Expression of OB receptor splice variants during prenatal development of the mouse

In adult animals, signaling through the leptin receptor (OB-R) has been shown to play a critical role in fat metabolism. However, it is not known when these receptors are first expressed and what their role may be during embryonic development. To date, at least 6 splice variants of the OB-R have been identified. Although the function of each of these individual splice variants are unknown, only one of them, ob-rL ,encodes a receptor with a long intracellular domain that is implicated in OB-R signaling. In this study we have used in situ hybridization to examine the localization of OB-R splice variants during embryonic development of C57B1/6J mice. Using a probe, ob-r, that recognizes all of the splice variants, ob-r mRNA was found to be distributed in developing bone, mesenchyme, notochord and liver. In addition, epithelial structures including leptomeninges, choroid plexi and hair follicles also expressed ob-r. No ob-r mRNA was detected in the CNS. ob-rL, expression was only detected in notochord, bone and mesenchyme. The differential expression of these two mRNA isoforms suggests that the extracellular and intracellular domains of the OB receptor perform different biological functions.

Postnatal neuronal proliferation in mice lacking Ink4d and Kip1 inhibitors of cyclin-dependent kinases

Development of the central nervous system requires proliferation of neuronal and glial cell precursors followed by their subsequent differentiation in a highly coordinated manner. The timing of neuronal cell cycle exit and differentiation is likely to be regulated in part by inhibitors of cyclin-dependent kinases. Overlapping and sustained patterns of expression of two cyclin-dependent kinases, p19(Ink4d) and p27(Kip1), in postmitotic brain cells suggested that these proteins may be important in actively repressing neuronal proliferation. Animals derived from crosses of Ink4d- null with Kip1-null mice exhibited bradykinesia, proprioceptive abnormalities, and seizures, and died at about 18 days after birth. Metabolic labeling of live animals with bromodeoxyuridine at postnatal days 14 and 18, combined with immunolabeling of neuronal markers, showed that subpopulations of central nervous system neurons were proliferating in all parts of the brain, including normally dormant cells of the hippocampus, cortex, hypothalamus, pons, and brainstem. These cells also expressed phosphorylated histone H3, a marker for late G(2) and M-phase progression, indicating that neurons were dividing after they had migrated to their final positions in the brain. Increased proliferation was balanced by cell death, resulting in no gross changes in the cytoarchitecture of the brains of these mice. Therefore, p19(Ink4d) and p27(Kip1) cooperate to maintain differentiated neurons in a quiescent state that is potentially reversible.

Changes in the numbers of neurons and astrocytes during the postnatal development of the rat inferior olive

In the developing nervous system, cell death is an important component of refining axonal projections. In the developing rat inferior olive, previous studies have demonstrated cell death as temporally incongruent with both initial axon-target interactions and subsequent axon collateral regression. Furthermore, these studies identified a late rise in neuron numbers that is concurrent with climbing fibre regression. As axonal regression has not previously been associated with increasing neuron numbers, and since immature neurons and glia have similar morphological characteristics, it was decided to reassess the timing of cell death within the inferior olive in animals in which neurons and glia had been differentially stained. Glia were identified by the presence of glial cytoskeletal proteins, S100, or glial fibrillary acidic protein, and stereological counts were made of both neurons and glia in the inferior olive from rats of ages 0, 5, 10, 15, and 30 days. The number of inferior olivary neurons was approximately 22,000 between birth and day 10, which decreased to about 17,500 by day 30 (P<0.05). In contrast, the number of glia rose from about 5,000 at birth to approximately 15,000 by day 10 (P<0.001), after which there was no further increase. The changes in neurons and glia caused the neuron-to-glia ratio to fall to approximately 1.5 by the time of functional maturation within the olive. These results confirm that there is neuronal death in the inferior olive but that it is temporally correlated with both climbing fibre regression and functional maturation of the olivocerebellar projection.

Sonographic findings in testicular sarcoidosis simulating malignant nodule

Testicular involvement by sarcoidosis is rare. We report a case of a patient with known sarcoid who had a unilateral testicular nodule with apparent capsular invasion on sonography. The epididymis was normal on both sides. Despite these atypical features, pathology showed the nodule to be a sarcoid granuloma. In patients with sarcoidosis, the differential diagnosis of an intratesticular mass should include testicular involvement by sarcoid.

Microtubule assembly is regulated by externally applied strain in cultured smooth muscle cells

