Concerted Antibody and Antigen Discovery by Differential Whole-cell Phage Display Selections and Multi-omic Target Deconvolution

Monoclonal antibody (mAb)-based biologics are well established treatments of cancer. Antibody discovery campaigns are typically directed at a single target of interest, which inherently limits the possibility of uncovering novel antibody specificities or functionalities. Here, we present a target-unbiased approach for antibody discovery that relies on generating mAbs against native target cell surfaces via phage display. This method combines a previously reported method for improved whole-cell phage display selections with next-generation sequencing analysis to efficiently identify mAbs with the desired target cell reactivity. Applying this method to multiple myeloma cells yielded a panel of >50 mAbs with unique sequences and diverse reactivities. To uncover the identities of the cognate antigens recognized by this panel, representative mAbs from each unique reactivity cluster were used in a multi-omic target deconvolution approach. From this, we identified and validated three cell surface antigens: PTPRG, ICAM1, and CADM1. PTPRG and CADM1 remain largely unstudied in the context of multiple myeloma, which could warrant further investigation into their potential as therapeutic targets. These results highlight the utility of optimized whole-cell phage display selection methods and could motivate further interest in target-unbiased antibody discovery workflows.

A Sortase A Programmable Phage Display Format for Improved Panning of Fab Antibody Libraries

Phage display of combinatorial antibody libraries is a versatile tool in the field of antibody engineering, with diverse applications including monoclonal antibody (mAb) discovery, affinity maturation, and humanization. To improve the selection efficiency of antibody libraries, we developed a new phagemid display system that addresses the complication of bald phage propagation. The phagemid facilitates the biotinylation of fragment of antigen binding (Fab) antibody fragments displayed on phage via Sortase A catalysis and the subsequent enrichment of Fab-displaying phage during selections. In multiple contexts, this selection approach improved the enrichment of target-reactive mAbs by depleting background phage. Panels of cancer cell line-reactive mAbs with high diversity and specificity were isolated from a naïve chimeric rabbit/human Fab library using this approach, highlighting its potential to accelerate antibody engineering efforts and to empower concerted antibody drug and target discovery.

Human Serum Albumin Domain I Fusion Protein for Antibody Conjugation

Bioorthogonal labeling of antibodies enables the conjugation of compounds, such as small molecules or peptides, which expand targeting capacity or enhance cytotoxicity. Taking advantage of a cyclohexene sulfonamide compound that site-selectively labels Lys64 in human serum albumin (HSA), we demonstrate that domain I of HSA can be used as a fusion protein for the preparation of antibody conjugates. Trastuzumab fusions were expressed at the N-terminus of the light chain or the C-terminus of the heavy chain enabling conjugation to small molecules. Moreover, these conjugates retained HER2 binding and proved to be highly stable in human plasma. Antibody conjugation via HSA domain I fusion should therefore have broad utility for making serum-stable antibody conjugates, particularly for antibody-drug conjugates.

Identification of a Binding Site for Unsaturated Fatty Acids in the Orphan Nuclear Receptor Nurr1

Nurr1/NR4A2 is an orphan nuclear receptor, and currently there are no known natural ligands that bind Nurr1. A recent metabolomics study identified unsaturated fatty acids, including arachidonic acid and docosahexaenoic acid (DHA), that interact with the ligand-binding domain (LBD) of a related orphan receptor, Nur77/NR4A1. However, the binding location and whether these ligands bind other NR4A receptors were not defined. Here, we show that unsaturated fatty acids also interact with the Nurr1 LBD, and solution NMR spectroscopy reveals the binding epitope of DHA at its putative ligand-binding pocket. Biochemical assays reveal that DHA-bound Nurr1 interacts with high affinity with a peptide derived from PIASγ, a protein that interacts with Nurr1 in cellular extracts, and DHA also affects cellular Nurr1 transactivation. This work is the first structural report of a natural ligand binding to a canonical NR4A ligand-binding pocket and indicates a natural ligand can bind and affect Nurr1 function.

Deconvolution of Complex 1D NMR Spectra Using Objective Model Selection

Fluorine (¹⁹F) NMR has emerged as a useful tool for characterization of slow dynamics in ¹⁹F-labeled proteins. One-dimensional (1D) ¹⁹F NMR spectra of proteins can be broad, irregular and complex, due to exchange of probe nuclei between distinct electrostatic environments; and therefore cannot be deconvoluted and analyzed in an objective way using currently available software. We have developed a Python-based deconvolution program, decon1d, which uses Bayesian information criteria (BIC) to objectively determine which model (number of peaks) would most likely produce the experimentally obtained data. The method also allows for fitting of intermediate exchange spectra, which is not supported by current software in the absence of a specific kinetic model. In current methods, determination of the deconvolution model best supported by the data is done manually through comparison of residual error values, which can be time consuming and requires model selection by the user. In contrast, the BIC method used by decond1d provides a quantitative method for model comparison that penalizes for model complexity helping to prevent over-fitting of the data and allows identification of the most parsimonious model. The decon1d program is freely available as a downloadable Python script at the project website (https://github.com/hughests/decon1d/).

Inhibition of Non-ATG Translational Events in Cells via Covalent Small Molecules Targeting RNA

One major class of disease-causing RNAs is expanded repeating transcripts. These RNAs cause diseases via multiple mechanisms, including: (i) gain-of-function, in which repeating RNAs bind and sequester proteins involved in RNA biogenesis and (ii) repeat associated non-ATG (RAN) translation, in which repeating transcripts are translated into toxic proteins without use of a canonical, AUG, start codon. Herein, we develop and study chemical probes that bind and react with an expanded r(CGG) repeat (r(CGG)(exp)) present in a 5' untranslated region that causes fragile X-associated tremor/ataxia syndrome (FXTAS). Reactive compounds bind to r(CGG)(exp) in cellulo as shown with Chem-CLIP-Map, an approach to map small molecule binding sites within RNAs in cells. Compounds also potently improve FXTAS-associated pre-mRNA splicing and RAN translational defects, while not affecting translation of the downstream open reading frame. In contrast, oligonucleotides affect both RAN and canonical translation when they bind to r(CGG)(exp), which is mechanistically traced to a decrease in polysome loading. Thus, designer small molecules that react with RNA targets can be used to profile the RNAs to which they bind in cells, including identification of binding sites, and can modulate several aspects of RNA-mediated disease pathology in a manner that may be more beneficial than oligonucleotides.

