Radical pancreatoduodenectomy for misdiagnosed pancreatic mass

Occasionally pancreatoduodenectomy is performed for clinically suspected pancreatic malignancy only for the surgeon to find that a benign aetiology accounts for the pancreatic mass. The aim of this study was twofold: to determine the incidence of pancreatoduodenectomy performed for a misdiagnosis of pancreatoduodenal malignancy and to identify potentially avoidable errors in preoperative and intraoperative judgement. Between 1956 and 1990, radical pancreatoduodenectomy was performed in 603 patients at the Mayo Clinic; 29 (5 per cent) underwent pancreatoduodenectomy for a diagnosis made before and during surgery of primary pancreatic or periampullary malignancy that was later proven histopathologically to be either unsuspected subacute or chronic pancreatitis (22 patients), benign fibrous common bile duct stricture (two), and penetrating duodenal ulcer, metastatic melanoma, ampullary adenoma, intrahepatic drug-induced cholestasis and pseudocyst (one each). No patient had a preoperative diagnosis of chronic pancreatitis. Weight loss, pain and/or jaundice were present in 27 of the 29 patients. Objective imaging tests, such as computed tomography, ultrasonography and/or endoscopic retrograde cholangiopancreatography, were performed in 25 patients. Potential errors in judgement may be avoided by a more aggressive attempt at biopsy in selected patients; in others, resection for presumed malignancy may be unavoidable.

Plasmodium coatneyi-infected rhesus monkeys: a primate model for human cerebral malaria

Although several animal models for human cerebral malaria have been proposed in the past, none have shown pathological findings that are similar to those seen in humans. In order to develop an animal model for human cerebral malaria, we studied the pathology of brains of Plasmodium coatneyi (primate malaria parasite)-infected rhesus monkeys. Our study demonstrated parasitized erythrocyte (PRBC) sequestration and cytoadherence of knobs on PRBC to endothelial cells in cerebral microvessels of these monkeys. This is similar to the findings seen in human cerebral malaria. Cerebral microvessels with sequestered PRBC were shown by immunohistochemistry to possess CD36, TSP and ICAM-1. These proteins were not evident in cerebral microvessels of uninfected control monkeys. Our study indicates, for the first time, that rhesus monkeys infected with P. coatneyi can be used as a primate model to study human cerebral malaria.

On the pH-dependent yield of hydroxyl radical products from peroxynitrite

Nitric oxide reacts rapidly with superoxide to give the strongly oxidizing peroxynitrite anion (ONOO-), which undergoes spontaneous first-order decomposition when protonated. The oxidative chemistry of peroxynitrite (ONOO-) is highly pH-dependent. At acidic pH, peroxynitrous acid (ONOOH) oxidizes dimethylsulfoxide to formaldehyde and 2,2'-azino-bis-(3-ethyl-1,2- dihydrobenzothiazoline 6-sulfonate) (ABTS) to the greenish-colored ABTS+ radical cation. The product yield from dimethylsulfoxide and ABTS decreased at more alkaline pH with apparent pK(a)s of 7.9 and 8.2, respectively. Decreasing yield with increasing pH could not be explained by the oxidation of either formaldehyde or ABTS+ by peroxynitrite. In the presence of 50 mM dimethylsulfoxide, nitrogen dioxide was formed in approximately equimolar amounts to the other reaction product, formaldehyde. The yield of nitrogen dioxide also decreased with an apparent pK(a) of 8.0. We propose that the complex oxidative chemistry of peroxynitrite is controlled by the pH-dependent isomerization of the relatively stable cis-configuration (predominant at high pH) to the trans-configuration. Trans-peroxynitrous acid can form a vibrationally excited intermediate capable of reacting like hydroxyl radical. The vibrationally excited intermediate can also directly rearrange to nitric acid, reducing the apparent hydroxyl radical yield to less than 30%. The loss of hydroxyl radical-like reactivity can be explained on the basis of ionization of trans-peroxynitrous acid to the trans-anion, which in turn undergoes internal rearrangement to nitrate without forming a strong oxidant.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Diaminopyridine reverses respiratory paralysis induced by a presynaptically active snake venom and its major neurotoxin

Presynaptically active snake venom neurotoxins induce a potentially fatal neuromuscular blockade which cannot be reliably overcome by current therapy. The drug 3,4-diaminopyridine (DAP) is effective in other presynaptic paralytic conditions and was therefore tried in anaesthetized rabbits with respiratory paralysis induced by krait (Bungarus fasciatus) venom. A strain gauge pneumograph measured rabbit chest circumference during the respiratory cycle to document objectively effects of toxins and treatments. DAP counteracted the effects of both whole krait venom and its purified presynaptically active component, beta-bungarotoxin. Respiratory excursions increased within 4-8 min after DAP injection in animals paralysed with beta-bungarotoxin and 4-10 min after the injection of DAP in animals paralysed with 1 mg/kg whole krait venom. The onset of complete respiratory paralysis after a lethal dose of whole krait venom (2 mg/kg) was delayed significantly by DAP. This is the first indication that presynaptic venom paralysis can be reversed and suggests that DAP merits further evaluation as treatment for this condition.

Prospective evaluation of gastric acid secretion and cobalamin absorption following gastric bypass for clinically severe obesity

The pathophysiologic mechanism(s) responsible for cobalamin deficiency after Roux-en-Y gastric bypass for clinically severe obesity remains unexplained. Inadequate secretion of intrinsic factor has been postulated, but decreased gastric acid secretion resulting in maldigestion and inadequate liberation of free cobalamin from its native protein-bound form is also possible. The aim of this study was to determine prospectively secretion of gastric acid and absorption of crystalline (free) and protein-bound cobalamin before and after gastric bypass. Eight patients (two men, six women) underwent orogastric intubation of the intact stomach preoperatively and the proximal gastric pouch postoperatively. Gastric acid secretion in the basal and stimulated (pentagastrin, 6 micrograms/kg) states was determined by a perfused, nonabsorbable marker technique to quantitate recovery of gastric secretion. Absorption of radiolabeled (57Co) crystalline and protein-bound cobalamin was assessed on separate days by 24-hr urinary excretion. After gastric bypass, acid secretion (mean +/- SEM) was markedly reduced in basal (9.1 +/- 3.6 vs 0.005 +/- 0.003 meq/hr; P = 0.04) and stimulated (12.8 +/- 1.8 vs 0.008 +/- 0.003 meq/30 min; P = 0.002) states. Absorption of crystalline cobalamin was decreased (15.8 +/- 2.5 vs 9.4 +/- 1.4%; P = 0.08) to a lesser extent than was protein-bound cobalamin (5.9 +/- 1.0 vs 1.1 +/- 0.3%; P = 0.004). In summary, gastric acid secretion from the gastric pouch is negligible after gastric bypass, and food-bound cobalamin is maldigested and subsequently malabsorbed presumably due to pouch achlorhydria. Decreased absorption of free cobalamin suggests decreased cobalamin-intrinsic factor complex formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Paired box gene expression in Wilms' tumor

