Interval nitrogen excretion and maintenance nitrogen requirements for parenteral nutrition in primates

This paper discusses a regression technique for determining maintenance nitrogen requirements in well-nourished primates (M fascicularis) on total parenteral nutrition. Animals were administered a continuous glucose infusion, and parenteral nitrogen intake was varied at constant time intervals in a random order (from 0 to 1 g nitrogen/kg/day). Interval nitrogen balance (intake minus urinary nitrogen output) was plotted against interval nitrogen intake. The x-intercept was defined as the maintenance nitrogen requirement. First, 24-h intervals were used at a nonprotein caloric intake of 85 kcal/kg/day (approximately 175% of primate resting energy expenditure) and the nutritional adequacy of the estimated requirement evaluated prospectively. Next, 8-h balance intervals were used and the maintenance nitrogen requirements predicted by this abbreviated technique were compared to those obtained using the longer method. Finally, the short-interval technique was repeated at two other levels of continuous glucose infusion (60 kcal/kg/day and 8 kcal/kg/day) and the effect on predicted nitrogen requirement examined. Maintenance parenteral nitrogen requirements for primates may be determined in 48 h using the abbreviated techniques.     

“Keyhole” method for accelerating imaging of contrast agent uptake

Magnetic resonance (MR) imaging methods with good spatial and contrast resolution are often too slow to follow the uptake of contrast agents with the desired temporal resolution. Imaging can be accelerated by skipping the acquisition of data normally taken with strong phase-encoding gradients, restricting acquisition to weak-gradient data only. If the usual procedure of substituting zeros for the missing data is followed, blurring results. Substituting instead reference data taken before or well after contrast agent injection reduces this problem. Volunteer and patient images obtained by using such reference data show that imaging can be usefully accelerated severalfold. Cortical and medullary regions of interest and whole kidney regions were studied, and both gradientand spin-echo images are shown. The method is believed to be compatible with other acceleration methods such as half-Fourier reconstruction and reading of more than one line of k space per excitation.     

Comparison of plain radiographs and coronal CT scans in infants and children with recurrent sinusitis

We performed a prospective study of 70 infants and children with recurrent sinusitis. We compared plain radiographs with coronal CT scans of the sinuses to determine if plain radiographs can be used to accurately diagnose and localize residual sinus disease amenable to endoscopic surgery. This residual disease is thought to be important in the pathogenesis of recurrences of sinusitis. The patients were taking antibiotics and were clinically well at the time of the two examinations (performed on the same day). Findings on slightly over 80% of the CT scans were abnormal. In about 75% of the patients, the findings on plain radiographs did not correlate with those on CT scans. About 45% of the patients had normal findings on plain radiographs of at least one sinus with an abnormality of that sinus shown on CT scans. Almost 35% of the patients had what was interpreted as an abnormality of at least one sinus on plain radiographs, but that sinus was normal on CT scans. Sinusitis in infants and children is often underdiagnosed or overdiagnosed on the basis of findings on plain radiographs of the sinuses. Plain radiographs cannot be used to determine the need for, or to guide, endoscopic surgery on the sinuses.     

Contact sensitivity in the pig

Following the application of a sensitizing dose of DNFB the afferent lymph draining the site becomes yellow due to the presence of dinitrophenylated proteins. Intralymphatic perfusion of such afferent lymph either whole or cell-free into recipients led to the development of contact sensitivity to DNFB in these animals. All of the OD³⁶⁰, due to the DNP group, in the afferent lymph was precipitable with trichloracetic acid and at least 90 per cent non-dialysable. Preliminary data indicate that the DNP is conjugated to eight or more proteins; however, the chemical nature of the carrier(s) responsible for the induction of contact sensitivity and whether it is derived from interstitial fluid or skin are unknown.

In a second group of experiments, in vitro conjugation of DNP to autologous lymph node cells and subsequent infusion via the afferent lymphatic, induced contact sensitivity against DNFB, and furthermore, very small amounts of DNP administered in this manner were required. In contrast 0.1 μmol of DNP coupled to RBCs did not induce contact sensitivity in five of six experiments.

These results indicate that one mechanism leading to the induction of contact sensitivity to DNFB in the pig is by direct conjugation of this chemical to the specific carrier which subsequently passes to the regional lymph node via the afferent lymph. A second possible mechanism is that DNP at the peripheral site conjugates directly to WBCs which function as carriers. Although we as yet have no evidence that this second possibility occurs in vivo, it remains attractive because of the minute amounts of DNP which can induce contact sensitivity after coupling to lymph node cells in vitro.

     

Vocational services for traumatic brain injury: treatment definition and diversity within model systems of care

OBJECTIVE: To examine characteristics and diversity among vocational treatment services in model programs for traumatic brain injury (TBI) rehabilitation. SETTING: Vocational or postacute treatment components of 16 TBI Model System (TBIMS) centers. PARTICIPANTS: Vocational director/coordinator from each TBIMS surveyed in semistructured phone interview. MEASURE: Survey of vocational services for people with TBI, with about 100 closed and open-ended questions on vocational assessments; pre- and postjob placement treatments; program philosophies; funding; and integration of cognitive, behavioral, family, and medical rehabilitation interventions. RESULTS: Great diversity was found among the vocational services of the 16 TBIMS. Programs fell into 3 clusters emphasizing medical rehabilitation services, supported employment, or a combination of these with an emphasis on case management. Job coaching was identified as a key intervention, but there was great variability in intensity, availability, and funding of coaching services. CONCLUSION: Diversity in vocational services appears related to funding differences and "parallel evolution" rather than strong treatment philosophy or scientific evidence base. Multicenter research on effectiveness or establishment of best practices in vocational rehabilitation after TBI must deal with substantial existing variability in treatment models and specific interventions, and must examine the relationship of treatment variations to case-mix factors.