Mechanical forces clearly regulate the development and phenotype of a variety of tissues and cultured cells. However, it is not clear how mechanical information is transduced intracellularly to alter cellular function. Thermodynamic modeling predicts that mechanical forces influence microtubule assembly, and hence suggest microtubules as one potential cytoskeletal target for mechanical signals. In this study, the assembly of microtubules was analyzed in rat aortic smooth muscle cells cultured on silicon rubber substrates exposed to step increases in applied strain. Cytoskeletal and total cellular protein fractions were extracted from the cells following application of the external strain, and tubulin levels were quantified biochemically via a competitive ELISA and western blotting using bovine brain tubulin as a standard. In the first set of experiments, smooth muscle cells were subjected to a step-increase in strain and the distribution of tubulin between monomeric, polymeric, and total cellular pools was followed with time. Microtubule mass increased rapidly following application of the strain, with a statistically significant increase (P<0.05) in microtubule mass from 373+/-32 pg/cell (t=0) to 514+/-30 pg/cell (t=15 minutes). In parallel, the amount of soluble tubulin decreased approximately fivefold. The microtubule mass decreased after 1 hour to a value of 437+/-24 pg/cell. In the second set of experiments, smooth muscle cells were subjected to increasing doses of externally applied strain using a custom-built strain device. Monomeric, polymeric, and total tubulin fractions were extracted after 15 minutes of applied strain and quantified as for the earlier experiments. Microtubule mass increased with increasing strain while total cellular tubulin levels remained essentially constant at all strain levels. These findings are consistent with a thermodynamic model which predicts that microtubule assembly is promoted as a cell is stretched and compressional loads on the microtubules are presumably relieved. Furthermore, these data suggest microtubules are a potential target for translating changes in externally applied mechanical stimuli to alterations in cellular phenotype.

The glucose/insulin system and vitamin C: implications in insulin-dependent diabetes mellitus

The cellular uptake of vitamin C (ascorbic acid, ASC) is promoted by insulin and inhibited by hyperglycemia. If a rise in plasma ASC is uncoupled from insulin replacement in insulin-dependent diabetes mellitus (IDDM) then the degree of hyperglycemia could account for "tissue scurvy" in IDDM. Leukocyte ASC is lower in IDDMs compared with nondiabetics when vitamin C consumption is adequate and our data suggest that this is a variable component of the pathophysiology of IDDM. The complications of diabetes mellitus are believed to result from either the intracellular accumulation of sorbitol or the nonenzymatic glycoxidation of proteins or both. With respect to the abnormal cellular accumulation of sorbitol, vitamin C supplementation has been shown to be effective in several studies of adults with diabetes; the situation regarding the prevention of protein glycoxidations by supplementation is presently unclear. The roles of ASC as an aldose reductase inhibitor and a water soluble antioxidant in body fluids are potentially very important as adjuncts to tight glycemic control in the management of diabetes. Tissue saturation and maximal physiologic function in IDDM may require supplemental vitamin C intake.

Micronutrients as nutriceutical interventions in diabetes mellitus

Hyperglycemia portends chronic complications in insulin-dependent diabetes mellitus (IDDM) and substantial benefits are associated with "tight" glycemic control. Other interventions should either enhance glycemic control per se or add benefit to an established degree of glycemic control. Several micronutrients enhance insulin action and others offer promise in countering the untoward consequences of hyperglycemia. Supplements of micronutrients including the vitamins niacin (as niacinamide), C and E and the minerals zinc, chromium and vanadium have been studied. For the purpose of this review, the term "nutriceutic" refers to supplementation on the order of 2 to 10 times the RDA for which a benefit is linked to a mechanism of action. Benefits associated with "nutriceutic" supplementation are reported in small trials for vitamins C and E and these supplements are safe and affordable from food or tablet sources. A dietary strategy adding 200-600 mg of vitamin C and 100 IU of vitamin E to a healthy dietary pattern is worthy of consideration as an intervention for individuals with IDDM.

Physiologic hypoalbuminemia is well tolerated by severely burned children

BACKGROUND

Physiologic hypoalbuminemia, defined as a plasma albumin (pl-ALB) of 1.0 to 2.5 g/dL, is a component of the injury response. A consensus on the need for albumin supplementation in this setting is lacking.

METHODS

We examined 27 consecutive children (age, 7 +/- 6 years) with > 40% body surface burns (mean, 59 +/- 18%) during their initial 4 weeks of care. Patients were managed with an albumin-supplementation protocol that tolerated profound physiologic hypoalbuminemia. Intravenous albumin was administered by infusion of 1 to 2 g/kg/d when pl-ALB fell below 1.0 g/dL, or below 1.5 g/dL in the presence of enteral feeding intolerance or pulmonary dysfunction. Supplementation was stopped when pl-ALB reached 2.0 g/dL.

RESULTS

Mean pl-ALB was 1.7 g/dL overall. Infusion for pl-ALB < 1.0 g/dL was needed for 70% (n = 19) of the patients. Profound physiologic hypoalbuminemia was constant, that is, mean weekly pl-ALB never exceed 2.5 g/dL in any patient. Mean plasma globulin rose during the 4 week period from 2.3 +/- 0.1 at week 1 to 3.1 +/- 0.1 at week 4. Diarrhea was negligible (19 of 756 patient days), nasogastric feedings were well tolerated, PaO2/FiO2 ratios remained well above 150, wounds healed satisfactorily, and all children survived and have been discharged home.

CONCLUSIONS

Profound physiologic hypoalbuminemia (pl-ALB of 1.0-2.5 g/dL) does not have adverse effects on pulmonary or gut function, wound healing, or outcome in severely burned children, perhaps because of a compensatory increase in acute-phase proteins reflected in plasma globulin.

