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Biomedical subjects

C D Johnson

Publications and source records attributed to C D Johnson.

At least 289 records · Page 16Linked to original sources
PubMed1987

Percutaneous balloon dilatation of ureteral strictures.

Percutaneous balloon dilatation of ureteral strictures has not gained widespread acceptance, despite proven success with the techniques for dilating stenotic blood vessels. Thirty-one ureteral strictures (in 30 patients) that were dilated during a 42-month period were reviewed to assess the results and to determine which patients are most likely to benefit from the procedure. Eighteen (58%) of 31 strictures were successfully dilated and remained patent for at least 6 months. Thirteen (42%) of 31 strictures resulted in failed patency either immediately (two patients) or within 3 months (seven patients), 6 months (three patients), or 21 months (one patient). Fourteen (64%) of 22 strictures less than 7 months of age were successfully dilated. All dilations for strictures more than 7 months of age failed. Four strictures were of unknown age. Nine (69%) of 13 strictures located in the proximal or midureter remained patent, and three (60%) of five dilations at a ureteroileal anastomosis were successful. Neither of two strictures at a ureterocolic anastomosis was treated successfully. We conclude that percutaneous balloon dilatation is an effective treatment of ureteral strictures in some patients, especially when the strictures are less than 7 months of age.

Adult↗
PubMed1987

Renal adenocarcinoma: CT staging of 100 tumors.

The preoperative CT scans of 100 pathologically proven renal adenocarcinomas were retrospectively reviewed to assess the accuracy of CT for staging the tumor. Regardless of tumor stage, perinephric extension was assessed with a sensitivity of 46% and a specificity of 98%. The sensitivity of CT in detecting venous invasion (either venous enlargement or thrombus) was 78%, with a specificity of 96%. For detection of metastatic adenopathy, CT had a sensitivity of 83% and specificity of 88%. Adjacent organ invasion was correctly identified in 60% of patients, with a specificity of 100%. Overall, CT correctly staged 91% of patients. If errors associated with perinephric invasion were excluded, CT staging accuracy improved to 96%. CT is useful in staging renal adenocarcinoma. If the renal vein is not well seen, angiography or sonography may be necessary to determine the presence of venous tumor extension.

Adult↗
PubMed1987

Diagnosis of acute colonic diverticulitis: comparison of barium enema and CT.

The contrast enema and CT studies in 102 patients with a clinical diagnosis (41%) or surgically confirmed (59%) diagnosis of colonic diverticulitis were reviewed retrospectively to determine the sensitivity of the two techniques. Combined results from all patients showed that the contrast enema was correct in 77% of patients. The contrast enema was falsely negative in 15% and was indeterminate in 7%. The CT examination was diagnostic in 41%, consistent with the diagnosis of diverticulitis in 38%, and falsely negative in 21% of patients. Both CT and contrast enemas were more accurate in patients with severe disease requiring surgery. No complications occurred from 109 enemas performed. Patient management was altered in only one patient as a result of the additional information provided by CT. The contrast enema should remain the initial and routine examination for the evaluation of patients with suspected diverticulitis. CT should be reserved for patients who are unable to have an adequate contrast enema, those with suspected distant or diffuse abdominal abscess, those who are unresponsive to medical therapy, and those who are candidates for percutaneous drainage.

Acute Disease↗
PubMed1987

Two-second MR images: comparison with spin-echo images in 29 patients.

MR images can be obtained with a 2-sec scan time when an extremely short repetition rate (22 msec), limited flip angle (30 degrees), and gradient refocused echoes are used. Comparison of 415 such images obtained in 29 patients with routine T1-weighted (TR 500, TE 25) and T2-weighted (TR 2000, TE 80) images showed that images free of respiratory artifacts could be obtained in all patients. Although abdominal organs were well seen with 2-sec scan time, overall evaluation of these organs was better on routine T1-weighted images. Vascular structures, however, were seen as well or better on the 2-sec images in 60% of cases. The images were extremely sensitive to field nonhomogeneity, and metallic artifact was exaggerated in five patients with surgical clips. Two-sec MR images provide a rapid method of localizing abdominal organs for further evaluation. The sensitivity to blood flow may assist in the assessment of vascular patency.