Wilms' tumor (WT) is an embryonal renal neoplasm with features resembling fetal kidney development. A family of genes potentially involved in WT induction is called the paired box (PAX) gene family. In this study we examined by Northern blot analysis the expression of several PAX genes in a variety of WTs and other childhood neoplasms. RNA was isolated from four primary WTs and 12 WTs propagated in nude mice (heterotransplant), as well as from a variety of other childhood renal and nonrenal embryonal tumors. RNA samples were electrophoretically separated in 1.2% agarose gels, transferred to nylon membranes, and hybridized to random primer-labeled PAX2, PAX8, and WT1 probes. Membranes were then exposed to x-ray films at -70 degrees C with intensifying screens. PAX2 and WT-1 expression were seen in all four primary WTs; PAX8 was seen in three of the four primary WTs. Of the 12 heterotransplant Wilms' tumors, PAX2, PAX8, and WT1 were concomitantly expressed in seven tumors. Another heterotransplant WT expressed WT1 alone. Expression of these three genes, with one exception, was not seen in the other childhood renal and nonrenal solid tumors. The PAX genes are transcriptional regulators; their protein products bind to specific DNA segments and control gene expression. Their role in the pathogenesis of Wilms' tumor and their interaction with WT1 are unclear. Elucidation of the functional significance of the PAX genes will provide important insights into not only the pathogenesis of WT but also the molecular control of the developing kidney.

Impact of laparoscopic cholecystectomy on the management of cholelithiasis in children with sickle cell disease

Children with sickle cell disease, well known to have a high incidence of cholelithiasis, are frequently admitted to the hospital for episodes of abdominal pain. Before the advent of laparoscopy, few children with sickle cell and cholelithiasis underwent cholecystectomy unless absolutely necessary, because of the high morbidity of an open cholecystectomy (OC). We reviewed our records of all children with sickle cell disease and cholelithiasis treated from 1985 to 1992 to investigate the impact of laparoscopic cholecystectomy (LC). During that period, 32 children underwent cholecystectomy: 10 OC and 22 LC (all since December 1990). Before December 1990, all children had either classic biliary tract symptoms or abdominal pain of unknown etiology. However, of the 22 LC children, five had asymptomatic cholelithiasis. Only three of the 32 patients had choledocholithiasis, although 30 of 32 had elevated total bilirubins. Two LC children presented with choledocholithiasis and were initially treated with endoscopic sphincterotomy and stent placement. A standard intraoperative cholangiogram (IOC) through the cystic duct was performed in all OC cases. In 19 of 22 LC cases, an IOC through the gallbladder was performed before any dissection; unsuspected choledocholithiasis was not found, but the IOC did allow visualization of the course of the cystic duct, facilitating its subsequent dissection. Total operative length was comparable between the two groups, but the LC patients' postoperative length of stay was half that of the OC patients (2.1 v 4.6 days). Postoperative complications in the OC group included three children who had severe pain, atelectasis, fever, and hypoxemia (30%).

Tracheoesophageal compression from aortic arch anomalies: analysis of 30 operatively treated children

During a 16-year period (1976 to 1992), 30 children underwent surgery for tracheoesophageal compression caused by aortic arch anomalies. The age range was 3 days to 12 years (median, 3 months); 19 (63%) were male, and 20 (67%) were white. Of the 30 patients, 10 had a double aortic arch (the left was atretic in 6), 5 had a left-sided arch with an aberrant right subclavian artery (4) or innominate artery (1), and 15 had a right-sided arch with an aberrant left subclavian artery (14) or with mirror-image branching (1). There was no mortality during hospitalization or within 30 days of surgery. The left ductus arteriosus was divided in 26 of the 30 patients. Among the 10 patients with a double aortic arch, division of the atretic left arch (6), the lesser left arch (3), or the lesser right arch (1) was carried out. All 4 patients with a left arch and aberrant right subclavian artery had division of the artery. Of 14 patients with a right arch and aberrant left subclavian artery, only 3 underwent division of the artery. Of the 30 patients, anterior arteriopexy was performed in 9 (30%), and reoperation for persistent symptoms was necessary in 4 (13%). The second operation usually consisted of aortopexy or tracheopexy. Of the 4 patients with associated cardiac anomalies, 2 underwent simultaneous cardiac repair. The duration of hospital stay for the 30 patients ranged from 4 to 148 days (median, 6 days). Excluded from this series are patients with vascular rings who were asymptomatic and patients with the pulmonary vascular sling syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic embolism in thyrotoxicosis without cardiac arrhythmia

A 39-year-old woman presented with an acute left hemisphere stroke and was found to have severe hyperthyroidism. She developed an acute right brachial artery occlusion while under continuous cardiac monitoring, and at no time exhibited atrial fibrillation. This case, and a review of the literature, suggests that thromboembolism occurs in thyrotoxicosis without atrial fibrillation.

Magnetic resonance imaging in ochronosis, a rare cause of back pain

A 34-year-old man had progressive, poorly controlled low back pain for 3 years before testing confirmed a diagnosis of ochronosis. This is the first case description of the magnetic resonance imaging (MRI) appearance of spinal ochronosis, which should be considered when advanced degenerative change is seen on spinal MRI in young individuals.

Diagnosis of Helicobacter pylori infection in a developing country: comparison of two ELISAs and a seroprevalence study

Serology to detect antibodies to Helicobacter pylori is not frequently used as a diagnostic tool in developing countries. When compared to a commercial ELISA, an ELISA constructed and validated in Thailand had a higher sensitivity (98% vs. 85%), specificity (76% vs. 66%), and negative predictive value (97% vs. 76%) for the detection of H. pylori infection among 104 patients with dyspepsia evaluated by endoscopy. The positive predictive value was 88% for both tests. Serum antibody levels fell significantly 5-8 months after eradication of infection in 8 Thai patients (P = .009). By 8 years of age, > 50% of Thai persons living in urban and rural locations were seropositive. The low negative predictive value of the commercial ELISA limits the usefulness of this assay as a diagnostic tool in Thailand and suggests a need to reevaluate H. pylori serologic tests when used in populations living in developing countries.