Tethered particle motion reveals that LacI·DNA loops coexist with a competitor-resistant but apparently unlooped conformation

The lac repressor protein (LacI) efficiently represses transcription of the lac operon in Escherichia coli by binding to two distant operator sites on the bacterial DNA and causing the intervening DNA to form a loop. We employed single-molecule tethered particle motion to observe LacI-mediated loop formation and breakdown in DNA constructs that incorporate optimized operator binding sites and intrinsic curvature favorable to loop formation. Previous bulk competition assays indirectly measured the loop lifetimes in these optimized DNA constructs as being on the order of days; however, we measured these same lifetimes to be on the order of minutes for both looped and unlooped states. In a range of single-molecule DNA competition experiments, we found that the resistance of the LacI-DNA complex to competitive binding is a function of both the operator strength and the interoperator sequence. To explain these findings, we present what we believe to be a new kinetic model of loop formation and DNA competition. In this proposed new model, we hypothesize a new unlooped state in which the unbound DNA-binding domain of the LacI protein interacts nonspecifically with nonoperator DNA adjacent to the operator site at which the second LacI DNA-binding domain is bound.

Comparison of a beta-lactam alone versus beta-lactam and an aminoglycoside for pulmonary exacerbation in cystic fibrosis

We determined whether a beta-lactam and an aminoglycoside have efficacy greater than a beta-lactam alone in the management of a pulmonary exacerbation in patients with cystic fibrosis.

STUDY DESIGN

Azlocillin and placebo or azlocillin and tobramycin were administered to 76 patients with a pulmonary exacerbation caused by Pseudomonas aeruginosa in a randomized double-blind, third-party monitored protocol. Improvement was assessed by standardized clinical evaluation, pulmonary function testing, sputum bacterial density, sputum DNA content, and time to the next pulmonary exacerbation requiring hospitalization.

RESULTS

No significant difference was seen between the 2 treatment groups in clinical evaluation, sputum DNA concentration, forced vital capacity, forced expiratory volume in second 1, or peak expiratory flow rate at the end of treatment (33 receiving azlocillin alone and 43 both antibiotics); adverse reactions were equivalent in each group. Sputum P. aeruginosa density decreased more with combination therapy (P =.034). On follow-up evaluation, an average of 26 days after the end of treatment, all outcome indicators had worsened in both groups. Time to readmission for a new pulmonary exacerbation was significantly longer in the group receiving azlocillin plus tobramycin (P <.001). Treatment-emergent tobramycin resistance occurred in both groups and was more frequent with combination therapy.

CONCLUSION

We conclude that the combination of a beta-lactam and an aminoglycoside produces a longer clinical remission than a beta-lactam alone and slightly better initial improvement.

The Kentucky medical curriculum. A response to the call for educational reform: a GPEP report card

The resources of an important educational grant provided by the Robert Wood Johnson Foundation, as well as designated local college and medical center funds, provided support for the renewal of the undergraduate medical education program at the University of Kentucky College of Medicine. The fully revised medical curriculum, adapted to changing professional and societal needs and completely in place by the 1994-95 academic year, was influenced by the recommendations of the General Professional Education of the Physician (GPEP) Report, issued by the Association of American Medical Colleges in 1984. This paper details each of the student-centered curricular changes in the context of the GPEP recommendation that it particularly addresses.

Physicians for the 21st century: implications for medical practice, undergraduate preparation, and medical education

Changes in medical education and the practice of medicine have resulted from the push for both education and health care reforms. Undergraduates planning application to medical school should broaden their preparation to include communications, computers, economics, and multicultural educational experiences. To prepare graduates for medical practice in the new millennium, the University of Kentucky College of Medicine has implemented a new curriculum focusing on integration of basic and clinical sciences, primary care in ambulatory sites, health promotion and disease prevention, and attention to the ethical, social, psychologic, and financial impact of disease upon the patient, family, and society.

Chloroplast DNA diversity among wild and cultivated members of Cucurbita (Cucurbitaceae)

Cladistic analysis of 86 chloroplast DNA restriction-site mutations among 30 samples representing 15 species of Cucurbita indicates that annual species of the genus are derived from perennials. The Malabar Gourd, C. ficifolia, is placed as a basal, sister taxon relative to other domesticated species and allied wild-types. The pattern of variation supports three species groups as monophyletic: (1) C. fraterna, C. pepo, and C. texana, (2) C. lundelliana, C. martinezii, C. mixta, C. moschata and C. sororia, and (3) C. foetidissima and C. pedatifolia. Domesticated samples representing subspecies of C. pepo are divided into two concordant groups, one of which is allied to wild-types referable to C. texana and C. fraterna. The data failed to resolve relationships among cultivars of C. moschata and C. mixta and their association to the wild C. sororia. The South American domesticate, C. maxima, and its companion weed, C. andreana, show close affinity and alliance to C. equadorensis.

Effects of resection on absorption and secretion of divalent cations by small intestine of rat

Resection increases villus height and crypt depth of remaining intestine. We examined functional consequences of resection by measuring absorption of strontium and secretion of calcium and magnesium by proximal and distal segments remaining after resecting 70% of mid small intestine. Compared with the transected control group, resection decreased strontium absorption per unit weight of mucosa (specific absorption) in the proximal segment. The decreased specific absorption was compensated by increased mucosal growth in the resected group so that absorption per unit length of segment (per cm) was the same in both groups. Resection increased secretion of calcium and magnesium by 66% per unit weight of mucosa and by 145%/cm in the distal segment. Comparing proximal with distal segments in the resected group, secretion was greater in distal for calcium and in proximal for magnesium. Intestinal resection causes responses in absorption and secretion of divalent cations important in mineral homeostasis.