Energy and protein provisions for thermally injured children revisited: an outcome-based approach for determining requirements

Energy and protein provisions for adequate wound healing and weight maintenance were examined among severely burned children. Actual intakes were documented for 27 patients admitted with a more than 40% total body surface area burn. Mean energy intake over the 4-week study period averaged 140% of the predicted basal metabolic rate (PBMR), and mean protein intake was 2.8 +/- 0.2 grams per kilogram daily. Wound healing progressed satisfactorily in all patients; at 4 weeks, the open wound area (% open) was 20% or less in 22 patients. Average weight at discharge was 88% +/- 2.6% of ideal body weight. Discharge weights were significantly higher (p < 0.05) among patients whose energy intake exceeded PBMR x 1.7 for at least 1 of the study weeks. We suggest that energy intakes approximating PBMR x 1.2 with a minimum of 3 grams of protein per kilogram will support adequate wound healing, whereas higher energy provisions (PBMR x 1.7) will enhance weight status.

Low ceruloplasmin levels during recovery from major burn injury: influence of open wound size and copper supplementation

Copper (Cu) status is often judged by the plasma level of its chief transport protein, ceruloplasmin (Cp). Only copper deficiency and heredity are known to decrease circulating Cp. Cp is an acute-phase responsive protein in trauma and it is also induced by Cu supplementation. Despite this, plasma concentrations of Cp remain low during the acute recovery from major burn injury. The high provision of vitamin C typically used in burn patients may influence these observations when an indirect oxidase activity assay is used. We employed a radial immunodiffusion (RID) assay specific for the Cp protein as well as an indirect oxidase assay for Cp in a series of 11 burned children who were supplemented with both Cu and vitamin C, either enterally or parenterally. Our findings confirm that low Cp is a characteristic of the acute recovery from major burns. The oxidase assay is shown to be valid for very low Cp levels even during high vitamin C provision. When these data are combined with our previously reported series, a strong relationship between the size of the open wound area and the amount of circulating Cp is demonstrated. Copper supplementation by either the enteral or parenteral routes is only marginally successful in restoring Cp toward normal levels.

Body composition and nutrition support in pediatrics: what to defend and how soon to begin

Specialized nutrition support is initiated during hospital care on the assumption that sparing the mobilization of body energy reserves is advantageous to recovery. The combined effects of disease and undernutrition on body cell mass, organ function, immune responsiveness, and wound healing are well documented in adults. Children cannot survive a fast as long as adults because of their lesser stores of energy substrates relative to the rate of energy expenditure. The present contribution attempts to estimate the rates of compositional losses for infants and prepubertal children on the basis of available data and reasonable metabolic assumptions. The lesson that emerges from this exercise is one of a very critical need for the early initiation of nutrition support for infants and children. The analysis suggests that an acute risk of protein depletion exists for children of all ages. Especially for infants, the empirical wisdom that "the absence of evidence is not evidence of absence" should be invoked to support early nutrition intervention. This work is submitted for critical review and revision to establish a consensus on the timeline of pediatric morbidity or mortality from semistarvation or starvation.

Hyperzincuria in individuals with insulin-dependent diabetes mellitus: concurrent zinc status and the effect of high-dose zinc supplementation

The urinary excretion of zinc in individuals with insulin-dependent diabetes mellitus (IDDM) is approximately doubled. In the absence of a compensatory mechanism, this hyperzincuria should induce a deficient or marginal Zn status. We examined parameters of Zn status in plasma and in blood cells with respect to urinary Zn losses and Zn supplementation. We measured Zn levels in the urine, plasma, and erythrocytes of 14 IDDM subjects and 15 nondiabetics who kept dietary records for 3 consecutive days. Subsequently, six IDDM subjects and seven nondiabetics were supplemented with 50 mg Zn daily for 28 days. We measured the above parameters, as well as mononuclear leukocyte Zn (MNL-Zn) and the plasma subfraction of albumin-bound Zn (alb-Zn). The total plasma Zn-binding capacity was also assessed. Plasma copper and erythrocyte Cu were monitored as indicators of potential Zn toxicity. Individuals with IDDM displayed the expected hyperzincuria, but had normal blood Zn parameters. Zincuria increased by a similar amount in both groups during supplementation, as did the MNL-Zn content. However, erythrocyte Zn (e-Zn) was refractory, so a trend toward lower e-Zn among IDDM subjects persisted during Zn supplementation. Hemoglobin A1c (HbA1c) increased markedly in the Zn-supplemented IDDM group. Despite their chronic hyperzincuria, individuals with IDDM appear not to be Zn-deficient. Large-dose Zn supplementation increases MNL-Zn and induces an undesirable elevation of HbA1c in all individuals. This is especially disconcerting for those with IDDM, and may reflect an exacerbation of a chronic "Zn diabetes." These data suggest a potential for toxicity from large-dose Zn supplementation.

