Search PubMed⌕ Search

Biomedical subjects

C D Johnson

Publications and source records attributed to C D Johnson.

At least 181 records · Page 10Linked to original sources
PubMed1994

A soldering index made with 4-META adhesive resin.

Soldering indexes are most often made of fast-setting impression plaster or autopolymerizing resin. Lack of adhesive bonding between these materials and the casting requires the use of a bulky index to support the fixed partial denture components. The advent of adhesive resins improves the quality of the index and simplifies the procedure. A procedure for making a soldering index with 4-META adhesive resin is described that involves direct bonding of the resin to the metal castings. This procedure is accurate, simple, and time-saving. It can be used inside or outside the mouth, in prosthodontic or implant dentistry.

Acrylic Resins↗
PubMed1994

The misdiagnosis of temporomandibular disorders in lateral pharyngeal space infections--two case reports.

Two cases of lateral pharyngeal space infections which were initially misdiagnosed as temporomandibular disorders (TMD) are presented and discussed. Such symptomatology as chronic facial pain, trismus and decreased inter-incisal opening provide many viable different diagnoses. It is important for the clinician to evaluate these different diagnoses in a logical manner. Conservative therapy is advised in the initial treatment of many TMDs, therefore other diagnoses with a greater potential for morbidity should be ruled in or out before the diagnosis of TMD is considered. The symptomatology of lateral space infections and the relevance of this entity to clinical dentistry are discussed.

Adult↗
PubMed1994

Non-adrenergic non-cholinergic inhibitory innervation shown by electrical field stimulation of isolated strips of human gall bladder muscle.

Non-adrenergic non-cholinergic (NANC) inhibitory nerves have been described in all regions of the gastrointestinal tract, but have not been shown previously in the human gall bladder. Electrical field stimulation was used in the presence of various agonists and antagonists to show NANC inhibitory innervation in strips of human gall bladder muscle. Gall bladder strips were set up isometrically in an organ bath containing oxygenated Krebs's solution. Electrical field stimulation was applied at 10 Hz, pulse width 0.3 ms and supramaximal voltage at intervals of 3 to 5 minutes. Of 60 strips that contracted in response to electrical field stimulation, 30 showed relaxation on electrical field stimulation in the presence of either carbachol (5-10 microM) or else atropine (0.5-2 microM) plus cholecystokinin octapeptide (0.01-0.1 microM) or caerulein (0.1 nM) or histamine (5-10 microM). In 22 strips this relaxation was not abolished by guanethidine (2-5 microM) showing the NANC nature of this response. The NANC relaxation was abolished by L-nitroarginine (100 microM) and this effect was partly reversible by L arginine (200 microM). All responses to electrical field stimulation were abolished by tetrodotoxin (0.2-2 microM). These results show for the first time a NANC inhibitory innervation in human gall bladder muscle. The probable neurotransmitter is nitric oxide.

Atropine↗
PubMed1994

CT findings in hepatocellular carcinoma: correlation of tumor characteristics with causative factors, tumor size, and histologic tumor grade.

PURPOSE: To determine computed tomographic (CT) findings of hepatocellular carcinoma (HCC) in a predominantly non-Asian population and to assess any morphologic differences with respect to causative factors, tumor size, and histologic grade. MATERIALS AND METHODS: Clinical history, pathology reports, histologic specimens, and CT findings in 100 patients with HCC were reviewed. All patients underwent contrast material-enhanced incremental dynamic CT. Findings were agreed on by consensus. RESULTS: The mosaic pattern was seen in 46% of cases, venous invasion in 33%, and tumor encapsulation in 31%; frequencies were similar to those reported with Asian patients. A mosaic pattern was more common in patients with larger tumors (P = .036). Venous invasion was more common in patients with alcohol-induced cirrhosis (P = .003) and in those with higher grade tumors (P = .043). Tumor encapsulation was more common in patients with lower grade tumors (P = .012). CONCLUSION: Reported morphologic differences between non-Asian and Asian patients with HCC may be due to differences in underlying liver disease, tumor size, and histologic grade.