Adrenal Glands↗
PubMed1987

The toxic effects of ethylcholine mustard aziridinium ion on cholinergic cells in the chicken retina.

The chicken retina has been used to examine the toxicity of a highly reactive chemical analog of choline, ethylcholine mustard aziridinium ion (ECMA). Following a single intravitreal injection, retinas were analyzed biochemically for CAT and AChE activities, and GABA, glycine, and dopamine levels. Retinas were also examined using histofluorescence for dopamine histochemistry, for AChE, and immunohistochemistry with antibodies to CAT, tyrosine hydroxylase, GABA, 5-HT, Leu-enkephalin, and somatostatin. A dose of 50 nmol ECMA caused a prolonged 70% depletion of CAT activity and a 40% depletion of AChE activity. The other biochemical parameters were unchanged. This result corresponds to the morphological finding that 2 populations of cholinergic cells were destroyed and that the AChE activity associated with their terminal arbors was lost. A third population of cholinergic cells, located towards the middle of the inner nuclear layer, was resistant to the toxic effects of ECMA. The other cell types, except for somatostatin-immunoreactive cells and photoreceptors, which showed transient effects, were unaffected. ECMA therefore appears to be a highly specific toxin for cholinergic cells in the retina.

Acetylcholine↗
PubMed1987

GABA-immunoreactivity in inhibitory motor neurons of the nematode Ascaris.

We have used GABA-specific antisera to detect GABA-immunoreactivity in the motor neurons of the ventral nerve cord of Ascaris. We find that a subset of the individually identifiable commissures of motor neurons is specifically stained. On the basis of the location and morphology of stained commissures and of the location of stained cell bodies in the ventral nerve cord, we conclude that the labeled neurons comprise all members of the VI (inhibiting ventral muscle; 13 cells) and DI (inhibiting dorsal muscle; 6 cells) classes of inhibitory motor neurons (Stretton et al., 1978; Walrond et al., 1985). This result supports previous suggestions (e.g., del Castillo et al., 1964b) that GABA is the neurotransmitter released by the inhibitory motor neurons of nematodes. In the anterior part of the animal, the inhibitory motor neuron commissures have small branches in the sublateral nerve cords that have not been previously described: VI commissures have dorsal sublateral branches, while DI cells have ventral branches. Posterior VI neurons have branches in the lateral nerve cords.

Animals↗
PubMed1987

Two alternative methods for tying the surgeon's knot with one hand.

After a recent description of a one handed method of tying a surgeon's knot, two further methods are described. It is suggested that three double throws produce a safe knot for monofilament sutures. Using a method described herein, such a knot can be tied elegantly and quickly.

Suture Techniques↗
PubMed1986

Putative cholinergic interneurons in the optic tectum of goldfish.

We have demonstrated that a significant fraction of cells in layer 1 of goldfish optic tectum are immunoreactive for choline acetyltransferase. These cells constitute 4-7% of type XIV cells, which are thought to be intrinsic neurons and represent 95% of all tectal cells. The number of immunoreactive type XIV cells is unchanged following short-term enucleation. The possible integrative role of these putative cholinergic neurons is discussed in relation to sensory functions of the optic tectum.

Animals↗
PubMed1986

Neural pathways for the release of gastrin, cholecystokinin, and pancreatic polypeptide after a meal in dogs. Role of gastric and splanchnic nerves.

We have measured gastrin, cholecystokinin (CCK), and pancreatic polypeptide (PP) release after a meal in normal dogs under basal conditions and during atropine infusion, and after various neural sections. Denervation of the gastric antrum (antral vagotomy) abolished the early part of the gastrin response to food. Truncal vagotomy, celiac ganglionectomy, and atropine reduced the early release of CCK, which occurred before the start of gastric emptying, suggesting that a neural, cholinergic mechanism may release CCK immediately after a meal. PP release was abolished by truncal vagotomy, and also by antral vagotomy. As no direct pathways are known between the antrum and the pancreas, this suggests either that antral afferents are essential for this response or that vagally mediated hormone release from the antrum mediates PP release.