A nonhuman primate model for human cerebral malaria: effects of artesunate (qinghaosu derivative) on rhesus monkeys experimentally infected with Plasmodium coatneyi

We studied the effects of artesunate on rhesus monkeys infected with Plasmodium coatneyi. Sixteen rhesus monkeys were divided in four groups. Group I consisted of three monkeys that were splenectomized and were treated with three doses (loading dose: 3.3 mg/kg, maintenance doses: 1.7 mg/kg) of artesunate, group II consisted of three monkeys that were treated with three doses of artesunate (same as group I), group III consisted of two monkeys that were treated with one dose (3.3 mg/kg) of artesunate, and group IV consisted of five untreated monkeys. Parasitemias of these groups ranged from 13.3% to 19.5% before treatment. Twenty-four hours after administration, the parasitemia was reduced to 2.2% in group I and to < 0.1% in group II; parasitemia was lowered to 10.6% in group III only 3 hr after drug administration. The rate of sequestration in the cerebral microvessels, which was 29.4% in untreated animals, was < 0.1% in groups I and II (24 hr after treatment), and 2.0% in group III (3 hr after treatment). These data clearly indicate that artesunate not only reduced parasitemia, but also reduced the rate of parasitized red blood cell (PRBC) sequestration in cerebral microvessels. In an immunohistologic study, endothelial-leukocyte adhesion molecule-1 (ELAM-1) was not detected in group I after treatment with artesunate, although the presence of CD36, thrombospondin, intercellular adhesion molecule-1, IgG, and C3 in the cerebral microvessels was not altered. This is the first in vivo study to show that artesunate interferes with continued PRBC sequestration in the cerebral microvessels in cerebral malaria.(ABSTRACT TRUNCATED AT 250 WORDS)

Hanford miniature swine model for extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is now an accepted therapy for neonatal respiratory failure due to reversible lung disease. There is a continued need to train ECMO team members using animal models. Hanford miniature swine are an appropriate model for this purpose because of the availability and size as well as anatomic and physiologic similarities to humans. This article describes training ECMO team members in venoarterial and venovenous bypass utilizing Hanford miniature swine.

Reoperative bariatric surgery. Lessons learned to improve patient selection and results

OBJECTIVE

The purpose of this study was to determine the spectrum of presentation, safety, and efficacy of operative bariatric surgery.

SUMMARY BACKGROUND DATA

The only lasting therapy for medically complicated clinically severe obesity is bariatric surgery. Several operative approaches have resulted in disappointing long-term weight loss or an unacceptable incidence of complications that require revisionary surgery.

METHODS

Sixty-one consecutive patients who underwent reoperative bariatric surgery from 1985 to 1990 were observed prospectively. One, two, or three previous bariatric procedures had been performed in 77%, 18%, and 5% of patients, respectively. Reoperation was required for unsatisfactory weight loss after gastroplasty or gastric bypass (61%), metabolic complications of jejunoileal bypass (23%), or other complications (16%), including stomal obstruction, alkaline- or acid-reflux esophagitis, and anastomotic ulcer. Revisionary procedures included conversion to vertical banded gastroplasty (33% of operations) and vertical Roux-en-Y gastric bypass (52% of operations); partial pancreato-biliary bypass was used selectively in four patients with severe, medically complicated obesity.

RESULTS

A single patient died postoperatively of a pulmonary embolus; serious morbidity occurred in 11%. Weight loss (mean +/- SEM) after reoperation for unsuccessful weight loss was greater with gastric bypass than with vertical banded gastroplasty (54 +/- 6% versus 24 +/- 6% of excess body weight). Metabolic complications of jejunoileal bypass were corrected, but 67% of the patients were dissatisfied with their postoperative lifestyle because of changes in eating habits or weight gain (64% of patients). Stomal complications and esophageal reflux symptoms were reversed in all patients.

CONCLUSIONS

Reoperative bariatric surgery in selected patients is safe and effective for unsatisfactory weight loss or for complications of previous bariatric procedures. Conversion to gastric bypass provides more effective weight loss than vertical banded gastroplasty.

Causal prophylactic and radical curative activity of WR182393 (a guanylhydrazone) against Plasmodium cynomolgi in Macaca mulatta

Primaquine is the only currently available drug effective against persistent tissue stages of relapsing malaria in humans. Causal prophylactic and radical curative properties of WR182393 (a guanylhydrazone) were investigated as part of an effort to evaluate alternatives to primaquine in the rhesus monkey (Macaca mulatta)/Plasmodium cynomolgi test model. The drug was suspended in dimethylsulfoxide for intramuscular (im) injection. A pilot study indicated causal prophylactic activity in a regimen of 40 mg base/kg/day im for three days beginning the day before intravenous challenge with 1 x 10(6) P. cynomolgi sporozoites. Regimens of 31, 10, 3.1, and 0 mg base/kg/day im for three days were then tested in groups of two monkeys given a similar challenge. The two animals given 31 mg base/kg/day remained parasite-free. Average time to parasitemia for the lower dosage groups was 38, 18, and 8 days respectively. Groups of two monkeys with sporozoite-induced P. cynomolgi infections were also treated for seven days with 31, 10, 3.1, and 0 mg base/kg/day im in combination with 10 mg base/kg/day of chloroquine orally. Both monkeys given 31 mg base/kg/day did not relapse. The average time to relapse following treatment was 48, 29, and 8 days, respectively, for the lower dosage groups. Compound WR182393 is the first non-8-aminoquinoline class of drug to exhibit both causal prophylactic and radical curative properties against a relapsing primate, vivax-like malaria.

Sequestration pattern of parasitized erythrocytes in cerebrum, mid-brain, and cerebellum of Plasmodium coatneyi-infected rhesus monkeys (Macaca mulatta)

Six rhesus monkeys (Macaca mulatta) infected with Plasmodium coatneyi were studied for parasitized red blood cell (PRBC) sequestration in microvessels of the brain. The degree of PRBC sequestration is different in the cerebral, mid-brain, and cerebellar microvessels, with sequestration occurring preferentially in the cerebellum. This pattern resembles that of PRBC sequestration in cerebral and cerebellar microvessels in human falciparum malaria. The morphologic appearance of sequestered cells under light and electron microscopy as well as the PRBC sequestration pattern bolsters the contention that the rhesus monkey infected with P. coatneyi is an appropriate primate model for the experimental study of human cerebral malaria.

Effect of alpha-methylnorepinephrine, an alpha 2-adrenergic agonist, on jejunal absorption in neurally intact conscious dog

Although alpha 2-adrenergic agonists stimulate absorption in the mammalian small and large intestine in vitro, the possibility of central neural effects have confounded interpretation of in vivo studies. Our aim was to assess the effects of intravenous administration of alpha-methylnorepinephrine (MNE), an alpha 2-adrenergic agonist that does not cross the blood-brain barrier, on net jejunal absorption of water and electrolytes in the neurally intact, conscious dog. Absorption from a 30-cm proximal jejunal segment was studied using a triple-lumen perfusion technique in seven dogs. A warmed, isosmolar, balanced electrolyte solution containing [14C]polyethylene glycol was infused at 5 ml/min. Net jejunal fluxes of water and electrolytes were determined before, during, and after a 1.5-hr infusion of MNE (900 nmol/kg/hr). MNE increased net jejunal water absorption (from 12.9 +/- 1.8 to 22.5 +/- 1.5 microliters/cm/min, P < 0.05). Peripheral alpha 2-adrenergic receptors mediate a net proabsorptive response in the neurally intact canine jejunum in vivo independent of direct central neural effects.