Effects of phospholipid or cholesterol enrichment of rat intestinal brush border membrane on membrane order and transport of calcium

Calcium uptake by brush border membrane vesicles from rat small intestine measured under initial rate conditions comprises both saturable and nonsaturable components. Because the brush border is a lipid bilayer and may be sensitive to changes in membrane lipid, vesicles were treated with liposomes to enrich phospholipid (PL) or cholesterol (C) content above that of the control (Reference) vesicle. The effects of the changes in lipid composition on membrane fluidity were determined from fluorescence anisotropy (r) of diphenylhexatriene. Compared with Reference vesicles, liposome-treated vesicles showed decreased Vmax for saturable and KD for nonsaturable uptakes. Liposome treatment changed vesicle phospholipid composition compared with Reference vesicles. Liposome-treated vesicles had similar phospholipid composition but differed in greater cholesterol content of C- compared with PL-vesicles. Mean Vmax and KD were lower in C- than PL-vesicles, but the difference did not reach statistical significance, although fluidity was significantly lower in C- than PL-vesicles. The mechanism of inhibition of saturable calcium uptake in PL- and C-vesicles was uncompetitive. Thus, lipid composition is crucial for determining calcium uptake: any change from native lipid composition decreased transport. Fluidity, measured by the conventional probe diphenylhexatriene, did not correlate with calcium uptake by Reference compared with liposome-treated vesicles.

Calcium uptake by brush-border membrane vesicles from the rat intestine

Uptake of calcium by brush-border membrane vesicles from rat small intestine is composed of saturable and nonsaturable components. We studied regulation of calcium uptake using the divalent cations strontium, a foreign ion that mimics calcium biologically and magnesium, a physiologically important ion that resembles calcium physically, although not biologically. Strontium present outside the vesicle inhibited saturable calcium uptake competitively, consistent with binding to the transporter at the same site as calcium. Strontium inside the vesicle accelerated saturable calcium uptake from the outside (countertransport), also consistent with binding to the same transporter site as calcium. Thus the calcium transporter shows functional characteristics of a mobile carrier. In the uptake medium (extracellular), magnesium was a noncompetitive inhibitor of saturable calcium transport, consistent with a regulatory role in calcium uptake by binding to the transporter at a locus other than that for calcium. Magnesium at 1 mM concentration inside the vesicle had no effect on saturable calcium uptake and a high concentrations functioned as a week uncompetitive inhibitor. Thus intracellular magnesium appears to have no major role in regulating saturable calcium uptake at the brush border of the enterocyte.

Calcium transport in the spontaneously hypertensive rat is responsive to vitamin D

Intestinal calcium transport rate and response to treatment with a vitamin D agonist [24,24-difluoro-1,25-dihydroxycholecalciferol, F2-1,25-(OH)2D3)] were studied in the spontaneously hypertensive (SH) rat-Wistar Kyoto (WKy) rat model of hypertension. We used the everted duodenal sac to study untreated, orally treated, and parenterally treated groups of SH and WKy rats. In untreated groups, net calcium transport was lower (P less than 0.05) in the SH rat than in the WKy rat (0.46-0.66 vs 0.81-1.04, all data mumole/g segment wet wt per hr). Both groups responded to treatment (SH vs WKy; 0.84-0.90 vs 1.56-1.57, P less than 0.05), but even in treated groups net calcium transport by the SH rat was lower than that by the WKy rat (P less than 0.05). Net water transport increased 3- to 8-fold in response to treatment in the WKy but not in the SH rat. The increased water transport prevented demonstration of treatment-mediated increased calcium transport based on serosal/mucosal concentration ratio in the WKy rat. We conclude that (i) both the SH and the WKy rat have the capability to increase calcium transport when treated with an agonist having vitamin D activity; (ii) the unstimulated and stimulated transport rate is lower in the SH rat than in the WKy rat; and (iii) water transport responds to treatment in the WKy rat but not in the SH rat.

Calcium transport and vitamin D in three breeds of spontaneously hypertensive rats

Conflicting results have been published by different laboratories comparing the rate of intestinal calcium transport and concentration of circulating 1,25-dihydroxyvitamin D (1,25-[OH]2D) in the spontaneously hypertensive rat (SHR) and control Wistar-Kyoto rat (WKY): They have been reported to be greater, the same, or lower in the SHR than in the WKY. We tested the possibility that the conflicting results might be breeder-related by measuring 1) the rate of intestinal mucosal calcium transport, 2) the concentration of circulating 25-hydroxyvitamin D (25-OH-D) and 1,25-(OH)2D, and 3) the concentration of intestinal mucosal receptor for 1,25-(OH)2D in the two strains of animals from three different breeders. Sodium and water transport were also measured because of their relevance to hypertension. Blood pressure was always higher and calcium, as well as mean sodium and water transport, was always lower in the SHR than in the WKY. The concentration of 1,25-(OH)2D was the same, higher, or lower in the SHR than in the WKY and was age- and breeder-dependent. Mean mucosal 1,25-(OH)2D receptor concentration was higher in the SHR and was variable, depending on breeder. We conclude that 1) the rate of calcium transport is lower in the SHR than in the WKY and independent of breeder and concentration of 1,25-(OH)2D in serum, 2) the variability in 1,25-(OH)2D concentration among investigators may be breeder-dependent, and 3) the higher receptor concentration in the intestinal mucosa of the SHR could be a compensatory response to the decreased rate of calcium transport. These differences in calcium and sodium transport may be an expression in the enterocyte of factors etiological for hypertension.