Vitamin C: an aldose reductase inhibitor that normalizes erythrocyte sorbitol in insulin-dependent diabetes mellitus

OBJECTIVE

Diabetic hyperglycemia promotes sorbitol production from glucose via aldose reductase. Since the intracellular accumulation of sorbitol, or its sequelae, are postulated to contribute to the progression of chronic diabetic complications, aldose reductase inhibitors (ARI) offer therapeutic promise. Others have shown that vitamin C at pharmacologic doses decreases erythrocyte (RBC) sorbitol. We examined whether smaller, physiologic doses of vitamin C were also effective in individuals with insulin-dependent diabetes mellitus (IDDM) and whether vitamin C was an ARI in vitro.

METHODS

Vitamin C supplements (100 or 600 mg) were taken daily for 58 days by young adults with IDDM and nondiabetic adults in an otherwise free-living design. Diabetic control was monitored by fasting plasma glucose, glycosylated hemoglobin, and glycosuria and was moderate to poor throughout the study. RBC sorbitol was measured at baseline and again at 30 and 58 days. Three-day dietary records and 24-hour urine collections were performed for each sampling day.

RESULTS

RBC sorbitol levels were significantly elevated in IDDMs, on average doubled, despite their more than adequate dietary intakes of vitamin C and normal plasma concentrations. Vitamin C supplementation at either dose normalized the RBC sorbitol in IDDMs within 30 days. This correction of sorbitol accumulation was independent of changes in diabetic control. Furthermore, our in vitro studies show that ascorbic acid inhibited aldose reductase activity.

CONCLUSIONS

Vitamin C supplementation is effective in reducing sorbitol accumulation in the erythrocytes of diabetics. Given its tissue distribution and low toxicity, we suggest a superiority for vitamin C over pharmaceutic ARIs.

Effects of chromium picolinate supplementation on body composition, strength, and urinary chromium loss in football players

The effects of 9 weeks of daily chromium supplementation (200 microgram Cr as picolinate) were investigated in a double-blind design in football players during spring training. Testing was done pre-, mid-, and postsupplementation on the following criterion measures: urinary chromium excretion, girth and skinfold measures, percent body fat and lean body mass, and isometric and dynamic strength. With the exception of 2 variables (of 65 variables analyzed), no significant group by trials interactions were found (based on a repeated measures ANOVA). The two exceptions were unrelated and inconsequential. For 27 of the 38 subjects, average urinary chromium loss at pre was 0.36 microgram/24 hr, whereas it was undetectable (<0.1 microgram/24 hr) for 10 subjects and excessive in 1 subject (2.4 micrograms/24 hr). Subjects receiving chromium supplements demonstrated urinary chromium losses five times greater than those in the placebo group at mid and post. Chromium picolinate supplementation was ineffective in bringing about changes in body composition or strength during a program of intensive weight-lifting training.

Burn severity, copper dose, and plasma ceruloplasmin in burned children during total parenteral nutrition

Copper (Cu) is an essential nutrient with known metabolic roles in wound healing. Ceruloplasmin (CP), the primary Cu-transport protein, responds as an acute-phase reactive protein after trauma. However, for severe burn trauma, this response is absent in the early catabolic phase despite Cu provision. We report data for 14 severely burned children receiving Cu in total parenteral nutrition (TPN-Cu) ranging from 7 to 26 micrograms Cu.kg-1 x day-1. All patients manifested low plasma levels of CP. The reduction in CP reflected burn severity but also appeared to be dependent on the Cu dose. Increasing Cu supplementation to improve CP raises a concern for hepatotoxicity, which is accompanied by an elevation in the plasma nonceruloplasmin Cu (nonCP-Cu). The calculated plasma nonCP-Cu in our series is consistent with a lack of increased risk and suggests that TPN-Cu at the general pediatric guideline of 20 micrograms.kg-1 x day-1 is safe and reasonable for severely burned children. Cu supplementation > 20 micrograms/kg may be beneficial; however, monitoring of both CP and total Cu should continue as standard practice in the management of these patients.

Evaporative water losses through a temporary wound dressing under simulated wound conditions

Patients with burns lose large amounts of water through evaporation from open wounds. Because the wound covering is the first line of defense for maintenance of body fluid balance in these patients, quantification of the evaporative water loss through wound coverings at the bedside would improve the accuracy of estimations of body water loss. The present experiment evaluates the use of a small ventilated capsule system automated with miniature resistance-type dew-point sensors for measurement of evaporative water loss through biologic dressings under simulated wound conditions. Evaporative water loss from wounds was simulated by pilocarpine-induced profuse sweating on the forearm. Evaporative water loss through uncovered skin was compared with that of skin covered with commercially available temporary wound dressings. Compared with an adjacent unstimulated area, forearm dew-point temperature in the capsule (Tcdp) and sweat rate increased immediately after pilocarpine exposure and remained significantly elevated and relatively constant for an additional 60 minutes. Evaporative water loss of the forearm was 29 +/- 4.8 gm/m2/hr (mean +/- SE) at baseline and rose significantly to 275 +/- 18.2 gm/m2/hr after pilocarpine exposure. The pilocarpine-stimulated sweat rate and Tcdp at neutral conditions were similar to those obtained from walking on a treadmill for 60 minutes in a 30 degrees C room. Compared with pilocarpine-induced evaporative water loss of the uncovered skin, temporary wound dressings significantly reduced evaporative water loss by 40% to 60%. No significant differences were observed between varieties of temporary wound dressings differing in thickness and/or porosity.(ABSTRACT TRUNCATED AT 250 WORDS)