Three-dimensional structure of influenza A N9 neuraminidase and its complex with the inhibitor 2-deoxy 2,3-dehydro-N-acetyl neuraminic acid

We present here the three-dimensional structure of neuraminidase (E.C. 3.2.1.18) from influenza virus A/Tern/Australia/G70c/75 (N9), determined by the method of multiple isomorphous replacement, and the structure of the neuraminidase complexed with an inhibitor, 2-deoxy-2,3-dehydro-N-acetyl neuraminic acid (DANA). Native and inhibitor complex crystals are isomorphous and belong to space group I432 with unit cell dimensions of 183.78 A. The native enzyme structure and the inhibitor complex structure have been refined at 2.5 A and 2.8 A resolution, respectively, with crystallographic R-factor values of 0.193 for the native enzyme, and 0.179 for the inhibitor complex. The current enzyme model includes 387 amino acid residues which comprise the asymmetric unit. The root-mean-square deviation from ideal values is 0.013 A for bond lengths and 1.6 degree for bond angles. The neuraminidase (NA), as proteolytically cleaved from the virus, retains full enzymatic and antigenic activity, and is a box-shaped tetramer with edge lengths of 90 A and a maximal depth of 60 A. The NA tetramers are composed of crystallographically equivalent monomers related by circular 4-fold symmetry. Each monomer folds into six antiparallel beta-sheets of four strands. The secondary structure composition is 50% beta-sheet. The remaining 50% of the residues form 24 strand-connecting loops or turns. One of the loops contains a small alpha-helix. The structure of the complex of NA with DANA, a transition state analog, has enabled us to identify and characterize the site of enzyme catalysis. The center of mass of bound inhibitor is 32 A from the 4-fold axis of the tetramer, lodged at the end of a shallow crater of diameter 16 A with a depth of 8 to 10 A. There are 12 amino acid residues that directly bind DANA, with a further six conserved amino acids lining the active site pocket. The neuraminidase inhibitor complex provides a three-dimensional model which will be used to further the understanding of enzymatic hydrolysis and aid the design of specific, antineuraminidase antiviral compounds.

Metabolic disturbances in Plasmodium coatneyi-infected rhesus monkeys

To investigate metabolic disturbances in an animal model of human malaria, four rhesus monkeys (Macaca mulatta) were infected with Plasmodium coatneyi, a parasite which induces cytoadherence of infected erythrocytes. When moribund or the parasitaemia had plateaued, the monkeys were sacrificed (3 animals) or treated with chloroquine (1 animal). Blood and cerebrospinal fluid (CSF) were sampled at intervals between inoculation and sacrifice or treatment. Arterial and CSF glucose and lactate rose during infection, indicating evolving insulin resistance. The arteriovenous difference in glucose concentration also increased, consistent with increased glucose consumption by parasitised tissues. Arterial plasma lactate rose but a positive arteriovenous concentration difference suggested tissue lactate uptake. The animal with the highest plasma lactate at sacrifice remained hyperglycaemic but also had the highest CSF lactate, the greatest cerebral sequestration and neurological depression, and biochemical and histological evidence of severe hepatic pathology. Serum cholesterol and corrected serum calcium fell consistently during infection; serum phosphate was also reduced in animals without renal impairment. These preliminary results indicate that lactic acidosis is a late complication of severe malaria and, by implication from this and other studies, hypoglycaemia occurs even later; other metabolic changes during P. coatneyi infection in rhesus monkeys also parallel those of severe falciparum malaria in humans. The model could be used in further studies of malaria-associated metabolic dysfunction and its management.

Gastric acid secretion and vitamin B12 absorption after vertical Roux-en-Y gastric bypass for morbid obesity

OBJECTIVE

This study sought to determine the basal and peak-stimulated acid secretion from the proximal gastric pouch and its relationship to absorption of free and food-bound vitamin B12 after gastric bypass for morbid obesity.

SUMMARY BACKGROUND DATA

Gastric bypass can be performed safely and provides acceptable weight loss, but concerns remain about possible long-term complications such as vitamin B12 malabsorption. The authors hypothesized that by constructing a small pouch of gastric cardia, acid secretion into the pouch would be low, leading to maldigestion of food-bound vitamin B12 with subsequent malabsorption.

METHODS

Basal and pentagastrin-stimulated peak acid outputs from the proximal gastric pouch were measured in ten patients after vertical Roux-en-Y gastric bypass using a perfused orogastric tube technique. Absorption of free and food-bound 57Co-vitamin B12 was evaluated separately using 24-hour urinary excretion.

RESULTS

Basal (mEq/hr, mean +/- standard error of the mean [SEM]) and peak-stimulated (mEq/30 min) acid secretions from the proximal gastric pouch were markedly decreased compared to those for age- and sex-matched hospital control subjects (0.01 +/- 0.01 vs. 4.97 +/- 0.66 and 0.08 +/- 0.04 vs. 12.11 +/- 1.34, respectively; p < 0.001 for each). While absorption of free vitamin B12 was not statistically different from that of control subjects (11 +/- 2 vs. 15 +/- 2%; p > 0.05), absorption of food-bound vitamin B12 was decreased (0.8 +/- 0.2 vs. 3.7 +/- 0.5%; p < 0.01).

CONCLUSIONS

After vertical Roux-en-Y gastric bypass for morbid obesity, acid secretion is virtually absent and food-bound vitamin B12 is maldigested and subsequently malabsorbed. The results of this study suggest that postoperative vitamin B12 supplementation is important and can be achieved with either monthly parenteral vitamin B12 or daily oral crystalline preparations.

Plasmodium coatneyi ring-infected erythrocyte surface antigens

Plasmodium coatneyi produced ring-infected erythrocyte surface antigen (RESA) during infection of the rhesus monkey. This antigen was immunogenic and elicited an antibody response that was not persistent but was boosted by repeated infections in a manner similar to that seen in P. falciparum infections in humans. Preliminary data showed that the appearance and increasing titer of antibodies to P. coatneyi RESA-like antigen were associated with prolongation of intervals from inoculation to patency and with control of parasitemia. Studies using both immunofluorescence assay and Western blot analysis showed that P. coatneyi-immune rhesus serum cross-reacted with P. falciparum antigens, but P. falciparum immune human serum did not recognize P. coatneyi antigens in either assay. These results show that P. coatneyi expresses RESA-like antigen that elicits an antibody response similar to that observed for human antibody to P. falciparum RESA. However, antibodies to P. coatneyi did not cross-react with P. falciparum RESA in erythrocyte membrane immunofluorescence assay and dot immunoblot analysis, suggesting that different immunogenic epitopes are present on the two molecules. Our observations support the use of this primate model in RESA-based vaccine development.

Barrett's esophagus in children. Diagnosis and management

OBJECTIVE

To determine the local prevalence and optimal therapy for children with Barrett's esophagus (BE), the authors studied children with esophageal strictures or gastroesophageal reflux (GER), or both, to diagnose BE and to follow after therapy.

