Racemization of α-amino acid esters by aliphatic ketones in the presence of carboxylic acids

Amino acid esters are racemized by dissolution in a mixture of aliphatic ketones and carboxylic acids. The racemization rate mainly depends on the structure of the amino acid and on the kind of ketone and carboxylic acid used, the best racemizing medium being acetone containing 15% acetic acid. The mechanism of the racemization and the practical consequences of this study in the optical resolution field are discussed.     

Neck neoplasms: MR imaging. Part I. Initial evaluation

Untreated neoplasms of the neck (tumors of the oropharynx, supraglottic area, carotid body, and thyroid, in addition to malignant lymphadenopathy) were evaluated in 23 patients with magnetic resonance (MR) imaging. The results were compared with computed tomographic (CT) scans in 20 patients. Contrast between tumor and fat was best on relatively T1-weighted images (500/30-35 [TR msec/TE msec]), whereas separation of tumor and muscle was best with relatively T2-weighted pulse sequences (1,500/90). Balanced images (1,500/30-35) provided best overall image quality and best demonstrated vascular anatomy. MR imaging was usually superior to CT in showing the relationship of tumor mass to muscle. MR imaging and contrast material-enhanced CT were equivalent in most patients in defining vascular anatomy, but MR imaging was superior when intravenous contrast material was not administered. However, CT was more helpful in showing bone and cartilage anatomy, and in some patients CT also was better in showing airway abnormalities. Despite these limitations, MR imaging is a promising imaging technique for studying neoplasms of the neck.     

Assessment of behavioral mechanisms maintaining encopresis: Virginia Encopresis-Constipation Apperception Test

OBJECTIVE: To develop and test a scale for parent and child, evaluating theoretical and clinical parameters relevant to children with encopresis. Encopretic children were hypothesized to have more bowel-specific, but not more generic, psychological problems, as compared with nonsymptomatic control children. In addition, mothers were also believed to be more discerning than children. METHODS: The Virginia Encopresis-Constipation Apperception Test (VECAT) consists of 9 pairs of bowel-specific and 9 parallel generic drawings. Respondents selected the picture in each pair that best described them/their child. It was administered to encopretic children (N = 87), nonsymptomatic siblings (N = 27), and nonsymptomatic nonsiblings (N = 35). The mothers of all the participants also completed the VECAT. Encopretic children were retested 6 and 12 months posttreatment with Enhanced Toilet Training. RESULTS: The VECAT demonstrated good test-retest reliability and internal consistency. Encopretic children and their mothers reported more bowel-specific, but not more generic, problems. Bowel-specific scores improved significantly posttreatment only for those patients who demonstrated significant symptom improvement. Mothers were significantly more discerning than children. CONCLUSION: The VECAT is a reliable, valid, discriminating, and sensitive test. Bowel-specific problems appear to best differentiate children with and without encopresis.     

Endoscopic SIS injection into the lower oesophageal sphincter in dogs

Aim To determine the usefulness of endoscopically-delivered small intestinal submucosa (SIS) as a scaffold in enhancing the lower oesophageal sphincter (LOS) pressures. Methods Six dogs were endoscopically injected - four with the SIS and two with its glycerin carrier. Manometry was performed prior to injection and every four weeks post-op. Results Adequate and site correct injections were made in four dogs. In one dog, significant augmentation of pressures were obtained at four weeks. None had significant changes in pressure at eight weeks, differences in length at either four or eight weeks or significant differences in the thickness of the examined layers. Four of the six had capillary cushions on pathological examination. The dog injected with the carrier had a loose and disorganised collection, while the others were well organised. Conclusion SIS is a biologically compatible material. Lack of an animal model for gastro-oesophageal reflux disease (GORD) makes determining the ability of injections of SIS to combat reflux problematic.     

Low-dose flying spot digital radiography of the chest: sensitivity studies

Standard film examinations of the chest were compared with low-dose flying spot digital radiographic examinations obtained with a prototype unit in 174 patients. Analysis of pooled data from a double-blind study of 120 patients showed that film was more sensitive than digital images in the detection of pulmonary parenchymal abnormalities, that is, abnormal opacities, atelectasis, scar, and interstitial lung disease (P less than .05). Analysis of pooled data from a side-by-side study of 54 patients showed that the digital images were more sensitive than film in the detection of normal mediastinal and pleural soft-tissue contours, including the azygoesophageal recess, paraspinal line, and vertebral disk spaces (P less than .05). However, film was more sensitive than digital images in the detection of abnormalities of the lung, including scar, interstitial lung disease, septal lines, and the presence of vascular catheters (P less than .05). These findings suggest that low-dose flying spot digital radiography of the chest, as performed with this specific prototype unit, is not adequate to replace film in the detection of abnormalities of the lung parenchyma.     

Computed tomographic studies of the painful abdomen

Abdominal CT scans were reviewed in a series of 53 patients who had abdominal pain without objective physical, radiographic, or laboratory abnormalities. Forty patients presented with abdominal pain alone, while the remaining patients had abdominal pain associated with nausea, vomiting, or mild weight loss. Abdominal CT scans in all patients were interpreted as normal. In all but one patient, the final diagnosis was an insignificant benign condition. One patient had a pancreatic carcinoma discovered at surgery one month after the CT scan was obtained. The patients were followed up for 6 to 12 months to confirm absence of significant disease. Our analysis suggests a very low yield from abdominal CT in patients with abdominal pain and no other objective findings.     

Optimal double-contrast visualization of the posteriorly directed duodenal bulb

The posteriorly directed duodenal bulb can be difficult to demonstrate because of the overlapping gastric antrum. A technique is described for displacing the antrum from the bulb while simultaneously distending the barium-coated duodenal bulb with air.