A semiautomatic device for feeding liquid milk-replacer diets to infant pigs

We describe the design and use of a device that enables the semiautomatic feeding of various quantities of liquid, milk-replacer diet. The apparatus consists of a programmable fraction collector (with attachments for preparative work) driven by a high-flow peristaltic pump. To reduce bacterial growth and lipid oxidation of the liquid diet, we kept the milk-replacer in an ice bath and bubbled a slow stream of nitrogen through it at all times. The liquid diet was kept in suspension by continuous recirculation and agitation. The device can be used to dispense prespecified amounts of either the same volume of feed, or a different volume to each of two groups of animals at regular intervals over 24 h; alternatively, by using the time-windows feature of the fraction collector, up to 11 different volumes can be dispensed to 11 animals. We present results of a preliminary trial in which we used the equipment to feed 11 pigs, weaned at 1 d of age, for 11 d. Daily maintenance and programming of two systems, including diet preparation and pig weight measurements, were accomplished in approximately 90 min. The feeder is simple to program and enables the feed intake of the pigs to be adjusted accurately for individual BW on a daily basis. The pigs had no diarrhea and grew well on the rations allocated to them.

Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation

Differences in body composition have often been examined in conjunction with measurements of energy expenditure in men and women. Numerous studies during the past decade examined the relationship between resting energy expenditure (REE) and the components of a two-compartment model of composition, namely the fat-free mass (FFM) and the fat mass (FM). A synthetic review of these studies confirms a primary correlation between REE and FFM in adults over a broad range of body weights. A generalized prediction equation is proposed as REE = 370 +/- 21.6 x FFM. This equation explains 65-90% of the variation in REE. Several studies suggest, further, that FFM predicts total daily energy expenditure (TDEE) equally well. An independent contribution by FM to the prediction of either REE or TDEE is not supported for the general population, perhaps reflecting the relative constancy of the absolute FM in nonobese individuals. In the subset of obese women, FM may be a significant predictor.

Reduced mononuclear leukocyte ascorbic acid content in adults with insulin-dependent diabetes mellitus consuming adequate dietary vitamin C

Several recent studies suggest that vitamin C (ascorbic acid [AA]) status may be altered in insulin-dependent diabetes mellitus (IDDM). We measured the AA content of mononuclear leukocytes (MN-AA) as an indicator of tissue vitamin C status in adults with IDDM and nondiabetic adults matched for age and sex. Dietary vitamin C intake and plasma AA were analyzed to ensure that vitamin C availability was adequate. Dietary vitamin C intakes were above recommendations and were not different between the groups. MN-AA was reduced by 33% on average (P less than .05) in adults with IDDM (1.75 microgram/mg total protein [TP]) when compared with nondiabetics (2.60 micrograms/mg TP). When MN-AA is indexed to the dietary vitamin C intake (MN-AA/100 mg diet C), the storage deficit in adults with IDDM averages 50% (P less than .05). This observation suggests an impaired tissue AA storage in adults with IDDM and supports the theory that intracellular scurvy contributes to the chronic degenerative complications of the disease.

Zinc and copper status of severely burned children during TPN

Alterations in zinc (Zn) and copper (Cu) homeostasis have been reported during the acute recovery period following thermal injury in both children and adults. Increased urinary losses of Zn and Cu and decreased plasma concentrations of Zn, Cu, and ceruloplasmin (CP), the major copper transport protein, occur despite adequate provision of these elements in enteral feedings. We now report data for moderately to severely burned children receiving total parenteral nutrition (TPN) supplemented to provide Zn and Cu. Hyperzincuria occurred consistently when 50 micrograms/kg Zn was delivered daily to older children. Similarly, when younger children received 100 micrograms/kg Zn daily, profound hyperzincuria ensued despite a reduction in total plasma Zn. Hypozincemia was accompanied by low levels of Zn in the plasma subfraction normally associated with albumin-bound Zn. The delivery of Cu via TPN was 4-12 micrograms/kg daily, and urinary Cu losses were not elevated. Plasma total Cu and plasma CP were invariably reduced. These findings are discussed in relation to guidelines published for pediatric trace element supplementation during TPN.

Factors contributing to increased energy expenditure in thermal injury: a review of studies employing indirect calorimetry

