Biomedical subjects
Publications and source records attributed to D C Wright.
Canine cerebrospinal fluid rhinorrhea, which occurs frequently in purebred beagles, was demonstrated in two dogs on magnetic resonance images after cisternal introduction of gadolinium-DTPA dimeglumine.
Treatment of brain tumors by intra-arterial (IA) chemotherapy is occasionally complicated by sites of focal toxicity in the brain and retina. A possible cause of focal toxicity is non-uniform drug delivery due to intravascular drug streaming. To investigate this phenomenon in vivo, the authors examined the distribution of drug delivery after internal carotid artery (ICA) infusion in rhesus monkeys. Carbon-14 (14C)-labeled iodoantipyrine was delivered into the ICA of eight monkeys at slow infusion rates (1% to 2% of ICA flow) or at fast infusion rates (20% of ICA flow) combined with additional techniques to promote mixing with ICA blood. Two monkeys received intravenous (IV) 14C-antipyrine. Uniformity of delivery was assessed by comparing high-to-low ratios of isotope concentration in four brain regions evaluated by quantitative autoradiography. There was striking non-uniformity of drug delivery in the slow IA infusion group, with as much as 13-fold differences in drug concentration in anatomically contiguous areas. The values of high-to-low concentration ratios (mean +/- standard deviation) in individual autoradiographic planes were: 1) frontoparietal cortex: slow IA infusion 4.54 +/- 2.07, fast IA infusion 1.71 +/- 0.31, IV infusion 1.30 +/- 0.174; 2) frontoparietal white matter: slow IA infusion 2.94 +/- 1.45, fast IA infusion 1.59 +/- 0.41, IV infusion 1.34 +/- 0.21; 3) temporal cortex: slow IA infusion 5.43 +/- 3.57, fast IA infusion 1.69 +/- 0.24, IV infusion 1.67 +/- 0.25; 4) basal ganglia: slow IA infusion 3.6 +/- 2.9, fast IA infusion 1.18 +/- 0.10, IV infusion 1.09 +/- 0.04. Differences between concentration ratios after slow IA and fast IA infusion are significant (p less than 0.01); those between fast IA and IV infusion are not significant. Intra-arterial drug administration at infusion rates analogous to those currently used clinically results in drug streaming with markedly heterogeneous drug deposition in the perfused hemisphere. This may cause suboptimal drug levels in the tumor, and toxic levels at sites within the perfused hemisphere. This effect can be abrogated by techniques that eliminate drug streaming.
Thirty-seven percent (15/41) of patients with human T-cell lymphotropic virus type III (HTLV-III) disease (acquired immunodeficiency syndrome [AIDS] or AIDS-related complex) sequentially evaluated at Walter Reed Army Medical Center, Washington, DC, acquired this infection from a partner(s) of the opposite sex. Demographic features of these 15 patients (ten males and five females) differed substantially from those for patients reported to the Centers for Disease Control. Heterosexual contact with partners who developed AIDS or who were at risk for AIDS was confirmed in six patients. The remaining nine patients had multiple (greater than 50) heterosexual partners and/or sexual contact with prostitutes. The method of sexual activity did not appear to be related to disease acquisition; however, this study clearly demonstrated that receptive anal intercourse was not a requirement. The observations reported herein provide further epidemiologic evidence to support the occurrence of bidirectional heterosexual transmission (both male to female and female to male) of HTLV-III infection and disease.
Seven cases of acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) associated with human T-cell leukemia (lymphotropic) virus (HTLV)-III infection were documented in married males whose family members consented to medical evaluation. Five spouses also had evidence of HTLV-III infection documented by isolation of virus and by detection of serum antibody directed against viral structural proteins. Three of the five HTLV-positive spouses also had clinical evidence of ARC. The remaining four spouses were clinically healthy. Eleven children (between 14 months and 13 years of age) were also evaluated for evidence of disease and exposure to HTLV-III. Only one 14-month-old child was seropositive for antibody to HTLV-III. These data support the opinion that close household contact to patients with ARC or AIDS is not an efficient mechanism for virus transmission, while demonstrating that HTLV-III can be transmitted by repeated heterosexual contact.
A rapid, sensitive immunoenzymatic technique for the analysis of lipopolysaccharide (LPS) from gram-negative bacteria using monoclonal antibodies is described. After separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the LPS was either stained with silver or electrophoretically transferred to nitrocellulose. After reaction with anti-LPS monoclonal antibodies, the transferred antigens were visualized by reaction with alkaline-phosphatase-labelled anti-mouse antibodies and a substrate containing naphthol phosphoric acid and Fast Red.
Use of interstitial radiation holds promise in the treatment of primary malignant brain tumors, but optimal technical factors have yet to be determined. We have developed a method of precise CT directed stereotactic placement of radioactive sources in a predetermined target volume. We use low activity (1-2 millicurie/speed) sources of 125I loaded in silastic catheters, which are positioned in a parallel array in the target. Positioning of such multiple sources toward the periphery of the volume enhances achievable dose homogeneity. Seeds of various activities can be differentially loaded into each catheter and the catheters can be positioned at various radii from the central target so that the treated volume corresponds to the identified (often irregular) target volume. Although the implant is designed to be permanent, the sources can be removed easily in a second procedure.
