Search PubMed⌕ Search

Biomedical subjects

D E Johnson

Publications and source records attributed to D E Johnson.

At least 325 records · Page 18Linked to original sources
PubMed1991

Clear-cell carcinoma in the trachea of a rat.

Necropsy examination of a control Sprague-Dawley male rat from a carcinogenicity study disclosed the presence of a neoplastic mass in the trachea. Microscopic examination disclosed that the tumor consisted of closely packed cells arranged in lobules and cords separated by thin connective tissue stroma. The cells had distinct cell borders and abundant pale cytoplasm. Electron microscopic examination further disclosed that the cytoplasm contained numerous argyrophilic neurosecretory granules measuring 298 nm in diameter. These granules were positive for Grimelius silver stain. The histopathologic and electron microscopic features of this tumor are consistent with a diagnosis of clear-cell carcinoma.

Adenocarcinoma↗
PubMed1991

Mouse models of short- and long-term foreign body in the urinary bladder: analogies to the bladder segment of urinary catheters.

Catheter-associated bacteriuria is the most common infection occurring in hospitals, where urethral catheters are generally in place for a few days, and in nursing homes, where catheters may be in place for months or years. We developed murine models with intrabladder urinary catheters for studying complications of bacteriuria in short- and long-term catheterization. In the short-term model, a catheter segment was inserted transurethrally and lay free within the bladder lumen. Half of the animals expelled segments during a 2-to-7-day period, durations similar to catheterizations in hospitalized patients. For studies of long-term catheter use, the catheter segment was secured within the bladder by a single suture for up to 12 months. Antibiotics administered for 7 days after catheter placement and housing mice in cages with wire screen floors reduced spontaneous bacteriuria to an acceptably low incidence rate of only 7%. Proteus mirabilis bacteriuria of high concentration provoked the same complications that are common in patients with long-term catheters: acute pyelonephritis, chronic renal inflammation, and struvite stone formation. These models allow inoculation of the bacteria of interest and are suitable for studies of short- and long-term foreign body-associated bacteriuria and its complications.

Animals↗
PubMed1991

Fatal acetaminophen poisoning with evidence of subendocardial necrosis of the heart.

The authors describe a case of fatal acetaminophen overdose which occurred in a 16-year-old female. Her serum acetaminophen concentration 11.5 h postingestion was 154 mg/L. Antidotal therapy was unsuccessful, and after 9 days she died. Autopsy findings included centrilobular zonal liver necrosis, acute proximal renal tubular necrosis, and diffuse alveolar pulmonary damage. Her heart was transplanted into a young woman with congenital heart disease. The recipient expired 14 days after the transplant as a result of sepsis complicating bowel ischemia. The transplanted heart showed extensive subendocardial myocyte necrosis related to acetaminophen toxicity and not rejection.

Acetaminophen↗
PubMed1991

Characterization of binding of the ATP-sensitive potassium channel ligand, [3H]glyburide, to neuronal and muscle preparations.

Binding of the hypoglycemic sulfonylurea, [3H]glyburide, to crude membrane fractions from brain, heart and smooth (intestinal) muscle was saturable, linear with protein concentration and reversible. Saturation analysis revealed high affinity sites (KH values, 7 x 10(-11) M, 5 x 10(-11) M and 6 x 10(-11) M), with Bmax-H values 209, 36 and 23 fmol/mg protein in the brain, heart and smooth muscle, respectively. High affinity [3H]glyburide binding was pharmacologically specific, insensitive to a variety of receptor-active ligands, but sensitive to a series of sulfonylureas, and good, essentially 1:1, correlations were obtained between binding affinities and literature-derived pharmacologic activities. The K+ channel activators, cromakalim, nicorandil, pinacidil and minoxidil were not effective as inhibitors of [3H]glyburide binding. However, diazoxide was a modestly effective inhibitor. Putative low affinity sites (KL values, 3 x 10(-7) M, 1 x 10(-7) M and 2 x 10(-9) M) with Bmax-L values 4956, 336 and 53 fmol/mg protein in brain, heart and smooth muscle, respectively, were identified. Their significance remains to be established. Except for ATP gamma S, the ability of nucleotide triphosphates to inhibit high affinity [3H] glyburide binding was dependent on the presence of Mg++. ADP, in the presence of Mg++, inhibited binding with an IC50 value of 6.3 x 10(-4) M. Nucleotide monophosphates did not inhibit [3H] glyburide binding in the presence or absence of Mg++, whereas in the presence of Mg++, nucleotide triphosphates were equally potent inhibitors of binding. The rank order potency for nucleotide diphosphate inhibition of binding, in the presence of Mg++, is ADP greater than GDP greater than IDP = UDP. In the absence of Mg++, [3H]glyburide binding shows a biphasic response to ADP, and the inhibition of binding by ADP was prevented by ATP. It is suggested that this biphasic response is the result of a second nucleotide binding site.

Adenosine Triphosphate↗
PubMed1991

Congenital absence of the pectoralis muscles in two collegiate wrestling champions.

Deficiency of the pectoralis major is a relatively common muscle anomaly. There is little documentation, however, of what, if any, functional deficit the anomaly imparts. Therefore, two highly successful amateur wrestlers with unilateral congenital absence of the pectoralis minor and sternocostal head of the pectoralis major are reported. Cybex testing revealed no appreciable decrease in shoulder internal rotation strength but did show a 20%-30% decrease in shoulder horizontal adduction strength. Other patients similarly affected can be advised that their shoulder strength will be slightly decreased, but significant functional limitations are unlikely.

Adult↗
PubMed1991

Yolk sac tumor of the liver.

A primary yolk sac tumor of the liver in a 16-mo female is presented. The fine needle aspiration biopsy (FNAB) cytology of this lesion is illustrated and discussed. This case supports continued exploration of the use of FNAB in childhood abdominal masses.

Biopsy, Needle↗
PubMed1990

Mechanism of insect resistance to the microbial insecticide Bacillus thuringiensis.

Receptor binding studies show that resistance of a laboratory-selected Plodia interpunctella strain to a Bacillus thuringiensis insecticidal crystal protein (ICP) is correlated with a 50-fold reduction in affinity of the membrane receptor for this protein. The strain is sensitive to a second type of ICP that apparently recognizes a different receptor. Understanding the mechanism of resistance will provide strategies to prevent or delay resistance and hence prolong the usefulness of B. thuringiensis ICPs as environmentally safe insecticides.

Animals↗