In summary, a remarkably close agreement exists for the mean MEE measured in 28 studies of severe burn trauma. This is especially surprising given the variability in sample sizes, measurement techniques, study designs, and DPBs studied. The mean MEE calculated from the data published in these reports is listed in the final column of Table I. For more than 450 cases, an unweighted MEE is 2750 +/- 85 kcal/day. For those studies prior to 1980, the mean MEE exceeds 3000 kcal/day in eight of 14 reports vs only two of 14 published after 1980. Even so, the mean MEE for the pre-1980 reports differs by only 200 kcal/day (2960 +/- 120, n = 14). The accepted notion that the degree of elevation in MEE is in proportion to the % BSAB up to about 60% BSAB is useful in a general sense but must be applied with caution. The recent studies, which include proportionately more burns exceeding 80% BSAB, suggest an elevation in MEE in these cases. Nevertheless, a physiologic plateau apparently exists at or slightly below 2 x normal RMR at the peak of MEE. The magnitude of the MEE response results from an undefined interaction among several factors of which some have been examined while others such as inflammatory mediators are only beginning to receive study. The contributions to reduction in MEE from interventions to control cardiac output and peripheral cooling, core temperature, evaporative water (heat) loss, and substrate cycling have been reviewed. The importance of indirect calorimetry in patient care is highlighted by the large variability in similarly injured individuals and in the unexplained component of regression analyses.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholangiocarcinoma occurring after childhood radiotherapy for Wilm's tumor

Some patients have been given radioactive thorium dioxide as an intravascular contrast agent. Retained particles of thorium in the liver have chronically irradiated hepatic tissues and sometimes caused cholangiocarcinomas and other malignancies. We studied a young woman who developed cholangiocarcinoma in liver tissue which was included in the field of external beam therapy given for Wilm's tumor some twenty years earlier. Radiation-induced cholangiocarcinoma may not necessarily require chronic exposure to ionizing radiation.

Cystic thyroid nodules. The dilemma of malignant lesions

A retrospective study of 221 surgically resected thyroid nodules disclosed that 71 (32%) were cystic and 150 (68%) were solid lesions. Ultrasonography correctly characterized cystic nodules in all but one case. Comparing cystic and solid nodules, there were no differences in patient demographics (mean ages, 47.7 +/- 1.8 SEM vs 45.9 +/- 1.2 years; sex, 78% females both groups), the proportion that were solitary (39% vs 40%), or the nodule size (49% vs 47% greater than or equal to 2 cm in diameter). Of cystic thyroid lesions, 4% were simple cysts, 82% were degenerating benign adenomas or colloid nodules, and 14% were malignant compared with 23% of solid lesions that were malignant. Most cystic lesions (81%) contained bloody fluid. One benign true cyst was filled with thick brown fluid, while clear yellow fluid was repeatedly aspirated from one malignant cystic nodule. Malignant fine-needle aspiration cytology was the best predictor of cancer (100%). Much less predictable were signs of local compression or invasion (43%), a history of head or neck irradiation (33%), cyst recurrence after aspiration (29%), or an increase in the cystic nodule's size (7%). Indeterminate cytology identified malignancy with about half the frequency in cystic lesions as compared with solid nodules (13% vs 27%). The only false-negative fine-needle aspiration cytology occurred in a cystic lesion. In patients with cystic papillary cancers, needle aspirates contained insufficient material for diagnosis in 20% that occurred in no patient with solid papillary carcinoma. The sensitivities and specificities of fine-needle aspiration cytology for solid nodules were 100% and 55%, and for cystic nodules were 88% and 52%. Thus, cystic lesions are as likely as solid thyroid lesions to harbor a malignancy that cannot be predicted from the cyst's clinical characteristics or the patient's demographic data. Although fine-needle biopsy is the best predictor of malignancy in either cystic or solid thyroid lesions, it is slightly less reliable when a thyroid lesion is fluid filled rather than solid. We believe that most cysts not abolished by aspiration should be surgically excised.

Sonographic "white line sign" for detection of minimal mucosal thickening in renal transplants

It is important to detect minimal hydronephrosis in a renal transplant because early or low-grade obstruction is clinically significant. Similarly, it is equally important to detect minimal mucosal thickening of the collecting system because this finding indicates the presence of renal disease even though thickening itself is nonspecific as to etiology. Differentiating between minimal hydronephrosis and minimal mucosal thickening may be difficult. We have noticed that meticulous sonograms made with an ultrasound transducer placed perpendicular to the interface of two opposing surfaces of thickened mucosa will produce a bright linear echo which can help discover and distinguish between these two entities. We choose to call this echo complex the "white line sign."

Calorie and protein provision for recovery from severe burns in infants and young children

Severely burned adults increase their metabolic energy expenditure (MEE) to levels approaching twice the normal resting metabolic rate (RMR). There are no available measurements of MEE for severely burned infants and toddlers, however, and nutritional support relies on published estimates of MEE that range from 200% to 400% of RMR. We determined the actual calories provided to 10 infants and children ages 3-33 mo during acute care for severe burns (59 +/- 5% total-body-surface burn). Our standard protocol emphasizes the delivery of amino acids at 3 g.kg-1.d-1 in conjunction with prompt excision and grafting. An anabolic state characterized by weight maintenance and healing was supported with far fewer calories than predicted by four published formulas for MEE. We conclude that when greater than 2.5 g.kg-1.d-1 protein is provided, efficient protein utilization for recovery is achieved with calorie provision at 120-200% RMR in severely burned infants and toddlers.

Unusual lesions imaged with scrotal sonography. Pictorial essay

This pictorial essay consists of 12 cases of unusual disease or an uncommon presentation of a common disorder imaged with scrotal sonography.

