The measurement of proton stopping power using proton-cone-beam computed tomography.

A cone-beam computed tomography (CT) system utilizing a proton beam has been developed and tested. The cone beam is produced by scattering a 160 MeV proton beam with a modifier that results in a signal in the detector system, which decreases monotonically with depth in the medium. The detector system consists of a Gd2O2S:Tb intensifying screen viewed by a cooled CCD camera. The Feldkamp-Davis-Kress cone-beam reconstruction algorithm is applied to the projection data to obtain the CT voxel data representing proton stopping power. The system described is capable of reconstructing data over a 16 x 16 x 16 cm3 volume into 512 x 512 x 512 voxels. A spatial and contrast resolution phantom was scanned to determine the performance of the system. Spatial resolution is significantly degraded by multiple Coulomb scattering effects. Comparison of the reconstructed proton CT values with x-ray CT derived proton stopping powers shows that there may be some advantage to obtaining stopping powers directly with proton CT. The system described suggests a possible practical method of obtaining this measurement in vivo.

Characterization of human endotoxin lipopolysaccharide receptor CD14 expression in transgenic mice.

CD14 is a major receptor for the bacterial endotoxin LPS. Since CD14 is specifically and highly expressed on the surface of monocytic cells, it has been used as a monocyte/macrophage differentiation marker. To identify elements that are critical for the direction of the tissue-specific expression of CD14, an 80-kb genomic DNA fragment containing the coding region of the CD14 gene, as well as a considerable amount of both upstream and downstream sequence, was used to generate transgenic mice. The analysis of mice from six different founder lines demonstrated that this genomic DNA fragment was sufficient to direct human CD14 gene expression in a monocyte-specific manner among hematopoietic cells. Furthermore, the data lead us to a new finding that CD14 is highly expressed in the human liver, a primary organ involved in the acute phase response. These transgenic mice provide a useful model to analyze the biological function of human CD14.

Mantle irradiation alone for selected patients with laparotomy-staged IA to IIA Hodgkin's disease: preliminary results of a prospective trial.

PURPOSE: To determine the feasibility of omitting prophylactic paraaortic irradiation in selected patients with laparotomy-staged (pathologically staged [PS]) IA to IIA Hodgkin's disease. PATIENTS AND METHODS: We initiated a prospective single-arm trial in October 1988 to study the role of mantle irradiation alone in selected PS IA to IIA patients with Hodgkin's disease. A total of 37 patients have been entered onto this trial. Entrance criteria included nodular sclerosis (NS) or lymphocyte predominance (LP) histology, absence of B symptoms, disease limited above the carina, and a negative laparotomy. Results of treatment of 23 patients in the prospective trial, monitored off treatment for > or = 1 year, are presented. Twenty-three additional PS IA to IIA patients, treated with mantle irradiation alone from 1970 to 1987, were analyzed as a comparison group. The median follow-up durations were 32 and 113 months, respectively, for the two groups. RESULTS: The 4-year actuarial rates of freedom from relapse and overall survival are 83% and 100%, respectively, for the prospective trial. The 10-year actuarial rates of freedom from relapse and overall survival are 83% and 89%, respectively, for retrospectively studied patients. There have been five recurrences among 46 patients who received mantle irradiation alone, all with a component of relapse below the diaphragm. CONCLUSION: These early results support the use of mantle irradiation alone in selected PS IA to IIA patients with NS or LP histology. Relapses, although rare, have occurred predominantly below the diaphragm. This suggests the need for continued long-term surveillance of abdominal and pelvic nodes in this group of treated patients.

Selective targeting of gene products with the megakaryocyte platelet factor 4 promoter.

We have used the 1.1 kilobases of the 5' upstream region of the platelet factor four (PF4) gene coupled to the prokaryotic beta-galactosidase gene to generate two lines of transgenic mice that express this construct. Studies of blood, bone marrow, spleen, and thymus reveal that platelets are the only circulating blood cells and megakaryocytes are the only hematopoietic precursor cells that possess the prokaryotic enzyme. The lack of transgene expression in brain, heart, intestine, kidney, liver, lung, and skeletal muscle was established by in situ staining of tissue sections as well as kinetic assay of tissue homogenates. These data suggest that this domain of the PF4 promoter contains most, if not all, of the tissue-specific region of the gene. Unexpectedly, the adrenal gland exhibits approximately 2% of the levels of beta-galactosidase possessed by megakaryocytes and the distribution of the prokaryotic enzyme corresponds to the location of mineralocorticoid-secreting cells. This result implies that either the PF4 gene is transcribed at low levels in specialized adrenal cells or that these specialized endocrine cells possess trans-acting factors similar to those that control the megakaryocyte promoter. The selective high-level expression of transgenes linked to the PF4 promoter should allow us to augment or suppress the in vivo levels of critical components in megakaryocytes and platelets and subsequently ascertain the effects of these modifications.

The tumor promoter phorbol 12-myristate 13-acetate induces a program of altered gene expression similar to that induced by platelet-derived growth factor and transforming oncogenes.