SUMMARY BACKGROUND DATA

Barrett's esophagus is seldom reported in children and therapeutic recommendations are unclear. Barrett's esophagus usually develops during the mucosal reparative process after acid-reflux injury to the esophageal mucosa. Risk factors for BE include conditions that are associated with GER such as mental retardation, esophageal stricture, esophageal atresia, and reversed gastric tube esophagoplasty. Barrett's syndrome increases the risk of esophageal adenocarcinoma by 30 to 40 times.

METHODS

All children with the risk factors had repeated esophagoscopy and multiple mucosal biopsies before and after therapy.

RESULTS

Eleven children have been documented with BE. The initial diagnoses were: GER, 5; esophageal atresia, 4; nasogastric intubation, 1; lye ingestion, 1. A gastric tube esophagoplasty had been performed in three patients with BE in the esophagus proximal to the anastomosis. Three children with mid-esophageal strictures and long segments of BE had total resection with colic interposition. An additional two patients with tight stricture were treated with colic-patch esophagoplasty without resection. The final three patients were treated with fundoplication alone.

CONCLUSIONS

Barrett's esophagus can be caused by acid from gastric tubes but responds to H2 blockers and diet. Resection eliminates BE; esophagoplasty only controls the stricture and must be accompanied by fundoplication. Barrett's esophagus persists in patients with fundoplication alone if reflux control is incomplete. The authors conclude that acid reflux must be controlled to treat BE successfully or the involved segment must be resected. Esophagogastrostomy apparently predisposes to BE.

Scytophycins, novel microfilament-depolymerizing agents which circumvent P-glycoprotein-mediated multidrug resistance

Cells demonstrating the multidrug resistance phenotype because of overexpression of P-glycoprotein, a drug efflux pump, are resistant to the cytotoxic effects of most natural product drugs. To determine if P-glycoprotein confers resistance to the syctophycins, a family of natural cytotoxic macrolides recently isolated from cyanobacteria of the family Syctone-mataceae, we have characterized the effects of these compounds on drug-sensitive (SKOV3) and drug-resistant (SKVLB1) human ovarian carcinoma cells. While SKVLB1 cells demonstrated > 150- and 10,000-fold decreases in sensitivity to Adriamycin and vinblastine, respectively, they were equally sensitive as SKOV3 cells to the antiproliferative effects of tolytoxin and certain related scytophycins. The SKVKB1 cells were 4- to 11-fold resistant to other scytophycins and were 14-fold resistant to cytochalasin B. Microfilaments in SKOV3 and SKVLB1 cells were depolymerized by similar concentrations of tolytoxin, while cytochalasin B was less potent toward SKVLB1 cells than SKOV3 cells. Both tolytoxin and cytochalasin B enhanced the cytotoxicity of vinblastine toward SKVLB1 cells; however, neither compound affected the sensitivity to Adriamycin or cisplatin. Verapamil markedly increased the accumulation of [3H]vinblastine by SKLVB1 cells, while cytochalasin B caused only modest increase, and tolytoxin had no effect on [3H]vinblastine accumulation. These results suggest that some of the scytophycins, including tolytoxin, are not subject to P-glycoprotein-mediated efflux from cells exhibiting multidrug resistance due to overexpression of this transport protein. These compounds may therefore be useful for killing drug-resistant tumor cells.

31P magnetic resonance spectroscopy in Alzheimer's and Pick's disease

Previous studies have suggested a defect in phosphorus metabolism in Alzheimer's disease (AD) gray matter. We have studied phosphorus metabolites in both gray and white matter in autopsy specimens of nine subjects with late-stage AD, three with Pick's disease and seven age-matched controls. Phosphorus metabolites sugar phosphate (SU), phosphomonoester (PME), phosphodiester (PD), and inorganic phosphate (PI) were quantified as mole percentages in regional neocortical specimens using nuclear magnetic resonance spectroscopy. Senile plaque (SP) and neurofibrillary tangle (NFT) counts were determined in adjacent cortical sections. In the inferior parietal lobule gray and white matter, mole percentage normalized PME, and PD were significantly greater than control values in both AD and Pick's disease. A significant correlation was found between PD and NFT in AD parietal gray matter. Our data indicates that phosphorus metabolite alterations are present in two cortical degenerative diseases and are not likely to be specific for AD.

Action of tolytoxin on cell morphology, cytoskeletal organization, and actin polymerization

Tolytoxin, a cytostatic, antifungal macrolide produced by blue-green algae of the genus Scytonema, is a potent, reversible inhibitor of cytokinesis in cultured mammalian cells. Treatment of KB cells with 2-16 nM tolytoxin results in profound morphological changes, beginning with the formation of zeiotic processes and culminating in nuclear protrusion. In L1210 cells, cytokinesis is inhibited by as little as 2 nM tolytoxin, while karyokinesis proceeds normally, resulting in polynucleation. Tolytoxin specifically disrupts microfilament organization in A10 cells, while having no apparent effect on microtubules or intermediate filaments. Tolytoxin inhibited actin polymerization in vitro and also caused the depolymerization or fragmentation of F-actin in vitro. Tolytoxin exhibits effects that closely resemble those of cytochalasin B but is effective at concentrations 1/50-1/1,000 that of cytochalasin B.

Cariostatic and ultraconservative sealed restorations: six-year results

The objective of this clinical study was to determine the ability of an ultraconservative, sealed composite resin restoration, without a traditional cavity preparation and without the removal of the carious lesion, to arrest Class I caries. Tooth preparation was limited to placing a bevel in the enamel. These restorations were compared, over 6 years, with (1) ultraconservative, localized, sealed amalgam restorations with no extension for prevention and (2) traditional, unsealed amalgam restorations with the usual extension for prevention outline form. Caries was arrested by the ultraconservative, sealed composite resin restorations for 6 years. Complete sealant retention on the sealed amalgam restorations was somewhat lower than that on the sealed composite resin restorations; conversely, partial sealant retention was higher for the sealed amalgam group. The marginal integrity of the sealed amalgam restorations was significantly superior to that of the unsealed amalgam restorations. The sealant also protected Class I posterior composite resin restorations against wear.