Measured and predicted calorie requirements of adults during recovery from severe burn trauma

Major burn trauma produces large elevations in metabolic energy expenditure (MEE) during acute care. However, overfeeding can occur and is detrimental to recovery. The formulae often used to estimate caloric support to meet MEE are based on body weight, predicted resting metabolic rate (RMR), body surface area, or the total body surface area burned (BSAB). These predictive equations originate from studies of less than or equal to 30 patients generally lacking measurements beyond the third week of convalescence. We report 565 measurements by indirect calorimetry for 122 adults between the burn day and day 149 postburn. A standardized protocol of nutritional support and early wound closure was followed. Predictions of MEE are compared in subcategories of BSAB (2-25%; 30-50%; 51-75%; and 76-98%). For major burns exceeding 30% BSAB, 2X the predicted RMR was consistently closest to the measured MEE, assuring adequate calorie provision while minimizing the risk of overfeeding.

Chronic intracerebroventricular CRF infusion attenuates ACTH-corticosterone release

Bolus intracerebroventricular delivery of corticotropin-releasing factor (CRF) elicits acute responses of both the pituitary-adrenal axis and the sympathetic nervous system. We examined whether these stresslike responses could be maintained over a period of days by central delivery of CRF in nonstressed rats, as would be predicted if this peptide participates in the central nervous system regulation of chronic stress. CRF (4.3 or 21.5 micrograms/day) was continuously delivered into the cerebral ventricle via Alzet minipumps. In contrast to saline-infused controls, rats receiving CRF exhibited elevated excretions of corticosterone, norepinephrine, and urea nitrogen for several days. Thereafter, an attenuation of CRF responsiveness occurred when corticosterone excretion returned to basal levels despite continued central CRF infusion. However, CRF delivered intravenously during attenuation stimulated adrenocorticotropic hormone and corticosterone secretion, implicating a hypothalamic rather than pituitary locus for central CRF resistance. The present data do not permit a conclusion on whether the attenuation of the CRF response with time is the result of an ultrashort-loop negative-feedback mechanism or CRF receptor desensitization.

Altered vitamin C transport in diabetes mellitus

Tissues sequester vitamin C in concentrations exceeding that present in plasma. The transmembrane transport mechanisms have been shown to be influenced by the concentration of glucose in vitro. On this basis an impairment of tissue vitamin C status may be present in diabetes mellitus. Recent evidence in support of this hypothesis, first proposed by Mann in 1974, is reviewed.

Methotrexate and bone marrow metaphases

The efficacy of a methotrexate (MTX) block/thymidine release synchronization technique has been assessed in bone marrow cultures from patients with acute nonlymphocytic leukemia and myelodysplasia. In contrast to cultures of stimulated lymphocytes from normal individuals, no improvement in mitotic index (MI) or metaphase quality could be detected using this technique. Demonstration of an unchanged level of division in bone marrow cultures in the presence of MTX suggests that the technique is unsuitable for synchronization purposes in this tissue. The influence of preincubation prior to MTX exposure and duration of exposure to colcemid on MI and metaphase quality have also been examined.

Hypomagnesemia: a multifactorial complication of treatment of patients with severe burn trauma

Hypomagnesemia is reportedly a common complication of care during the early period of recovery from major trauma. Aminoglycoside treatment, by provoking inappropriate renal magnesium wasting, may contribute to the frequency of hypomagnesemia. We examined the magnesium (Mg) status of six severely burned adolescents during the early phase of recovery. Although provision of Mg met recommended levels, hypomagnesemia occurred in every patient. Two of five of our patients were hypomagnesemic during gentamycin treatment, and five of five during subsequent tobramycin therapy (including the three not affected by gentamycin). Additional episodes occurred in five patients in the absence of aminoglycosides. An interrelationship between Mg status and efficacy of potassium repletion is detailed for one patient. Hypomagnesemia during tobramycin treatment was associated with refractoriness to potassium repletion. Recurrence of hypokalemia during a subsequent diuresis-induced hypomagnesemia was prevented by Mg supplementation. The Mg requirement is increased during recovery from severe burns and appears to exceed that provided by commercially available enteral formulations.

Closed-circuit metabolic system with multiple applications

A closed-circuit metabolic system has been designed and tested for multiple applications. Air pressure within a closed chamber is regulated electronically while allowing for respiratory gas exchange. Compared with a previously reported standard indirect calorimetry system, the new device had by virtue of longer duration of measurement improved precision (coefficient of variation 3% vs. 14%) during studies of O2 consumption both at room temperature and at 5 degrees C. In addition, a more physiological atmospheric environment is maintained. This system has also been utilized for simultaneously labeling groups of up to 20 weanling rats with 18O2 over a 2-day period and for exposure of rats to a hyperoxic (84% O2), normobaric environment for 4-day periods. Potential applications include maintenance of pressure (hypobaric through hyperbaric) and O2 (hypoxic through hyperoxic) controlled environments, exposure to toxic gases, study of diurnal variations in metabolic rate, measurement of metabolic expenditure with activity, and adaptation to other species including humans.