Morphological and functional recovery of rat small intestine following localized hyperthermia

Structural and functional changes in the rat small intestine following localized hyperthermia were examined. In anaesthetized male Sprague-Dawley rats a 10 cm segment of mid-small intestine was temporarily exteriorized, suspended in a cup containing Krebs-Ringer solution, and either heated at 43.5 degrees C or sham-heated at 38 degrees C for 45 min. The intestinal segments were studied 1, 4, 7, 21 and 42 days later by histopathological examination, determination of wet weight, dry weight and gross segment area, and by measuring absorption of 15 mM D(+)-glucose containing 14C-labelled D(+)-glucose as a tracer. Intestinal glucose transport was assessed by two different techniques: the everted sac method (in vitro) and luminal perfusion-recirculation (in vivo). After 1 day, heated intestinal segments exhibited marked mucosal damage, consisting of loss of epithelial cells and destruction of villi. Re-epithelialization had occurred by day 4, but mucosal architecture remained abnormal throughout the observation period. Hyperthermia caused significant thickening of the intestinal wall: at 4 days the thickening was due to oedema, whereas at 42 days tissue mass per cm2 in heated segments had increased by approximately 53 per cent compared with sham-heated control segments. At 1 day, net glucose transport in vitro in heated segments was reduced to 20 per cent and the serosal/mucosal concentration ratio to 57 per cent of that of control segments. In vivo, glucose transport in heated intestine at 4 days was 45 per cent of that of controls. From 4 days on, glucose transport improved gradually, and at 42 days there was no significant difference between heated and sham-heated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium and sodium transport in the duodenum of the Dahl salt sensitive and salt resistant rat

We measured food intake, body growth and transport of calcium and sodium by duodenum of female Dahl salt sensitive (DS) and salt resistant (DR) rat strains. Food intake and body growth were similar for DS and DR rats taking both 0.4 and 8% sodium chloride diets. Food intake increased with age up to 5 weeks and then remained constant despite continuing body growth. Comparing DS and DR rats fed the 0.4% sodium chloride diet at 6 and 11 weeks or the 8% sodium chloride diet at 6 weeks, transport of calcium and sodium were the same in both the DS and DR groups. Transport of calcium, but not sodium, was lower at 11 than at 6 weeks. Comparing simultaneous feeding of either 0.4 or 8% sodium chloride diets to 6-week old DS and DR rat strains, transport of calcium tended to be lower in animals fed the 8% as compared to the 0.4% sodium chloride diet, and the difference was significant for net 40Ca transport for DR rats. The DS rat fed on 8% sodium chloride had higher systolic blood pressure (SBP) than the DR rat. We conclude that growing DS and DR rats, ingesting equal amounts of food, do not differ in duodenal calcium and sodium transport measured by the everted sac technique. The response to feeding sodium chloride differs between strains: the high salt diet decreases net 40Ca transport in the DR but not the DS strain.

Increased intestinal growth in the streptozotocin-diabetic rat occurs prior to changes in hormone secretion

Depressed somatic growth in the rat with streptozotocin diabetes is associated with greatly enhanced intestinal growth. In patients with diabetes mellitus, growth hormone is elevated. Therefore, we measured the association between gut growth and serum growth hormone in the streptozotocin-diabetic rat. At 10 days growth hormone did not differ in control, untreated diabetic and insulin-treated diabetic groups. At 20 days of diabetes, growth hormone was elevated in untreated diabetic groups, but depressed to control levels by insulin. Intestinal growth was markedly elevated in all diabetic groups by 10 days, prior to the increases in hormone levels. We conclude that the enhanced intestinal growth in diabetes is probably independent of growth hormone.

Gastrin, somatostatin, and alimentary tract growth responses to small intestinal resection in the rat

We studied the early time-course of gastrin, somatostatin, and gut growth responses to 70% resection of mid-small intestine. Serum and antral gastrin increased by the 2nd day following resection and remained elevated for the 10-day period of study. Antral somatostatin remained unchanged, suggesting that the increase in gastrin was a selective antral response. Duodenum and ileum showed marked growth stimulation, which was progressive with time, and earlier and greater in duodenum. In contrast, gastric growth was unaffected. Thus, early responses to resection are characterized by specificity of gastrin, somatostatin, and growth effects.

Intestinal disaccharidase activity following pancreatic duct occlusion in the rat

The influence of pancreatic secretions on growth and brush-border enzyme activity, throughout the entire small intestine, was examined in the rat. Pancreatic secretions were excluded from the gut lumen by stapling the pancreatic ducts, without interruption of bile flow. The entire small intestine was studied as four segments; the duodenum and three distal segments of equal length. Weight of intestine and mucosa, and mucosal sucrase, isomaltase, lactase, and alkaline phosphatase activity were measured 10-15 days following pancreatic duct occlusion, or sham-operation. The duodenum of pancreatic duct-occluded animals exhibited significant hypertrophy. In general, specific and total disaccharidase activities were greater in duct-occluded animals than in controls throughout the intestine. The increase was more pronounced in distal than in proximal segments. The sucrase/isomaltase ratio was significantly greater in pancreatic duct-occluded animals than in controls in the two distal segments. Alkaline phosphatase activity was not affected by pancreatic duct occlusion. The greater relative increase of disaccharidase activities and sucrase/isomaltase activity ratios in the distal segments of duct-occluded animals, indicates a more important regulatory role of pancreatic enzymes in the distal small intestine. It is concluded that regulation of intestinal brush-border enzyme activity by pancreatic secretion is selective for enzyme and site as follows: disaccharidases, but not alkaline phosphatase, are regulated; the sucrase subunit of the sucrase/isomaltase complex is most sensitive to regulation, while lactase is least sensitive; and the regulatory effect on disaccharidases is greater in distal than in proximal intestine.

Resection of rat small intestine: calcium, phosphorus, and fat balances and 1,25-dihydroxycholecalciferol

In rat with massive resection of mid-small intestine, calcium transport per segment, measured by in vivo perfusion 10 days after surgery, is decreased in duodenum and ileum but is the same in cecum and colon as compared with controls with transection and reanastomosis of mid-small intestine. To extend these findings, we measured balances of calcium, phosphorus, and fat from the 5th to 10th day after surgery and serum concentration of 1,25-dihydroxycholecalciferol on the 10th day after surgery in this experimental model. We found steatorrhea in the resected group, but balances of calcium and phosphorus and serum levels of 1,25-dihydroxycholecalciferol were the same in resected and control groups. We conclude that decreased transport defined by direct examination of membrane function may be undetectable when net transport is measured by balance. Calcium balance during early post-resection period provides no evidence for future calcium deficiency in this experimental model.

