Biomedical subjects
D Buck
Publications and source records attributed to D Buck.
Skin fibroblast microtubular network in Alzheimer disease.
A preliminary observation from another laboratory recently suggested that a systemic microtubular defect may exist in Alzheimer disease. To investigate this hypothesis, we obtained skin biopsies from 4 patients with Alzheimer disease and 2 age-matched controls. Fibroblast cultures were established and the tubulin networks examined using immunoadsorbent purified antitubulin antibody and the indirect immunoperoxidase technique as well as electron microscopy. The cells were also examined after treatment with vinblastine and at senescence. The microtubular network appeared as delicate fibers radiating from the perinuclear region toward the cytoplasmic margins. No differences were recognized between the controls and the fibroblast cultures from patients with Alzheimer disease. Microtubules were not visualized following incubation with vinblastine, but positively staining intracytoplasmic paracrystalline inclusions were noted. No abnormalities of microtubules were recognized in the electron microscopic examinations. These findings suggest that the neurofibrillary neuronal degeneration of Alzheimer disease is not a manifestation of a systemic disorder of the microtubular network.
Effects of tourniquet ischemia and postischemic edema on muscle metabolism.
In vivo interstitial muscle pressures measured by wick catheter, tissue gas tensions measured by mass spectrometer, and glucose and high-energy phosphate metabolism measured fluorometrically were studied in the anterior tibial (AT) and vastus lateralis (VL) muscles of primate limbs during and following tourniquet ischemia (2.5 hours; 400 mm Hg) to elucidate postischemic edema and its metabolic consequences. During ischemia, interstitial pressure in the VL rose, while in the AT it decreased, but 24 hours later pressures in both experimental muscles were significantly greater than those in the controls. In both experimental muscles PO2 decreased significantly within 15 minutes of ischemia. PCO2 increased significantly in the AT at 30 minutes and at 75 minutes in the VL muscle. Twenty-four hours later only PO2 in the experimental AT was significantly different than its matched control. During ischemia glucose and phosphocreatine (CrP) decreased significantly, and G-6-P and lactate increased significantly in both muscles, but at 24 hours glucose levels were 25% lower and G-6-P 16.2% higher in the experimental AT and CrP 34% lower in the experimental VL. This study shows that there are significant acute and delayed alterations in primate muscle metabolism following tourniquet ischemia and suggests that these changes may be related to the anatomic location of the muscle studied and the type of trauma it has sustained.
Intravascular coagulation and fibrinolysis within primate extremities during tourniquet ischemia.
A common although infrequently recognized complication associated with the use of a pneumatic tourniquet is profuse bleeding from the wound after deflation of the tourniquet. The purpose of this study was to determine whether intravascular coagulation and fibrinolysis could be induced in subhuman primates by tourniquet ischemia, and whether this phenomenon could be altered by pretreatment of the animal with heparin. It was shown that, after 2(1/2) hours of tourniquet ischemia, (400 mmHg) to one lower limb, fibrinogen levels were significantly lower (p < .005), antithrombin III levels were significantly lower (p < .05), plasminogen levels were significantly lower (p < .05), fibrin split products significantly higher (p < .025) and fibrinopeptide A levels were significantly higher (p < .02) than values measured simultaneously in the control limbs. After pre-treatment with sodium heparin, 30 units/kg, there was no change in antithrombin III levels or fibrinogen levels, but fibrin split products in the experimental limbs were significantly elevated (p < .05) when compared to control limbs. In both groups the abnormal levels returned to control levels 5-30 minutes after tourniquet deflation. We conclude that intravascular coagulation and fibrinolysis develop within ischemic subhuman primate limbs during tourniquet ischemia. Pretreatment with heparin prevents the consumption of fibrinogen and antithrombin III but does not prevent the increase in fibrin split products which was observed. It is possible that intravascular coagulation and fibrinolysis contribute to post tourniquet bleeding.
Congenital mesoblastic nephroma.
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The uptake of H3 proline in the guinea pig gingiva and palate.
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The DNA sequence and comparative analysis of human chromosome 20.
The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.
Rapid production of recombinant allergens in Nicotiana benthamiana and their impact on diagnosis and therapy.
BACKGROUND: Type I allergies are immunological disorders that afflict a quarter of the world's population. Recombinant allergens have improved the diagnosis of allergic diseases and allow the formulation of new therapeutic approaches. Over 50% of all allergens are of plant origin. OBJECTIVE: We have applied a novel method of overexpressing plant allergens in the tobacco-related species Nicotiana benthamiana. METHOD: This method is based on the use of a chimeric tobacco mosaic virus that harbors a foreign gene sequence and directs its transcription after the infection of the host plant. RESULTS: We have expressed the model allergen Bet v 1, the major birch pollen allergen, and two Hevea brasiliensis latex allergens, the spina-bifida-associated allergens Hev b 1 and Hev b 3, in N. benthamiana using such a viral vector. Bet v 1, Hev b 1 and Hev b 3 produced by this method were recognized by patients' IgE suggesting that the plant-produced allergens were properly folded. Nonpurified Bet v 1 expressed in N. benthamiana leaves had the same immunogenicity as purified Bet v 1 expressed in Escherichia coli or natural Bet v 1 when tested in a murine model of type I allergy. CONCLUSION: We conclude that this plant expression system offers a viable alternative to fermentation-based production of allergens in bacteria or yeasts.
Jamestown Canyon virus: seroprevalence in Connecticut.
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Eighteen-month radiographic and histologic evaluation of sinus grafting with anorganic bovine bone in the chimpanzee.
Maxillary sinus grafting procedures are currently the treatment of choice when the alveolar crest of the posterior maxilla is in close approximation to the maxillary sinus. The short-term histologic and radiographic healing following sinus grafting with natural bone mineral (Bio-Oss) in the chimpanzee has been evaluated. We have previously shown by histomorphometric and radiographic analysis that the percentage of vital bone area, the vertical height, and the density of new bone in the maxillary sinus was significantly greater with anorganic bovine bone compared to bovine Type I collagen matrix. The purpose of this in vivo study was to determine the bone mineral density (BMD) of the sinus grafts, the vertical height stability, the vital bone area, and the extent of anorganic bovine bone replacement 18 months postoperatively in 4 maxillary sinuses from 4 different animals. Radiographic analysis of computed tomographic scans taken at 1.5 years revealed an average BMD of 658 mg/mL, which was not significantly different from the values found at 6.5 months. The radiographic vertical height was maintained between the 6.5- and 18-month time points. On average, the grafts were found to have a height of 14 mm. Lateral wall biopsy specimens at 7.5 months were compared to those at 18 months. With the anorganic bovine bone treatment, the percentage of vital bone area increased from 62 +/- 3% to 70 +/- 7% and the percentage of natural bone mineral area decreased from 19 +/- 14% to 6 +/- 3%. The bovine Type I collagen matrix vital bone percentage at 7.5 months was 34 +/- 21%. These results demonstrate that sinus grafting with anorganic bovine bone maintains radiographic evidence of density and height stability of 1.5 years. In addition, histologic evidence supports the hypothesis that anorganic bovine bone is replaced by vital bone.