Carcinoma, Hepatocellular↗
PubMed1994

Hepatic metastases and cavernous hemangiomas: distinction with standard- and triple-dose gadoteridol-enhanced MR imaging.

PURPOSE: To determine if hepatic metastases can be distinguished from cavernous hemangiomas by pattern analysis of magnetic resonance (MR) images obtained prior to and following administration of gadoteridol at standard (0.1 mmol/kg) and triple (0.3 mmol/kg) doses. MATERIALS AND METHODS: Ninety-five patients with proved hepatic metastases (n = 71) or cavernous hemangiomas (n = 24) underwent MR imaging at 16 different institutions. T2-weighted spin-echo and T1-weighted images were obtained before and after gadoteridol administration. Two independent blinded reviewers rated individual features of benignancy versus malignancy on a five-point confidence scale. RESULTS: The most useful diagnostic features, with 100% specificity, were nodular enhancement for hemangiomas and rim enhancement for metastases. Confident (definitely benign or definitely malignant) diagnoses were rendered in 80 of 95 cases (84%), with an accuracy of a confident diagnosis of 96%. CONCLUSION: The pattern of enhancement on T1-weighted images is highly accurate for distinction between hemangiomas and metastases in images obtained with both doses.

Contrast Media↗
PubMed1994

Pancreatic lesions in von Hippel-Lindau disease: prevalence, clinical significance, and CT findings.

OBJECTIVE: The purposes of this study were to determine the nature, prevalence, and CT findings of pancreatic lesions in patients with von Hippel-Lindau disease and to determine whether identification of pancreatic cysts and neoplasms is important in establishing the diagnosis of von Hippel-Lindau disease. SUBJECTS AND METHODS: The medical records and radiologic images of 52 patients with von Hippel-Lindau disease who were evaluated at our institution between 1976 and 1992, and who at some stage underwent abdominal CT, sonography, or MR imaging, were reviewed. The nature, prevalence, and CT findings of the pancreatic lesions were determined, and the role of the pancreatic abnormalities in establishing the diagnosis of von Hippel-Lindau disease was studied. RESULTS: Twenty-nine (56%) of the 52 patients had pancreatic lesions. Nineteen patients had pancreatic cysts and no other pancreatic lesion. Four patients had islet cell tumors only, one had a microcystic adenoma only, and three had indeterminate pancreatic masses. One patient had cysts and an islet cell tumor, and another patient had cysts, an islet cell tumor, and a microcystic adenoma. In six patients (12%), pancreatic lesions were the only abdominal manifestation of von Hippel-Lindau disease. In three patients screened because of a family history of von Hippel-Lindau disease, no CNS abnormalities were present, and the only abdominal lesions were in the pancreas (cysts in two cases, islet cell carcinoma in the other). Thus, the pancreatic lesion was an important factor in establishing a diagnosis of von Hippel-Lindau disease in these patients. CONCLUSION: Pancreatic lesions may be the only abdominal manifestation of von Hippel-Lindau disease. CT findings include cysts, islet cell tumors, and microcystic adenomas. Pancreatic lesions, including cysts, may precede any other manifestation of von Hippel-Lindau disease by several years, and recognition permits earlier diagnosis in patients being screened for von Hippel-Lindau disease.

Adenoma↗
PubMed1994

Prospective randomised trial of two devices for suprapubic catheterisation in general surgical patients.

Compared with urethral catheterisation, suprapubic catheterisation is associated with a reduced incidence of urinary infection and urethral stricture and it facilitates a controlled trial of micturition. A prospective comparison of two types of suprapubic catheter was performed in 70 patients, using a specially designed catheter mounted on a trocar for insertion (Suprapubic Ingram Trocar), and a disposable trocar and cannula (Add-a-Cath) and standard Foley catheter. A suprapubic catheter was inserted successfully in 63 patients. Overall there was a low incidence of urinary tract infection (4.3%) and the only significant catheter-related problem was suprapubic leakage of urine, which was self-limiting in all but one patient. Although there is little objective difference between the systems tested, we prefer the Add-a-Cath system for its simplicity and economy. This trial provides further support for the more frequent use of suprapubic catheters in general surgical practice.