The role of myoneural and luminal continuity in the coordination of canine gastroduodenal patterns of motility

Our aim was to determine the role of intrinsic myoneural and enteric luminal continuity in the coordination of gastric and duodenal motility patterns. Three groups of dogs were prepared: five dogs with an intact gastrointestinal tract served as a Control group; four dogs had transection and reanastomosis of the duodenum 0.5 cm distal to the pylorus (Pyloric Transection group); and seven dogs had identical proximal duodenal transection, but with oversewing of duodenum and pylorojejunostomy to a Roux-en-Y limb (Roux-en-Y group). In the Control and Pyloric Transection groups, the gastric and intestinal MMCs were similar in appearance, the cycle durations (x +/- SEM) were not different (134 +/- 19 vs 111 +/- 26 min, respectively; P > 0.05), and the times between the start of gastric and duodenal Phase III (gastroduodenal latency) were similar (6 +/- 1 vs 10 +/- 3 min; P > 0.05). In the Roux-en-Y group, MMCs also occurred in six of seven dogs but tended to have a longer cycle duration (176 +/- 19 min) and a more variable gastroduodenal latency (23 +/- 15 min). Plasma motilin concentration, measured only in the Roux-en-Y group, was greater during Phase III in the stomach and duodenum than during Phases I or II (P < 0.05). Feeding inhibited the gastric and duodenal MMCs in all groups, but the duodenal MMC returned earlier in the Roux-en-Y group. The Roux-en-Y jejunal limb exhibited a postprandial pattern in only seven of 14 studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of spinal cord repair kinetics on the practice of altered fractionation schedules

The kinetics of repair of sublethal lesions in the spinal cord was assessed in detail using a rodent model. Experiments were designed to obtain the fractionation sensitivity, alpha/beta, and to quantify the kinetics of repair after a clinically relevant fraction size. Pairs of 2-Gy fractions at intervals ranging from 0 to 24 h were given from Monday through Friday, to cumulative doses of 40-84 Gy. In addition, two groups of animals received 1.5 or 1.2 Gy twice a day at 8-h intervals, 5 days a week, to total doses of 66-90 Gy and 67.2-98.4 Gy, respectively. All irradiations were followed by a top-up dose of 16 Gy. Analysis of the experimental data revealed that a bi-exponential repair model fit the experimental data significantly better than did the mono-exponential model (p = 0.002). The repair half times obtained were 0.7 (0.2-1.3) h and 3.8 (2.6-4.9) h, respectively. The proportion of injury repaired by the longer half time was estimated to be 0.62 (0.37-0.86). The data showed that delivering 2 fractions per day at 6- or 8-h intervals instead of one per day led to a 16.5% (11.8-21.1%) and 13.5% (9.1-17.8%) reduction in the tolerance, respectively. Finally, the results indicated that when incomplete repair between fractions was accounted for, the linear-quadratic (LQ) model was valid in describing fractionation response down to 1.2 Gy per fraction.

Crystal structure of peroxynitrite-modified bovine Cu,Zn superoxide dismutase

The crystal structure of bovine Cu,Zn superoxide dismutase modified with peroxynitrite (ONOO-) was determined by X-ray diffraction, utilizing the existing three-dimensional model of the native structure deposited in the Brookhaven Protein Data Bank (J. A. Tainer et al., J. Mol. Biol. 160, 181-217, 1982). The native structure and the modified derivative were refined to R factors of 19.0 and 18.7% respectively using diffraction data from 6.0 to 2.5 A. The major result after reaction with peroxynitrite was the appearance of electron density 1.45 A from a single epsilon carbon of Tyr-108, the only tyrosine residue in the sequence. Tyr-108 is a solvent-exposed residue 18 A from the copper atom in the active site. The electron density was consistent with nitration of Tyr-108 at one of the epsilon carbons to form 3-nitrotyrosine. We propose that the nitration occurs in solution by transfer of a nitronium-like species from the active site on one superoxide dismutase dimer to the Tyr-108 of a second dimer.

Perinatal ovarian cyst: a nonsurgical approach

A case of an ovarian cyst diagnosed antenatally by ultrasound and showing spontaneous resolution within 5 months after birth is presented. On the basis of this case and others reported in the literature, we recommend expectant follow-up of such lesions with operation recommended only for cysts with solid or complex components or cysts causing symptoms from large size or torsion.

Pulmonary veno-occlusive disease and the CREST variant of scleroderma

Pulmonary veno-occlusive disease is a rare cause of pulmonary hypertension. The authors describe a 48-year-old female with the Calcinosis-Raynaud's phenomenon-Esophageal dysmotility-Sclerodactyly-Telangiectasia (CREST) variant of scleroderma who developed acute pulmonary hypertension with pulmonary infiltrates and a normal pulmonary capillary wedge pressure. At post mortem examination typical changes of pulmonary veno-occlusive disease were found. Similarities between this and other cases in the literature suggest a possible association between the CREST variant of scleroderma and pulmonary veno-occlusive disease.

Peroxynitrite-mediated tyrosine nitration catalyzed by superoxide dismutase

Peroxynitrite (ONOO-), the reaction product of superoxide (O2-) and nitric oxide (NO), may be a major cytotoxic agent produced during inflammation, sepsis, and ischemia/reperfusion. Bovine Cu,Zn superoxide dismutase reacted with peroxynitrite to form a stable yellow protein-bound adduct identified as nitrotyrosine. The uv-visible spectrum of the peroxynitrite-modified superoxide dismutase was highly pH dependent, exhibiting a peak at 438 nm at alkaline pH that shifts to 356 nm at acidic pH. An equivalent uv-visible spectrum was obtained by Cu,Zn superoxide dismutase treated with tetranitromethane. The Raman spectrum of authentic nitrotyrosine was contained in the spectrum of peroxynitrite-modified Cu,Zn superoxide dismutase. The reaction was specific for peroxynitrite because no significant amounts of nitrotyrosine were formed with nitric oxide (NO), nitrogen dioxide (NO2), nitrite (NO2-), or nitrate (NO3-). Removal of the copper from the Cu,Zn superoxide dismutase prevented formation of nitrotyrosine by peroxynitrite. The mechanism appears to involve peroxynitrite initially reacting with the active site copper to form an intermediate with the reactivity of nitronium ion (NO2+), which then nitrates tyrosine on a second molecule of superoxide dismutase. In the absence of exogenous phenolics, the rate of nitration of tyrosine followed second-order kinetics with respect to Cu,Zn superoxide dismutase concentration, proceeding at a rate of 1.0 +/- 0.1 M-1.s-1. Peroxynitrite-mediated nitration of tyrosine was also observed with the Mn and Fe superoxide dismutases as well as other copper-containing proteins.

Effect of zinc binding on the structure and stability of fibrolase, a fibrinolytic protein from snake venom

Fibrolase is a metalloprotease with potential use as a fibrinolytic agent. Loss of the intrinsic zinc atom leads to a rapid decrease in enzymatic activity. Circular dichroism measurements indicate that there is a partial unfolding of an alpha-helical section of the protein concomitant with the loss of zinc. Removal of zinc can be affected by elevated temperatures, acidic pH values, and addition of chelating agents. At low molar concentrations, both ethylenediaminetetraacetic acid (EDTA) and dithiothreitol (DTT) were found to remove zinc efficiently. Analysis of the sequence of fibrolase identified a segment which possessed a high degree of homology with the metal binding site of other zinc proteases, such as thermolysin and the collagenases. However, the putative zinc binding site in fibrolase lacks the additional glutamate ligand found in thermolysin and subtilisin. This sequence is also predicted to adopt an alpha-helical conformation. Together, these data indicate that there is a well-defined metal binding site in fibrolase and that metal binding is the most important factor governing the stability of this protein.