Animals↗
PubMed1986

Intraoperative antegrade lavage and anastomotic healing in acute colonic obstruction.

The management of acute distal colonic obstruction remains controversial. The advent of intraoperative colonic irrigation has allowed primary anastomosis to be performed in obstructed bowel. Fifteen patients, with acute distal obstruction due to carcinoma, diverticulitis or sigmoid volvulus were managed by primary resection and anastomosis. There were two leaks (14 percent) and the duration of operation was prolonged. In an experimental study of anastomotic healing after acute obstruction, intraoperative irrigation improved early anastomotic colonic collagen content (P less than 0.02) and perianastomotic proximal and distal collagen content (P less than 0.002, P less than 0.05). Intraoperative lavage is a useful technique to permit safer primary resection and anastomosis in obstructed colon.

Acute Disease↗
PubMed1986

Surgical complications of the Thomas pancreatic fistula.

This report describes the surgical complications of the Thomas pancreatic fistula in 23 dogs used for experiments for up to 1 year. Twenty animals survived the operation of cannula placement. The two complications noted were subcutaneous retraction of the cannula (nine of 40 cannulas) between 2 and 6 weeks, which was easily corrected, and displacement of the cannula from the gut lumen, which occurred eight times. Complete loss of the duodenal cannula was rapidly fatal. Partial displacement was corrected four times, with one death, using a specially developed technique. One lost gastric cannula was also replaced successfully. Corrective surgery for surgical complications of the Thomas fistula is feasible and has a high success rate. The preparation has a good long-term survival and so is suitable when repeated experiments in the same animals are required over a period of several months.

Animals↗
PubMed1986

Monoclonal antibodies and polyvalent antiserum to chicken choline acetyltransferase.

Monoclonal antibodies (mAbs) to chick choline acetyltransferase (ChAT) were obtained from mouse-hybridoma cultures after immunization with partially purified enzyme isolated from optic lobes. Antibodies that bound active enzyme were detected in 11 hybridoma cultures. The mAbs showed cross-reactivity to ChAT from quail and beef but not to ChAT from several other species. An affinity column prepared with one of the mAbs was used to purify ChAT to apparent homogeneity. Polyclonal antiserum to mAb affinity-purified ChAT was produced in a rabbit. This antiserum inhibited chick ChAT activity and quantitatively precipitated ChAT activity from solution. On immunoblots, the antiserum stained ChAT and two other proteins. After preadsorption of the antiserum with effluent from the mAb affinity column, the antiserum became monospecific for ChAT. This antiserum was useful for immunocytochemical localization of ChAT, it selectively stained neuronal cell bodies in chick spinal cord and rat brain at locations known to contain cholinergic neurons.

Animals↗
PubMed1986

Atrial synchronous ventricular inhibited (VDD) pacemaker-mediated arrhythmia due to atrial undersensing and atrial lead oversensing of far-field ventricular afterpotentials or paced beats: crosstalk.

A patient is described with an epicardial atrial or P wave synchronous ventricular inhibited VDD pacemaker which had atrial sensing malfunction manifesting as failure of atrial sensing, and atrial sensing of far-field ventricular polarization voltage afterpotentials or ventricular electrograms which mediated pacemaker allorhythms and tachycardias associated with dislocation of the atrial electrode near the right ventricle.

Adult↗
PubMed1986

An unusual volvulus--the ileosigmoid knot.

A case is presented of an ileosigmoid knot in a 70 year old man. A strangulated loop of ileum was wrapped around the neck of a sigmoid volvulus. Following small bowel resection and sigmoid colectomy with colostomy, the patient made an uneventful recovery.

Aged↗