five cases in which there was distant tumor that had invaded beyond the brain.

Animals↗
PubMed1984

Analytical pyrolysis of Streptococcus salivarius as an aid to identification in bite-mark investigation.

The use of pyrolysis mass spectrometry (Py-MS) and statistical analysis of mass spectra is introduced as a method for "finger-printing" strains of Streptococcus salivarius. The objective is to provide correlative evidence regarding the identity of suspects in cases of assault or rape involving bite-marks. The results of the analysis of isolates from two individuals are presented, illustrating the differentiation of S. salivarius at strain level according to the origin of the isolate.

Bites and Stings↗
PubMed1984

Regional thymidine transport and incorporation in experimental brain and subcutaneous tumors.

The regional distribution and local incorporation of [14C]thymidine into a nonextractable tissue fraction, probably DNA, was measured in normal and neoplastic tissues. We studied brain tumors induced by avian sarcoma virus and ethylnitrosourea, and transplanted RG-2 intracerebral and subcutaneous gliomas. An incorporation quotient, Q, was calculated for different tumor regions and brain from the methanol nonextractable radioactivity in the tissue and the plasma concentration-time integral of thymidine. The incorporation quotient represents the rate of clearance of thymidine from blood and its incorporation into macromolecules (probably DNA). The values of Q were compared with a labeling index measured in the same tissue regions with conventional autoradiography. The following observations were made: (1) the mean plasma half-life of thymidine was 6.5 min; (2) the regional incorporation quotient in tumors varied from values comparable to normal brain to more than 100 times higher; (3) RG-2 tumors had significantly higher Qs than the other tumor models; (4) Q in subcutaneous tumors varied most widely (greater than 500-fold range); (5) the labeling index reflected the values of Q in some tumor regions but not in others; differences between the two were most frequently related to tumor cell density and the intensity of individual tumor cell labeling. A comparison of these data with previous studies of capillary permeability and blood flow in these tumor models indicates that the incorporation of [14C]thymidine into a nonextractable tissue fraction can be limited by transcapillary transport in brain tumors and by blood flow in systemic tumors, and that thymidine disposition in these tumors is not always indicative of the rate of DNA synthesis.

Animals↗
PubMed1984

The effect of graded hypertonic intracarotid infusions on drug delivery to experimental RG-2 gliomas.

The RG-2 brain tumor model was used to determine whether unidirectional transport of alpha-aminoisobutyric acid (AIB) into brain and tumor tissue was increased after an intracarotid infusion of one of six different hypertonic solutions of L-arabinose. Intracarotid infusion of hypertonic solutions that have been reported as subthreshold for normal brain were used to determine whether they would selectively increase blood-to-tissue transport in brain tumors. No increase in the transport rate constant (K) across RG-2 tumor capillaries resulted from the infusion of 0.8- to 1.4-osm solutions. Infusions of 1.6- and 1.8-osm solutions were also performed, and blood-to-tissue transport was measured under conditions that produce maximum blood-brain-barrier disruption; however, no increase in the transport rate across tumor capillaries was measured. In brain regions surrounding the tumor, there was a trend toward increasing K values associated with increasing osmolality of the infusate, but the magnitude of this increase was small. There was a progressive increase in the K of tumor-free brain regions. This increase correlated with increasing osmolality of the infusate (0.8 to 1.8 osm). We conclude that intracarotid infusion of hypertonic solutions of L-arabinose does not increase the rate of delivery of water-soluble drugs to experimental RG-2 brain tumors. In this situation, the use of hypertonic infusions may be counterproductive and result in a greater delivery to and exposure of surrounding and normal brain tissue to levels of chemotherapeutic drugs which are potentially neurotoxic.

Aminoisobutyric Acids↗
PubMed1983

Regional blood flow in ethylnitrosourea-induced brain tumors.