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Mouse monoclonal antibodies that react with O-side chain specific, O-side chain cross-reactive, and core P. aeruginosa lipopolysaccharide determinants have been isolated. The monoclonals directed at O-side chain determinants are generally opsonophagocytic with human neutrophils and human complement. They also protect mice from intraperitoneal and intravenous challenge and protect in the burned rat model of infection.
The clinical presentation and the results of operative and radiation therapy in a series of 26 patients with cranial chordomas seen at the University of California, San Francisco, between 1940 and 1984 are reviewed. There were 14 men and 12 women, with a mean age of 39.6 years. Six patients had chondroid chordomas. The most common presenting symptoms were headache and diplopia, and the most common presenting sign was extraocular palsy. Fifty-three operations directed at removal of the tumor were performed. Twenty-three patients received various forms of radiation therapy postoperatively, including conventional external beam therapy, heavy charged particles, and interstitial implants. The average length of follow-up is 5.6 years. Eleven of 26 patients have died; the mean duration of survival in this group, excluding 1 perioperative death, was 4 years and 2 months. Although the average survival time of 6 years and 4 months was the same in patients with typical chordomas (excluding the perioperative death and 1 patient lost to follow-up) and in those with the chondroid variant, all of the latter are still alive, whereas more than half of the patients with typical chordoma have died.
A patient with fatal Yersinia enterocolitica sepsis was seen recently in our intensive care unit. The patient had received two units of packed red blood cells during a surgical procedure. Cultures of the donor blood yielded Y enterocolitica, and a whole-organism enzyme-linked immunosorbent assay of the donors' sera suggested a recent infection with Y enterocolitica in an asymptomatic donor. Though rare, Y enterocolitica, which can grow at the cold temperatures of refrigerated blood, should be considered as a possible source of sepsis following blood transfusion.
Data from earlier investigation of Au-Cu-Ag ternary alloys indicate that there may be a relationship between an alloy's corrosion behavior and its biological effects. Corrosion properties were determined using standard potentio dynamic techniques and the biological effect was assessed as cytotoxicity in vitro. Linear mathematical methods were used to analyze the data and model the systems. A direct correlation was found between corrosion properties and cytotoxic response.
This presentation describes a battery of quantitative in vitro tarnish tests for cast dental alloys. Eleven commercial alloys representing the available nobility range in precious fixed prosthodontic alloys were used to establish typical responses to the tests. Below approximately 55 at.% noble metal content, microstructure plays a dominant role in determining tarnish resistance. Thus, through proper alloy design and heat treatment, low nobility alloys can be designed with acceptably low tarnish susceptibility. The availability of these quantitative tests will allow determination of relative tarnish resistance and aid in establishing criteria for dental alloys. Furthermore, the data and test criteria developed in this study will provide a method for comparing alloys and designing improved lower cost alloys.
Effects of decreased alloy nobility are measured with respect to copper and silver corrosion activity. A potentiodynamic technique is developed for this analysis. It is shown that cooper and silver have characteristic potentials for which individual current densities are maximal. Identification of characteristic potentials allows the definite analysis of 11 commercial crown and bridge alloys for copper and silver corrosion. It is shown that microstructure, as well as alloy chemistry, plays a major role in determining corrosion resistance.
Drug delivery to tumours and the accessibility of tumour cells to drugs remains a problem of foremost importance and is affected by many factors. We will discuss models we have developed for drug delivery from tumour capillaries to tumour cells, and drug delivery from well perfused, well oxygenated tumour regions to less well perfused hypoxic regions in terms of computer simulation of drug delivery for the anticancer agent BCNU and the hypoxic cell radiosensitizer misonidazole.
The surgical therapy and results in 17 cases of basilar aneurysms are reported, extending a series of 15 reported previously. Three surgical approaches were used: subtemporal, pterional, and suboccipital. The subtemporal route was satisfactory for most lesions, although the pterional approach has advantages for upper basilar aneurysms projecting either more than 1 cm above the dorsum sellae or directly anteriorly. A low lateral-suboccipital approach is described and recommended for aneurysms of the proximal basilar trunk and vertebrobasilar junction. The recent literature regarding surgical results, classification, pathogenesis, and technical developments for management of these lesions is reviewed. Most of the morbidity resulting from surgery in the midbrain and pontine region is due to direct or indirect injury to perforating vessels. Superiorly directed bifurcation aneurysms carry the highest risk because of their association with perforating vessels. General precepts regarding size, location, patient condition, and timing of operation with respect to aneurysms of the anterior circulation hold true for aneurysms of the posterior circulation.
Methyl alpha- and beta-D-xylopyranoside-5-18O (5 and 6) were prepared by way of oxygen exchange between 18O-water and the periodate-oxidation product (1) obtained from 1,2-O-isopropylidene-alpha-D-glucofuranose. The isotopic enrichment of 5 and 6 was determined by hydrolysis of each to D-xylose-5-18O (3), conversion of the sugar into 1,2,3,4-tetrakis-O-(tert-butyldimethylsilyl)-beta-D-xylopyranose-5-18O (7), and determination of the 18O content of the latter by use of a quadrupole, mass spectrometer.
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