In vivo total body electrical conductivity following perturbations of body fluid compartments in rats

Total body electrical conductivity (TOBEC) provides a rapid and safe noninvasive technique for the assessment of total body water in animals and man. An instrument employing this principle has been shown to measure body water in healthy Sprague-Dawley rats. With the exception of adult obesity in humans, alterations in body fluid compartments that could theoretically affect the utility of conductivity measurements have not been studied. We, therefore, applied the total body electrical conductivity measurement in rats following perturbations of body fluid/electrolyte spaces including obesity, furosemide diuresis, severe burn, and low protein diet. Our findings confirm that total body water can be accurately measured by TOBEC in conditions of abnormal body fluid distribution. However, when the ratio of intracellular to extracellular fluid is significantly reduced, such as the severe burn or low protein intake, TOBEC does not reflect the intracellular (potassium) space but does predict total water and extracellular (sodium) space.

Hypercorticosteronuria and diminished pituitary responsiveness to corticotropin-releasing factor in obese Zucker rats

Metabolic defects in obese (fa/fa) Zucker rats have previously been shown to be reversed by adrenalectomy; however, hypercorticosteronemia has not been demonstrated. We now report that the total daily excretion of corticosterone and urea nitrogen are significantly greater (P less than 0.01) in obese Zucker rats than in age-matched lean Zucker rats. This excessive excretion of corticosterone is not of autonomous adrenal origin, since dexamethasone treatment (20 micrograms/kg X day) for 2 days induced a proportionate reduction in corticosterone excretion (approximately 50%) in both obese and lean Zucker rats. Corticosterone excretion was further suppressed to levels not different from those in lean rats after 2 days of dexamethasone (40 micrograms/kg X day). Both the peak and total pituitary beta-endorphin secretion in response to an iv bolus of corticotropin-releasing factor (CRF) were diminished in obese Zuckers. The response to CRF in obese Zucker rats was dampened and superimposable on that of dexamethasone-treated lean Zucker rats, suggesting the existence of chronic hypercorticosteronemia as a component of this genetic obesity. These observations provide evidence for a compensatory alteration of the pituitary-adrenal axis. We suggest that corticosterone turnover may be increased in obese Zucker rats.

Enhanced hepatic insulin sensitivity and peripheral glucose uptake in cold acclimating rats

Cold-exposed rats exhibit hypermetabolism, hyperphagia, and increased glucose oxidation. Their counterregulatory hormone secretion is markedly elevated, while insulin levels fall acutely, gradually returning to basal during acclimation. We assessed both hepatic and peripheral sensitivity to insulin in rats in the basal state and after 5 days of cold (5 C) exposure. The contribution of gluconeogenesis to total glucose turnover was measured and compared to daily urinary corticosterone excretion. Hepatic glucose production was equally suppressed by the infusion of insulin at 1.2 mU/kg X min in both control and cold-acclimated rats, but enhanced hepatic sensitivity to low dose (0.6 mU/kg X min) insulin infusion was only observed after cold exposure. The metabolic clearance of glucose was elevated with cold stress and was insensitive to the infusion of insulin at either level. Insulin resistance was not observed. Urinary excretion of corticosterone and urea nitrogen were markedly increased, but creatinine excretion was unchanged, suggesting that the concurrent increase in gluconeogenesis resulted from increased protein intake rather than increased catabolism of muscle protein.

The analysis of glucose kinetics using a single jugular catheter in awake rats

The rates of glucose production and utilization can be estimated by a primed-constant infusion technique using separate catheters for the infusion of radiolabelled glucose and periodic blood withdrawal. In rats, a carotid artery catheter is most often combined with a jugular or femoral venous catheter in such studies. We presently describe a method which utilizes a single jugular catheter for both infusion and sampling in the awake rat. This method is directly compared with simultaneous carotid artery sampling during both the dynamic steady state and a nonsteady state induced by a constant infusion of insulin. Our results demonstrate the validity of a single vein design for the analysis of glucose kinetics in either state. Rapid sampling and complete flushing prevent disruption of infusate equilibrium and sample contamination respectively. This single catheter method requires less technical skill for placement, reduces surgical intervention and enhances the comfort of the awake rat.

Sonographic measurement of the extrahepatic bile duct before and after retrograde cholangiography

The maximum diameter of the extrahepatic bile duct visible on cholesonograms was measured immediately before and immediately after endoscopic retrograde cannulation and injection of the biliary and pancreatic ducts (ERCP) in 24 patients. Sonographic bile duct diameter increased by 3 mm or more in nine patients, all of whom had had a previous cholecystectomy. Bile duct diameter was unchanged in the remaining 15 patients, six of whom had had cholecystectomy. The technical performance of ERCP alone will alter bile duct diameter in a significant proportion of patients having endoscopic cannulation of the biliary tree. This is particularly so for patients who have had their gallbladders removed. The true diameter of the extrahepatic bile duct cannot be determined in many patients by simple measurement of images obtained at ERCP, even when corrections are made for radiographic magnification.

Reduced-speckle imaging. A simple technique for improving real-time sonograms

Reduced-speckle images can be produced easily and consistently with the use of real-time sonographic equipment and commercially available multiformat imagers. Such images often show anatomic details better than do traditional images.