Intestinal calcium transport in the spontaneously hypertensive rat: response to calcium depletion

We previously found intestinal Ca2+ transport to be lower in the spontaneously hypertensive (SH) as compared with the Wistar-Kyoto control (WKY) rat. These animals were fed a relatively high (1%) Ca2+ diet, and the concentration of 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3] in serum was the same in both groups. In the present experiment we tested the possibility that the lower Ca2+ transport in the SH rat was the result of unresponsiveness to 1 alpha,25(OH)2D3. We fed diets high and low in Ca2+ and measured serum 1 alpha,25(OH)2D3 and Ca2+ transport. Serum 1 alpha,25(OH)2D3 increased in response to Ca2+ depletion at both 5 and 12 wk in both the WKY and SH rat. With high-Ca2+ diet, Ca2+ transport was lower in SH than in WKY when studied 1) in vitro in duodenum at 5 wk of age, and 2) in vivo in proximal and distal small intestine at 12 wk of age. Ca2+ transport increased in SH in response to Ca2+ depletion, but not in WKY, except in distal small intestine in vivo at 12 wk. In summary, although Ca2+ transport is lower in the SH as compared with the WKY rat when vitamin D activity is basal through feeding a high-Ca2+ diet, Ca2+ transport increases in the SH rat in response to the increase in 1 alpha,25(OH)2D3 produced by feeding a low-Ca2+ diet. We conclude that 1) the vitamin D-regulated component of mediated Ca2+ transport is intact in the SH rat and is unrelated to hypertension, and 2) mediated Ca2+ transport under basal conditions, i.e., nonvitamin D-regulated, differs in the SH and WKY rats and may be related to hypertension.

Measurement of alpha-glucosidase activity in serum from patients with cystic fibrosis or pancreatitis

We measured the activity of a non-lysosomal alpha-glucosidase with pH optimum near 6.0 in serum from a wide variety of patients, using the fluorogenic substrate, 4-methylumbelliferyl-alpha-D-glucopyranoside. Acutely ill patients with cystic fibrosis (CF) demonstrated significant increases in alpha-glucosidase compared with CF outpatients. The former group of CF patients experienced far more severe chronic pulmonary disease than did the latter, whereas both groups had similar degrees of gastrointestinal impairment. Patients with pancreatitis associated with trauma or complicated by severe necrosis, hemorrhage, or abscess also displayed greater increases in alpha-glucosidase than did patients with uncomplicated (edematous) pancreatitis. For CF outpatients and patients with either edematous pancreatitis or pancreatic cancer, the alpha-glucosidase activity was similar to that for the general hospital-patient population. Corresponding changes were not observed for other measured serum glycosidases (alpha-fucosidase, alpha-mannosidase, beta-glucuronidase, beta-N-acetylglucosaminidase). Measurement of serum alpha-glucosidase may be of value in assessing the clinical course in CF and in differentiating necrotizing from edematous pancreatitis.

Measurement of alpha-glucosidase activity in serum from patients with cystic fibrosis or pancreatitis

We measured the activity of a non-lysosomal alpha-glucosidase with pH optimum near 6.0 in serum from a wide variety of patients, using the fluorogenic substrate, 4-methylumbelliferyl-alpha-D-glucopyranoside. Acutely ill patients with cystic fibrosis (CF) demonstrated significant increases in alpha-glucosidase compared with CF outpatients. The former group of CF patients experienced far more severe chronic pulmonary disease than did the latter, whereas both groups had similar degrees of gastrointestinal impairment. Patients with pancreatitis associated with trauma or complicated by severe necrosis, hemorrhage, or abscess also displayed greater increases in alpha-glucosidase than did patients with uncomplicated (edematous) pancreatitis. For CF outpatients and patients with either edematous pancreatitis or pancreatic cancer, the alpha-glucosidase activity was similar to that for the general hospital-patient population. Corresponding changes were not observed for other measured serum glycosidases (alpha-fucosidase, alpha-mannosidase, beta-glucuronidase, beta-N-acetylglucosaminidase). Measurement of serum alpha-glucosidase may be of value in assessing the clinical course in CF and in differentiating necrotizing from edematous pancreatitis.

Adaptation of the duodenum and ileum of the rat to mid-gut resection: enzyme activity and trace metal status

Activities of the enzymes lactase, sucrase, maltase, alkaline phosphatase, and superoxide dismutase (SOD) were measured in mucosa of duodenum and ileum of the rat after 70% resection of mid-small intestine or sham operation (transection). We also measured the concentrations of zinc, copper, and manganese in several tissues to assess trace metal homeostasis postresection. Resection resulted in decreased specific activities of disaccharidases and alkaline phosphatase in duodenum, while specific activities remained unchanged in ileum. Specific activity of total SOD (the sum of Cu-Zn and Mn SOD) and Mn SOD was the same in duodenum after resection but was markedly increased in ileum. Tissue trace metal concentrations changed minimally. Because of postresection mucosal growth, total segmental activity of disaccharidases and alkaline phosphatase was the same in duodenum and increased in ileum of resected compared to transected rats. Segmental activity of total SOD and Mn SOD doubled in duodenum and trebled in ileum of resected as compared to transected rats. Thus, total segmental enzyme activity is maintained or increased postresection by increased enterocyte proliferation rate and mucosal growth.

Calcium uptake by intestinal brush border membrane vesicles. Comparison with in vivo calcium transport

In prior studies, we examined kinetics of steady state in vivo transepithelial calcium transport in rat and hamster. The present studies related calcium uptake by the brush border to in vivo transport. We measured calcium uptake by brush border membrane vesicles from the two species. In the rat, our prior in vivo studies had shown that (a) calcium transport was mediated, (b) no nonmediated component was detectable, and (c) Vmax was 2.5 times greater in proximal than distal small intestine. In brush border membrane vesicles from the rat, Vmax for the saturable component of calcium uptake was again 2.5 times greater in proximal than distal intestine. Contrasting with in vivo studies, a major nonsaturable component was present in vesicles from proximal and distal small intestine. In the hamster, our previous in vivo studies had shown (1) both mediated and nonmediated components of calcium transport, (2) greater nonmediated transport in proximal than distal small intestines, and (3) Vmax for calcium transport twice as great in distal as in proximal small intestine. In the present study with brush border membrane vesicles from hamster, Vmax for saturable calcium transport was again twice as great in distal as in proximal small intestine. However, nonsaturable calcium transport rates relative to saturable rates were much greater with vesicles than in in vivo studies, and were greater in vesicles from distal than proximal small intestine. Since rates of saturable calcium uptake by brush border membrane vesicles parallel corresponding in vivo mediated transport rates, we conclude that the segmental rates of calcium transport in rat and hamster could be determined by brush border function.