Regional blood flow was measured in experimental brain tumors using iodoantipyrine labeled with carbon 14 and quantitative autoradiography. A total of fifteen oligodendrogliomas, sixteen mixed gliomas, one astrocytoma, one ependymoma, and three malignant schwannomas were studied in 9 rats. The mean tumor blood flows for all glioma classifications were similar, averaging 45 +/- 3 (standard error of the mean) ml . hg-1 . min-1. Flow was fairly uniform within individual oligodendrogliomas and there was no apparent correlation between blood flow and tumor size or location. The mixed gliomas were larger than the oligodendrogliomas and had a wider range of blood flow. Small focal areas of necrosis were observed in 7 mixed gliomas, and low flows were usually measured in these regions; these flows were not always the lowest regional values measured within the mixed gliomas or total group of tumors, however. Small tumor regions with increased vascularity, frequently with endothelial cell proliferation, were observed in oligodendrogliomas and to a greater extent in mixed gliomas; these regions were correlated with small elevations in blood flow (10 to 15 ml . hg-1 . min-1) in comparison with surrounding tumor tissue. Brain adjacent to tumor usually had higher blood flows than that in tumor periphery. Hemispheric differences in blood flow related to the site of primary tumor growth were not observed.

Animals↗
PubMed1983

Regional blood-to-tissue transport in ethylnitrosourea-induced brain tumors.

Regional blood-to-tissue transport, expressed as a unidirectional transfer rate constant (K), was measured in experimental brain tumors using alpha-aminoisobutyric acid (AIB) labeled with carbon 14 and quantitative autoradiography. A total of sixteen oligodendrogliomas, four mixed gliomas, three astrocytomas, two diffuse gliomatosis, one anaplastic astrocytoma, one ependymoma and four malignant schwannomas were studied in 9 rats. The mean Ks for all glioma classifications were similar, averaging 2.6 +/- 0.4 (standard error of the mean) ml . kg-1 . min-1, and were only slightly higher than those for nontumorous parietal cortex (2.1 ml . kg-1 . min-1), corpus callosum (0.9 ml . kg-1 . min-1), and a comparable region of brain tissue in the contralateral hemisphere (1.3 ml . kg-1 . min-1). Values of K varied minimally in the intracerebral gliomas and were marginally correlated with tumor cell morphology in only two tumors. In some (but not all) of the larger gliomas, increased vascularity, with or without endothelial proliferation, was associated with a 3- to 15-fold increase in K. Regional K values in malignant schwannomas were highly variable (4 to 207 ml . kg-1 . min-1) and generally were not correlated with specific histological features of the tumor, except in some regions with increased vascularity. Estimates of the average fractional extraction of AIB by the intracranial gliomas and malignant schwannomas were 0.01 and 0.2, respectively; average fractional extractions for nontumorous brain were approximately 0.003.

Aminoisobutyric Acids↗
PubMed1983

Regional blood flow in avian sarcoma virus (ASV)-induced brain tumors.

Regional blood flow (F) was measured in avian sarcoma virus (ASV)-induced brain tumors in rats. Blood flow was variable in individual as well as different tumors; tumor F did not correlate with histologic classification, tumor size, central versus peripheral tumor regions, intraparenchymal location, cell density, or specific cytologic characteristics. Low values of F did correlate with tumor necrosis and hydrocephalus; high values of F correlated with tumorous invasion or association with choroid plexus. Mean tumor F was not significantly different from that of the same anatomic, tumor-free brain region of the contralateral hemisphere, but F in brain tissue adjacent to the tumor was depressed significantly. Depression of F was observed in tumor-free cortex and corpus callosum, especially in the hemisphere ipsilateral to the main tumor mass and in those animals with hydrocephalus.

Animals↗
PubMed1983

Regional blood-to-tissue transport in avian sarcoma virus (ASV)-induced brain tumors.

Regional blood-to-tissue transport of 14C-alpha-aminoisobutyric acid (AIB) was measured in avian sarcoma virus (ASV)-induced rat brain tumors and expressed as a unidirectional transfer rate constant (K). The magnitude of K was variable and did not correlate with histologic classification or specific features of the tumors, with the possible exception of sarcomas. Averaged mean K was highest for anaplastic astrocytomas and lowest for gemistocytic astrocytomas (GA); however, the range of measurement within the individual tumor classifications (except GA) was broad. K was not consistently related to tumor size or tumor location; choroid plexus and subependymal tumors were exceptions and had higher K values. The averaged mean K of tumor-free brain in the contralateral hemisphere (CBA) was comparable to that of control animals. The averaged mean K in brain adjacent to tumor was greater than in CBA and generally one-third to one-half of the value in tumor periphery, indicating that these tumors affect the permeability characteristics of adjacent brain capillaries. Estimates of the fractional extraction (E) of AIB by the tumors ranged between 0.009 and 0.2; E's in this range indicate that tumor capillaries are not freely permeable to this solute.

Animals↗