Adolescent↗
PubMed1994

Anorectal physiology measurements are of no value in clinical practice. True or false?

This article examines whether there is any clinical value in anorectal physiology measurements. The function of the human rectum is poorly understood and the factors which affect function of the anal sphincters are complex. Several laboratories have reported results of anorectal physiology measurements, but there is extensive variation between normal values in different laboratories. It is argued that anorectal physiology measurements fail to meet the criteria of a useful clinical test: 1. It is not widely available to clinicians; 2. It is not possible to establish a reproducible normal range; 3. Abnormal measurements do not correlate with disease entities or explain symptoms; 4. The results are often unhelpful in diagnosis and management; 5. Clinical outcome after intervention does not correlate with alteration in the measurements obtained. On the other hand it can be argued that anorectal physiology measurements do provide information that assists in the management of conditions such as constipation, anismus, Hirschsprung's disease, faecal incontinence and tenesmus. Management based on biofeedback modification of physiological responses requires these techniques as part of the biofeedback system. There is evidence that this may be appropriate in anismus and solitary rectal ulcer syndrome. However, the assessment of these difficult conditions and the interpretation of the results are probably at present best confined to specialist units.

Anal Canal↗
PubMed1994

Pancreatic pseudocyst should be treated by surgical drainage.

This debate reviews the arguments in favour of surgical or non-surgical techniques for the management of pancreatic pseudocysts. Surgery provides definitive management and has a low risk of recurrence; pancreatic resection may be required to achieve this. Surgical treatment of pancreatic pseudocyst is safe, with little morbidity and low mortality, and surgical drainage allows biopsy of the cyst wall to exclude a cystic neoplasm of the pancreas. Percutaneous techniques have the advantage of low morbidity and mortality, with less discomfort to the patient than a surgical incision. In selected patients, a good result can be anticipated. The balance of the evidence suggests that both approaches are useful in different patients. Pseudocyst management should be tailored to each individual case.

Acute Disease↗
PubMed1993

Resection for adenocarcinoma of the body and tail of the pancreas.

Adenocarcinoma of the pancreatic body and tail often presents late and is widely regarded as incurable by surgical resection; long-term survivors are rare. Thirteen patients underwent left resection (n = 7) or total pancreatectomy (n = 6) in a consecutive series of 105 patients with carcinoma of the body or tail of the pancreas. Comparison was made with 17 patients with locally advanced or metastatic disease. Preoperative computed tomography predicted irresectable disease when a large perivascular lymph node mass was demonstrated. Preoperative angiography predicted irresectable disease when there was encasement or obliteration of the coeliac axis or its major branches, or of the superior mesenteric artery or vein. Splenic vessel involvement was sometimes compatible with resection. After resection, median survival was 13 (range 3-50) months, with a minimum follow-up of 2 years. Five patients survived more than 2 years, and three are still alive 30, 43 and 50 months after resection. Resection of carcinoma of the body or tail of the pancreas was possible in 12 per cent of patients and long-term survival was observed in some of these.

Adenocarcinoma↗
PubMed1993

Magnetic resonance imaging of the liver: current clinical applications.

Magnetic resonance imaging provides excellent anatomic depiction of the liver and important information about focal and diffuse diseases that affect this organ. In this report, the current clinical applications of magnetic resonance imaging of the liver in patients with known or suspected hepatic metastatic lesions, hepatocellular carcinoma, cavernous hemangiomas, focal fatty infiltration, focal nodular hyperplasia, hepatic adenoma, regenerative nodules in hepatic cirrhosis, or iron overload are reviewed, and the limitations of the technique are discussed.

Diagnosis, Differential↗