Brain biopsy in cases of neonatal herpes simplex encephalitis

Neonatal herpes simplex encephalitis (HSE) can represent a difficult diagnostic problem when it occurs without concomitant mucocutaneus lesions and usually requires brain biopsy for diagnosis. Asymptomatic for the initial 2 to 4 weeks of life, the three infants we describe with localized HSE came to medical attention only because they developed persistent seizures and other nonspecific symptoms. Lumbar spinal fluid obtained from these children at clinical presentation showed an encephalitic pattern. Radionuclide brain scans revealed focal uptake of isotope in a variety of cortical areas, and electroencephalograms (EEGs) demonstrated repetitive, high amplitude, polyphasic sharp waves arising from analogous regions. Computed tomography (CT) showed nonspecific ill-defined areas of low density or contrast enhancement that did not correlate well with radionuclide, EEG, or clinical findings in two neonates. No infant had predominant temporal lobe involvement. Because these data suggested a multifocal, encephalitic process, all three infants underwent brain biopsy. A widespread infiltration of leukocytes and macrophages was observed in each specimen, and abundant intranuclear inclusions were present. Electron microscopy revealed abundant herpesvirus particles, and herpes simplex virus (HSV) was subsequently isolated from each sample. From our observations and our review of the literature, we propose the following criteria as indications for brain biopsy: Brain biopsy is warranted to rule out HSE when a neonate presents with seizures, cerebrospinal fluid mononuclear pleocytosis with a negative gram stain, and focal, cortical disease on EEG and radionuclide scan.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatal panniculitis

The Weber-Christian syndrome (relapsing nodular panniculitis) displays a clinical spectrum varying from short, self-limited, or intermittent disease episodes to persistent disease with fatal outcome. Inflamed adipose tissue is exclusively subcutaneous in some patients and is both subcutaneous and perivisceral in others. Inflammation of fat may induce a focal cutaneous or a systemic extracutaneous histiocytic proliferative response in which hemophagocytosis may be a frequent characteristic. Major causes of death--sepsis, hepatic failure, hemorrhage, and thrombosis--are identical in the patients with and without the systemic histiocytic proliferation. Inflammation in fat, of and by itself, may be associated with significant morbidity and mortality, regardless of specific histopathology or inciting factors.

Neonatal purpura fulminans: a genetic disorder related to the absence of protein C in blood

To confirm the pathogenesis and the genetic background of neonatal-onset purpura fulminans, two unrelated infants with this rare thrombotic syndrome and 47 of their asymptomatic relatives were studied. In both families, 27 subjects with hereditary partial deficiency of protein C, including both parents of each patient, were identified. The patient in whom it was possible to evaluate protein C directly showed no detectable levels of this plasma component. These findings confirm the linkage of neonatal purpura fulminans to a genetic trait with established mendelian transmission and strongly suggest that the syndrome is an expression of homozygosity for protein C deficiency. The dramatic clinical picture and the type of pathologic change that develops as a result of the lack of circulating protein C emphasize the vital role of this protein in protection from thrombin generation, mainly within the microvascular system. However, our data do not contribute to the evidence that partial familial protein C deficiency is associated with a major risk of venous thromboembolism.

Diabetes and renal calcium binding protein in the rat

Renal calcium binding protein (CaBP), a vitamin D-dependent protein of 28,000 Mr, may be involved in calcium transport by cells of the renal tubule. The streptozotocin-diabetic rat is hypercalciuric and shows markedly decreased concentration of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] in serum and of CaBP in small intestine. To examine the relationship of renal CaBP in diabetes to 1,25-(OH)2D3 and urinary calcium excretion, renal CaBP, serum 1,25-(OH)2D3, and urinary calcium were measured in control, diabetic, and insulin-treated diabetic rats. Treatment of the diabetic rat with insulin decreased urinary calcium excretion and elevated 1,25-(OH)2D3 toward normal. Renal CaBP was found to be the same in controls and diabetics despite a tenfold difference in concentration of 1,25-(OH)2D3 in serum, and to be unaffected by insulin treatment, which elevated 1,25-(OH)2D3 by a factor of 7 above untreated diabetics. It is concluded that in the diabetic rat either (1) the threshold concentration of 1,25-(OH)2D3 for inducing synthesis of renal CaBP is set at a much lower level than that for intestinal CaBP, or (2) since both 1,25-(OH)2D3 and renal CaBP are produced in the kidney, 1,25-(OH)2D3 exerts a paracrine effect on renal CaBP production because of its high local concentration. The increased urinary calcium excretion in the untreated streptozotocin-diabetic rat is not secondary to an alteration in renal CaBP.

Swyer-James syndrome--unilateral hyperlucent lung syndrome. A case report and review

Swyer-James syndrome is a pulmonary condition acquired following bronchiolitis obliterans early in life. Clinically characterized by repeated bouts of pulmonary infections, Swyer-James syndrome is characterized radiographically by a unilateral small, hyperlucent lung that demonstrates diminished arterial supply to the involved lung, air-trapping, and bronchiectasis. Radioimaging procedures may reveal otherwise unsuspected bilateral involvement. A 14-year-old Caucasian female with classic findings of Swyer-James syndrome is presented. The differential diagnosis of conditions that may present with a unilateral hyperlucent lung is discussed. Therapy is aimed primarily at control of the intercurrent episodes of bacterial pneumonia.