Completion pancreatectomy following pancreaticoduodenectomy: clinical experience

While pancreaticoduodenectomy is today performed with an operative mortality of less than 5%, the incidence of significant operative morbidity remains at least 25%. Albeit rarely, completion pancreatectomy during the early postoperative period may be required to manage uncontrolled pancreatic anastomotic leaks. From 1964 to 1988, pancreaticoduodenectomy was performed on 479 patients at our institution, 178 (37%) of whom required re-operation in the early postoperative period. Of these, 11 (6%) patients underwent completion pancreatectomy at a mean interval of 18 days following Whipple resection. The indications prompting re-operation included a suspected pancreatic leak (n = 8), intraabdominal hemorrhage (n = 2), and pancreaticocutaneous fistula (n = 1). Operative findings necessitating completion pancreatectomy included pancreatic anastomotic dehiscence with severe surrounding inflammation/necrosis prohibiting reanastomosis or repair (n = 10) and necrotizing pancreatitis with uncontrolled hemorrhage (1). Seven (64%) of these 11 patients died postoperatively of sepsis and multiple organ failure. The mean hospital stay in the 4 surviving patients was 46 days (range, 26 to 53 days). These 4 patients survived for a mean period of 24 months following hospital dismissal.

Nissen fundoplication in children with profound neurologic disability. High risks and unmet goals

Anti-reflux procedures have been advocated in children with profound neurologic disability referred for feeding gastrostomy when gastroesophageal reflux is present. Facilitation of care, reduction in pneumonia and vomiting, and improvement in the general health and survival of these children have been major goals of fundoplication and gastrostomy. In large pediatric series, these procedures have been reported to have low risk and negligible mortality rates. Recent reports, however, document an increased incidence of sequelae of fundoplication in children with profound neurologic disability. This paper retrospectively reviews a series of 35 nonverbal, nonambulatory pediatric patients undergoing a total of 39 fundoplications (37 Nissen, 1 Thal, and 1 Belsey) over an 11-year period. Neurologic impairment of 17 (49%) patients was acquired, 13 (37%) congenital, and 5 (14%) due to a syndrome. Perioperative complications occurred in six (17%). Three additional complications led to early postoperative death. A fourth early death was unexplained. Fourteen (40%) had recurrent pneumonia, 11 (31%) recurrent vomiting, 8 (23%) choking-gagging-retching complex, and 3 (9%) bowel obstruction requiring laparotomy. Recurrent gastroesophageal reflux was documented in seven (20%) patients. A second ARP was performed in six (17%). There were 14 (40%) late deaths. Although the major goals of anti-reflux procedure are clearly achieved in many severely impaired children with gastroesophageal reflux, the use of Nissen fundoplication to resolve the complications of swallowing disorders and improve outcome with an acceptably low risk in this complex set of patients does not appear to be established.

Liver transplantation: living-related donations

The LRLT procedure appears to be a promising alternative and adjunct to conventional liver transplantation. The advantages to this technique are a donor for each recipient, an improved quality of graft, and a reduction in pretransplant mortality in children. The procedure is not without risks, but the overall benefits seem to outweigh these risks, and only future experience will tell otherwise. Will there continue to be a need for such a procedure? We believe there will be, because the number of candidates needing transplantation will continue to grow and the demand for cadaveric organs will never be met. However, the procedure is extremely labor and resource intensive, and it is our belief that only a handful of large major medical centers will be able to adopt a live-donor program.

Successful pregnancy in a patient with a single ventricle

Single ventricle is an uncommon form of congenital heart disease. We report a successful pregnancy and delivery in a mother with surgically confirmed single ventricle.

Expression of the cardiac Na(+)-Ca2+ exchanger in insect cells using a baculovirus vector

We constructed a recombinant baculovirus containing cardiac Na(+)-Ca2+ exchanger cDNA under control of the polyhedrin promoter. When either Sf9 or Sf21 insect cells are infected with the recombinant baculovirus, both Na(+)-Ca2+ exchanger protein and Na(+)-Ca2+ exchange activity are expressed at high level. The exchanger protein can be detected either by immunoblot or by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole cell lysate. At maximal expression, the exchanger protein comprises about 3-5% of total cell protein. The Na(+)-Ca2+ exchanger can be purified by alkaline extraction of infected cells followed by elution from a Bio-Rad Prep Cell. The expressed exchanger, in contrast to the native sarcolemmal exchanger, is not glycosylated. Sf9 cells expressing the exchanger are intensely stained by anti-exchanger antibodies as observed by immunofluorescence. The expressed exchanger is predominantly in the cell plasma membrane since it is susceptible to extracellular trypsin. In 45Ca2+ flux experiments, the expressed Na(+)-Ca2+ exchange activity is about 4-fold higher than that in cultured neonatal rat heart cells. The expressed exchanger was also analyzed electrophysiologically using whole cell patch clamp techniques. The characteristics of inward exchange currents in infected Sf21 cells are very similar to those of ventricular myocytes, although of a larger magnitude.

Cyclic interdigestive pancreatic exocrine secretion: is it mediated by neural or hormonal mechanisms?

Cyclic interdigestive exocrine pancreatic secretion and duodenal motility are closely linked. However, the mechanisms controlling this association are not well understood. The aim of this study was to determine whether a neural or hormonal mechanism controls the temporal association of interdigestive secretion and duodenal motility. In five dogs, the pancreas was autotransplanted to the pelvis with anastomosis of the pancreatic duct orifice to the bladder. Electrodes were positioned to monitor motility patterns of the in situ duodenum. After 10 days, dogs were studied on four occasions during fasting. Pancreatic output of amylase activity continued to cycle, but the periodicity of enzyme peaks (mean +/- SE) was different from the period of the duodenal migrating motor complex (MMC) (60 +/- 3 vs. 125 +/- 7 minutes; P less than 0.05). When grouped according to phase of duodenal MMC, amylase output per 10 minutes during phase I was significantly less than the outputs during phase II or III (135 +/- 52, 214 +/- 78, and 228 +/- 73 x 10(3) U; P less than 0.05). However, there was no temporal relationship of the cyclic output of amylase to duodenal phase III. No differences were found when amylase output was analyzed for the 30 minutes before phase III compared with the 30 minutes after phase III (687 +/- 253 vs. 378 +/- 110 x 10(3) U; P greater than 0.05). Plasma motilin concentrations varied with duodenal MMC, but no relationship existed between plasma motilin or plasma pancreatic polypeptide and peaks in amylase output. This study suggests that the close temporal coordination of interdigestive pancreatic exocrine secretion and duodenal motility is controlled primarily by a neural mechanism.