Treatment of mouse NIH 3T3 cells with the phorbol ester tumor promoter, phorbol 12-myristate 13-acetate, results in altered transcription of several genes as measured in nuclear run-off experiments. The first set of genes, whose altered transcription occurs rapidly in the absence of protein synthesis, is typified by induction of c-myc and c-fos and decreased transcription of alpha 2 type I procollagen. This work demonstrates the existence of a second class of genes whose rapidly increased transcription requires prior protein synthesis, which is represented by the gene encoding a secreted lysosomal protein, MEP. Similar induction of MEP RNA is seen after treatment with platelet-derived growth factor or transformation with Kirsten sarcoma virus.

Ultrasound demonstration of valvulae conniventes in small-bowel obstruction. A case report.

Plain radiographs may on occasion be misleading in patients with intestinal obstruction, owing to the presence of fluid-filled loops of bowel. Ultrasound examination, by demonstrating fluid-filled loops, can provide a definitive diagnosis in such cases. A case report is presented.

The reflux gastroesophageal polyp.

An inflammatory polyp at the gastroesophageal junction due to gastroesophageal reflux is a rare documented finding and its appearance on x-ray has only recently been described. A recently encountered case whose only symptom was of minor episodes of hematemeses is described and the literature is reviewed.

Ultrasound and barium study in the evaluation of upper abdominal masses.

Numerous radiological procedures are now available for investigation of upper abdominal masses of uncertain aetiology; however, certain limitations and pitfalls are associated with these procedures. It is suggested that the initial use of ultrasound and barium studies would frequently provide either a definite diagnosis or lead to the next appropriate line of investigation. The importance of not omitting the barium study is stressed.

Fine-needle percutaneous cholangiography followed by drainage of the biliary system: An initial report.

Fine-needle percutaneous transhepatic cholangiography has gained popularity for investigating patients with obstructive jaundice, after which percutaneous drainage of the biliary tree is frequently carried out. The technique is described and the results from 10 patients in whom the procedure was carried out are discussed.

The 'riding' ulcer: A report of 3 cases.

Hiatal hernia with ulceration at the level of the diaphragm is a well-recognized and not uncommon condition. These ulcers may be simple gastric ulcers in patients who coincidentally have a hiatal hernia, or they may be related to trauma of the stomach against the diaphragm. They are not always readily detected on barium study. The clinical and radiological features in 3 recent cases are described, together with a brief review of the literature.

Gastro-intestinal haemorrhage associated with leukaemic infiltration of the stomach: A report of 2 cases.

Two cases of leukaemic infiltration of the stomach are presented. In both patients the dominant presenting sign was gastro-intestinal bleeding. The clinical, radiological and pathological findings are presented together with a brief review of the literature.

High frequency of mutation to tubercidin resistance in CHO cells.

The acquisition of high-level resistance to tubercidin (an adenosine analog) in CHO cells occurs in a single step at high frequency (10(-3) to 10(-4)) without mutagenesis. Analysis of a large number of independent mutants by a fluctuation test (Luria and Delbruk, 1943) indicates that they arise independently of the selection medium and all fall into the same complementation group. All mutants tested lack detectable adenosine kinase activity. An analysis of hybrids between mutant and wild-type cells indicates that resistance to tubercidin is a recessive marker which segregates as would be expected if it were a haploid locus in the parental CHO cell. Resistance to tubercidin is not linked to the X chromosome in CHO cells and appears to occur at much lower frequency in primary Chinese hamster cells and other cultured cell lines.

Radiological changes of reflux oesophagitis.

Early changes in reflux oesophagitis are difficult to assess on radiological criteria (Torrance, 1973). The later manifestations, particularly with stricture formation, are best assessed by barium swallow. Apart from stricture formation, marked reflux oesophagitis with coarsened folds may lead to a mistaken diagnosis of varices or carcinoma. The various radiological appearances that have been encountered are described.

Metastatic breast carcinoma presenting as obstructive jaundice. A report of 3 cases.

Three patients who developed obstructive jaundice after mastectomy for carcinoma of the breast are presented. Prognosis is invariably poor as widespread metastases are usually present at the time of presentation. The pathogenesis, investigations and clinical significance are discussed.

Choledochocele. A case report.

A case of a young man with a choledochocele is presented. The entity is rare and symptoms are usually nonspecific. Pre-operative diagnosis is often not made but is usually possible provided both barium study and cholangiography are performed. The clinical presentation and diagnosis are discussed.

Caecal bascule--a potential clinical and radiological pitfall. Case reports.

Caecal volvulus is usually associated with a twisted caecum, seen to occupy the umbilical area or left hypochondrium on radiography. Caecal bascule refers to the form of volvulus in which the distended caecum is situated within the pelvis. The caecal bascule type of obstruction is uncommon, and clinical and radiological appearances may be confusing. Two cases are presented and the incidence, pathogenesis and radiological features are discussed.

Correlation of the site of obstruction with the lesion by fine-needle percutaneous cholangiography.

The use of fine-needle percutaneous transhepatic cholangiography is becoming a standard procedure for investigating jaundiced patients undergoing surgery. The results of this procedure in 40 patients investigated at the Johannesburg Hospital show the importance of correlating the site of obstruction with the nature of the lesion.

Pneumatosis coli secondary to colonic obstruction. A case report.

A case of pneumatosis coli of the caecum and ascending colon with a closed loop obstruction secondary to carcinoma of the descending colon is presented. The caecum was grossly distended and impending rupture was diagnosed. It is postulated that complete transmural rupture of the caecum was prevented by partial decompression of caecal air into the bowel wall.