Calcium and sodium transport and vitamin D metabolism in the spontaneously hypertensive rat

Serum ionized calcium levels are lower and immunoreactive parathyroid hormone levels are higher in the spontaneously hypertensive (SH) rat than in the normotensive Wistar-Kyoto (WKy) control. We postulated that there is either a defect in the regulation of vitamin D metabolism by parathyroid hormone or that the gut target organ for vitamin D in the SH rat is unresponsive. To test these hypotheses we measured serum concentrations of vitamin D metabolites and intestinal transport of calcium and sodium. Compared with that of WKy controls, in vitro calcium transport by duodenal sacs of the SH rat was decreased (P less than 0.001) at 5 wk, before the development of hypertension, and at 12 wk, after hypertension was well established. When measured in vivo in the most proximal 20 cm of small intestine, maximum velocity (Vmax) for calcium transport was decreased (P less than 0.05) and net absorption of sodium and water was increased (P less than 0.05) in SH rats as compared with WKy rats. Vmax for calcium transport was also decreased (P less than 0.05) in the most distal 20 cm of small intestine of SH rats, but net sodium and water transport were the same in SH and WKy rats. At 12 wk, serum concentration of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] was the same in both SH and WKy groups, but its precursor, 25-hydroxycholecalciferol, was increased (P less than 0.05) in the SH rat. We conclude that in the SH rat: (a) the concentration of 1,25-(OH)2D3 is inappropriately low in relation to the elevated immunoreactive parathyroid hormone and the depressed calcium absorption, suggesting a defect in the regulation of vitamin D metabolism; and (b) the depressed calcium absorption, in the setting of normal concentrations of [1,25-(OH)2D3], demonstrates unresponsiveness of the gut to vitamin D and may explain in part the low serum ionized calcium found in earlier studies. The presence of these abnormalities before we found a significant difference in blood pressure suggests that they may be causal, not secondary, to the hypertension.

Gentamicin and tobramycin pharmacokinetics in patients with cystic fibrosis

Pharmacokinetic variables were compared in patients with cystic fibrosis receiving gentamicin or tobramycin for the treatment of a pseudomonas pulmonary infection. Sixty-nine pediatric patients receiving gentamicin sulfate (n = 31) or tobramycin sulfate (n = 38) were studied. Doses were administered every six hours. All patients received concurrent ticarcillin therapy, had a mild fever, and normal hematocrit and serum creatinine values. Amino-glycoside pharmacokinetic variables were calculated. Tobramycin and gentamicin serum concentrations were determined by radioimmunoassay. The mean (+/- S.D.) half-lives for the tobramycin and gentamicin patients were 1.2 +/- 0.5 and 1.4 +/- 0.4 hr, respectively. The average volume of distribution and clearance values for the tobramycin and gentamicin patients were 0.33 +/- 0.20 liters/kg and 2.98 +/- 0.80 ml/min/kg, and 0.35 +/- 0.15 liters/kg and 2.79 +/- 0.75 ml/min/kg, respectively. There were no significant differences between the kinetic variables in the patients receiving gentamicin or tobramycin. To achieve steady-state peak concentrations between 7 and 9 micrograms/ml and trough concentrations below 2 micrograms/ml, gentamicin patients required 10.3 +/- 3.2 mg/kg/day and tobramycin patients required 11.1 +/- 3.9 mg/kg/day. Because of the large amount of interpatient variability in maintenance dosage requirements, therapy should be initiated with 2.5 mg/kg of gentamicin or tobramycin given every six hours and then individualized on the basis of serum concentrations and clinical response.

Elevated intestinal disaccharidase activity in the streptozotocin-diabetic rat is independent of enteral feeding

Specific and total activities of the disaccharidases, sucrase, maltase, and lactase are increased in mucosa of the small intestine of the streptozotocin diabetic rat. Because disaccharidases are essential for terminal digestion of carbohydrate, and disaccharidase deficiency is a common clinical problem, understanding the mechanisms regulating disaccharidase activity is important. In normal animals, disaccharidase activities are determined by route of feeding and are decreased by parenteral feeding. The indirect exocrine, endocrine, neurocrine, and paracrine functions of the gastrointestinal tract that are dependent on feeding via the gut are greatly decreased in parenteral as compared with enteral feeding. Hormone secretion by the gut and the pattern of response after feeding may be abnormal in diabetes and might be regulatory for disaccharidases. We tested the hypothesis that the elevated intestinal disaccharidases in diabetes are dependent on enteral feeding. Streptozotocin-injected rats (diabetics) and vehicle-injected rats (controls) were fed rat chow ad libitum for 4 days. A subset of control and diabetic animals was then killed to determine disaccharidase activity of the jejunum at the start of pair-feeding the elemental diet. The remaining animals were fed 60 cal/day of glucose, amino acid (Travasol), and electrolyte solution either intragastrically or intravenously for 4 days. Specific and total activities of disaccharidases were greater in diabetics than in controls under all feeding conditions. In controls, the pattern of activity of disaccharidase specific activity was initial greater than intragastric greater than intravenous. In diabetics, disaccharidase specific activities did not differ among groups. In both controls and diabetics, mean mucosal mass was highest initially; intermediate with intragastric feeding; and lowest with intravenous feeding. In both controls and diabetics, total disaccharidases decreased from initial to intragastric to intravenous. We conclude: (1) disaccharidase specific activity in controls is sensitive to feeding route and nature of diet, but is nearly independent of these factors in diabetics; (2) total disaccharidase activities respond to feeding stimuli in parallel with changes in mucosal mass in both controls and diabetics; and (3) the lack of feeding effect on the elevated specific activities of disaccharidases in diabetes suggests that this elevation is a response to the diabetic state and is independent of enteral factors such as luminal nutrition and gastrointestinal hormones.

Rat large bowel maintains calcium transport after small bowel resection

Because of the marked defect in calcium transport by the residual duodenum and ileum of the rat 10 days after 70% resection of mid-small intestine, we examined the calcium transport response by large intestine at this time. Although net cecal calcium absorption was decreased by one third in resected rats as compared with transected controls, total net cecal absorption was maintained because of the small growth response. Colonic calcium transport was the same in transected and resected groups, despite greater segment growth in the resected group. In comparison to the marked abnormality in calcium transport by the residual small intestine secondary to resection, the effect on the large intestine was minimal.