A primate model for human cerebral malaria: Plasmodium coatneyi-infected rhesus monkeys

A major factor in the pathogenesis of human cerebral malaria is blockage of cerebral microvessels by the sequestration of parasitized human red blood cells (PRBC). In vitro studies indicate that sequestration of PRBC in the microvessels is mediated by the attachment of knobs on PRBC to receptors on the endothelial cell surface such as CD36, thrombospondin (TSP), and intercellular adhesion molecule-1 (ICAM-1). However, it is difficult to test this theory in vivo because fresh human brain tissues from cerebral malarial autopsy cases are not easy to obtain. Although several animal models for human cerebral malaria have been proposed, none have shown pathologic findings that are similar to those seen in humans. In order to develop an animal model for human cerebral malaria, we studied brains of rhesus monkeys infected with the primate malaria parasite, Plasmodium coatneyi. Our study demonstrated PRBC sequestration and cytoadherence of knobs on PRBC to endothelial cells in the cerebral microvessels of these monkeys. Cerebral microvessels with sequestered PRBC were shown by immunohistochemical analysis to possess CD36, TSP, and ICAM-1. These proteins were not evident in the cerebral microvessels of uninfected control monkeys. Thus, our study indicates, for the first time, that rhesus monkeys infected with P. coatneyi can be used as a primate model to study human cerebral malaria. By using this animal model, we may be able to evaluate strategies for the development of vaccines to prevent human cerebral malaria.

The protein kinase inhibitor, staurosporine, does not inhibit phosphoinositide kinases

The effects of the protein kinase inhibitor staurosporine on phosphatidylinositol (PI) kinase and phosphatidylinositol 4-phosphate (PIP) kinase activities in brain membranes, and the synthesis of polyphosphoinositides in cultured NIH 3T3 fibroblasts were examined. Staurosporine, at concentrations up to 1 microM did not significantly modulate either PI kinase or PIP kinase activity in brain membranes. DNA synthesis was dose-dependently inhibited by sub-nanomolar concentrations of staurosporine; however, cells treated with up to 1 microM staurosporine contained levels of PIP and phosphatidylinositol 4,5-bisphosphate (PIP2) similar to those observed in untreated cells. Therefore, phosphoinositide kinases do not appear to be either directly or indirectly affected by staurosporine.

Baculovirus-mediated expression of the Na+/glucose cotransporter in Sf9 cells

We have used baculovirus (AcNPV) to express the Na+/glucose cotransporter protein in cultured Sf9 cells. We constructed a baculovirus transfer vector containing the cDNA for the rabbit intestinal Na+/glucose cotransporter (SGLT1) under the control of the polyhedrin gene promoter. Recombinant baculovirus was obtained by cotransfection of SF9 cells with wild-type AcNPV DNA and the transfer vector. Recombinant virus was identified by Southern blotting and then purified. Recombinant infected Sf9 cells expressed a protein which was recognized by anti-peptide antibodies raised to sequences of the cloned Na+/glucose cotransporter. This protein migrated with a molecular mass of 55 kD by SDS-PAGE, similar to the in vitro translation product of SGLT1. An identical protein was metabolically labeled with [35S]methionine. Cells which synthesized the transport protein showed Na(+)-dependent alpha MeGlc transport. Micromolar phlorizin inhibited transport. Uninfected and wild-type virus infected Sf9 cells did not have Na(+)-dependent glucose transport. All transport protein migrated at 45% sucrose (w/w) by density gradient sedimentation, suggesting that the expressed transporter is membrane associated. We conclude that we have functionally expressed the rabbit intestinal Na+/glucose cotransporter in Sf9 cells. The transporter is not heavily glycosylated, and this is consistent with previous work showing that glycosylation is not necessary for function. We are poised to purify and characterize this protein from a structure-function perspective.

Sealed restorations: 5-year results

This clinical study determined the feasibility of a sealed resin composite restoration to arrest dental caries using a minimal tooth preparation: a bevel in enamel only without removal of the carious lesion. These ultra-conservative sealed composite restorations placed over caries (CompS/C) were compared with ultra-conservative sealed amalgam restorations (AGS) that had no "extension for prevention". The CompS/C restorations were also compared with the traditional (unsealed) amalgam restorations (AGU) with the "extension for prevention" outline form. Caries progress, as determined by standardized radiographs, revealed that after 5 years caries remained arrested under the CompS/C restorations; the marginal integrity was similar for the CompS/C and the AGS groups, and exhibited highly significant superiority to the AGU restorations (Chi square, P less than = 0.00004). Complete sealant retention over the amalgam restorations (AGS group) was less than over the composite restorations (CompS/C), and conversely, partial sealant retention was higher for the AGS group. Sealants also appeared to protect the posterior composite restorations against wear.

Inhibition of phosphatidylinositol 4-phosphate kinase by heparin. A possible mechanism for the antiproliferative effects of heparin

Heparin and related glycosaminoglycans are important modulators of vascular smooth muscle cell growth, and may be involved in pathological processes such as atherosclerosis. Since polyphosphoinositide metabolism is a major mechanism for regulating cellular activities, including proliferation, the effects of glycosaminoglycans and polyanionic compounds on the activities of phosphoinositide kinases were characterized. Heparin and heparan sulphate caused dose-dependent inhibitions of rat brain cytosolic phosphatidylinositol 4-phosphate (PIP) kinase activity, with half-maximal inhibitory concentrations of approx. 0.5 and 5 microM respectively. PIP kinase was also inhibited by several dextran sulphates, but was not sensitive to inhibition by keratin sulphate, chondroitin sulphate or hyaluronic acid. Polynucleotides and acidic polypeptides were only weakly inhibitory. Heparin did not alter either the PIP- or the Mg(2+)-dependence of PIP kinase. Addition of heparin to brain membranes suppressed PIP kinase activity without affecting phosphatidylinositol (PI) kinase activity. Heparin interfered with the ability of a GTP analogue to stimulate PIP kinase activity in these membranes, suggesting that it uncouples the kinase from an activating guanine-nucleotide-binding protein. In cultured A-10 vascular smooth muscle cells, heparin caused dose- and time-dependent inhibition of [3H]thymidine incorporation into DNA. Similar treatments with heparin decreased cellular levels of phosphatidylinositol 4,5-bisphosphate (PIP2) without changing PI and PIP levels. Therefore heparin-mediated inhibition of PIP kinase appears to lead to decreases in PIP2 levels which may attenuate cellular proliferation.

Ultraconservative sealed restorations: three-year results

The overall objective of this clinical study was to determine the feasibility of using a sealed composite restoration to arrest caries without the removal of the carious lesion and without the traditional cavity preparation. The minimal tooth preparation (a bevel in enamel) usually did not require any anesthetic injection and conserved tooth structure. These ultraconservative sealed composite restorations placed over caries (CompS/C) have been compared with ultraconservative sealed amalgam restorations (AGS) and with the traditional outline form (unsealed) amalgam restorations (AGU). This clinical study has shown that: (1) caries can be arrested by the CompS/C restoration for a period of three years; (2) the marginal integrity of the AGS restorations showed a definite trend toward improvement as compared to the AGU restorations; and (3) complete sealant retention over posterior restorations was similar in both the CompS/C and the AGS groups during the first two years; however, at Year 3 complete sealant retention was 16 percent higher in the CompS/C than in the AGS group.