Superoxide dismutase activity in the intestine of the streptozotocin-diabetic rat

Insulin stimulates the production of superoxide and hydrogen peroxide in various tissues. Hydrogen peroxide has been proposed to be an intracellular second messenger for insulin and a moderator of cellular proliferation and differentiation. We previously found that cell proliferation is increased in small intestinal mucosa of streptozotocin-diabetic rats. The current study was undertaken to determine if superoxide dismutase (SOD), the enzyme that converts superoxide to hydrogen peroxide, is altered in the mucosa of the alimentary tract and renal cortex of the diabetic rat, and if so, whether SOD responds to insulin treatment. Total SOD and cyanide-insensitive [manganese-containing SOD (Mn SOD)] SOD were measured by the nitroblue tetrazolium inhibition assay. We studied ad libitum fed animals, where diabetics are hyperphagic and pair-fed animals, where hyperphagia is not present. Since cyclic nucleotides appear to control cell proliferation in some tissues, we also measured cAMP and cGMP in mucosa of the small intestine. In ad libitum fed animals, total SOD was depressed in the mucosa of duodenum, jejunum, and ileum, but not in the cecum or colon of the streptozotocin-diabetic rats. The level of Mn-SOD was not affected by diabetes or insulin treatment, but the cyanide-sensitive [copper- and zinc containing SOD (Cu-Zn SOD] SOD was depressed in the small intestine and colon of diabetic rats. Insulin treatment restored total and Cu-Zn SOD activity in the small intestine to normal and increased Cu-Zn SOD activity in the colon to normal. Pair-fed animals showed the same changes in the SOD activity of jejunal mucosa that were found in ad libitum fed animals. In renal cortex, diabetes did not alter total SOD, but increased Mn SOD and decreased Cu-Zn SOD. Both responses were reversed by insulin treatment. Cyclic nucleotide concentrations were not affected by diabetes. We conclude that SOD enzymes re altered in diabetes, at least in proliferating tissues. Responses are tissue specific. The mucosa of the small intestine and colon show decreased Cu-Zn SOD, the SOD of the cecum is unaffected, and the kidney shows increased Mn SOD and decreased Cu-Zn SOD. The SOD responses of diabetics are reversed by insulin treatment.

Calcium intake regulates 1,25-dihydroxy-vitamin D formation in the diabetic rat

Duodenal calcium absorption and serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations are decreased and body growth is arrested in the streptozotocin-diabetic rat taking commercial chow with high (1.2-2%) calcium content. Treatment with insulin restores 1,25-(OH)2D3, calcium absorption, and body growth to normal. We hypothesized that the depressed 1,25-(OH)2D3 in diabetics is due in part to the minimal requirement for vitamin-D-mediated intestinal calcium transport under conditions of arrested growth and high calcium intake. We tested this hypothesis by comparing the response of serum 1,25-(OH)2D3 concentration to low (0.02%) and normal (0.5%) calcium diets in control and streptozotocin-diabetic rats. To evaluate response to short-term insulin treatment, serum 1,25-(OH)2D3 was measured after 12 or 36 h of treatment. Serum 1,25-(OH)2D3 concentrations in the 0.5% calcium diet groups were 175, 25, and 120 pg/ml for control, diabetic, and insulin-treated 36-h groups, respectively. Low calcium diets increased concentration to 625, 100, and 370 pg/ml for controls, diabetics, and insulin-treated 36-h groups, respectively. In conclusion, the diabetic retains the ability to respond to calcium deficiency, even in the insulin-deficient state. Low calcium intake, in addition to enhancing 1,25-(OH)2D3 formation in diabetics, also modulates the response to insulin treatment. These studies demonstrate that the regulatory factor(s) suppressing serum, 1,25-(OH)2D3 in diabetes is not simply insulin deficiency per se. Implications of these findings for diabetes are discussed.

Gastrin and growth of the alimentary tract in the streptozotocin-diabetic rat

Mucosal growth in small intestine of the streptozotocin-diabetic rat is increased; insulin treatment decreases growth toward normal. Gastrin is trophic to the alimentary tract. Therefore, we measured gastrin and growth of the alimentary tract in controls, diabetics, and insulin-treated diabetics. Mucosal growth of the small intestine increased at 10 days of diabetes and increased further by 20 days. Serum and antral gastrin did not respond to diabetes at 10 days. At 20 days, mean antral gastrin was increased in all diabetic groups, but the increase was significant only for a hyperphagic ad libitum-fed diabetic group, which also showed increased serum gastrin. Insulin treatment decreased serum gastrin but only partly reversed the increased mucosal growth in diabetics. We conclude that 1) gastrin is not the primary cause for increased small intestinal mucosal growth in diabetes, inasmuch as gastrin did not respond to diabetes at 10 days when mucosal growth was increased, and decreased serum gastrin in insulin-treated groups was associated with increased mucosal growth; and 2) diabetes appears to increase gastrin.

Intraventricular cerebrospinal fluid antibiotic concentrations in patients with intraventricular infections

The antibiotic concentration of the fluid from either lateral ventricle was determined 104 times in 37 patients through direct ventricular puncture, external ventricular drainage (EVD), or cerebrospinal fluid shunt sampling. The patients were 1 month to 12 years old. When the patients were receiving maximal intravenous antibiotic therapy alone, the concentrations for the most part were below 5 microgram/ml, whereas patients receiving an antibiotic through direct ventricular puncture, EVD, or a shunt reservoir usually had concentrations over 5 microgram/ml. However, wide variations from patient to patient were found with all forms of treatment despite similar dosages. Clustering of the concentration tended to occur in each individual patient. The authors conclude that, to obtain a high concentration of an antibiotic in the ventricular fluid, one should administer it directly into the ventricle.

The management of cerebrospinal fluid shunt infections: a clinical experience

Fifty patients with infected cerebrospinal fluid shunts were treated by one of three forms of treatment: a) Twenty-two patients had shunt removal, systemic antibiotic treatment, and either external ventricular drainage or intermittent ventricular taps for decompression and antibiotic administration. b) Seventeen patients had removal and immediate replacement of the shunt with intrashunt and systemic antibiotics. c) Eleven patients received intrashunt and systemic antibiotics without shunt removal. In the first group, antibiotics were given for a period of one week; in the second and third groups, intravenous antibiotics were administered for a minimum period of three weeks, and intraventricular antibiotics twice daily for two weeks. In all patients ventricular CSF was obtained and cultured 48 hours after cessation of antibiotic therapy, and cultures were repeated within four months after completion of therapy. Twenty-one of 22 patients in the first group as well as 11 of 13 of the second group, were successfully treated. In the third group only four of the 11 patients responded to treatment.